JP6209466B2 - Flow measuring device and flow control valve - Google Patents

Description

  The present invention relates to a flow rate measuring device that measures the flow rate of a fluid that is controlled by adjusting the opening of a valve body, and a flow rate control valve that incorporates the flow rate measuring device.

  Conventionally, both a flow meter and a control valve are arranged in the pipe line, and the opening degree of the control valve is controlled based on the flow rate measured by the flow meter. However, such a method requires a flow meter separately from the control valve. In addition, many flow meters such as an orifice type flow meter and a hot wire type flow meter require a straight pipe part in front of the flow meter for stable measurement, which requires cost and space.

  Therefore, a flow control valve having both a flow measurement function and a valve opening control function is desired and put into practical use (see, for example, Patent Document 1). The flow rate control valve includes a valve body having a pipe line that forms a fluid flow path and a valve body that regulates the flow rate of the fluid flowing in the pipe line, and an opening degree of the valve body that is attached to the valve body. And an actuator to be controlled. The valve body includes a first pressure sensor that detects a pressure P1 upstream of the valve body, a second pressure sensor that detects a pressure P2 downstream of the valve body, and an opening degree of the valve body (valve opening degree). ) A valve opening sensor for detecting θ is provided. A CPU and memory are mounted on the actuator.

  In this flow control valve, a characteristic table in the memory includes a reference characteristic table indicating a relationship between the valve opening degree θ and the flow coefficient Cv at a predetermined reference differential pressure (differential pressure between the upstream and downstream of the valve body). A characteristic table at the time of low differential pressure showing the relationship between the valve opening degree θ and the flow coefficient Cv at a differential pressure lower than the reference differential pressure, and a predetermined low opening of the valve body at a differential pressure higher than the reference differential pressure A characteristic table at the time of high differential pressure and low opening indicating the relationship between the valve opening θ below the degree threshold and the flow coefficient Cv is stored.

  In this flow control valve, the CPU obtains a differential pressure ΔP between the upstream and downstream of the valve body from the pressure P1 from the first pressure sensor and the pressure P2 from the second pressure sensor, and the current differential pressure ΔP is the reference. When the pressure is lower than the differential pressure, the flow coefficient Cv corresponding to the differential pressure ΔP and the current valve opening θ is obtained from the characteristic table at the time of low differential pressure, and based on the obtained flow coefficient Cv and the current differential pressure ΔP. When the flow rate Q of the fluid flowing in the pipe is calculated and the current differential pressure ΔP is higher than the reference differential pressure and the current valve opening θ is equal to or lower than the low opening threshold, the differential pressure ΔP and the current The flow coefficient Cv corresponding to the valve opening θ is obtained from the characteristic table at the time of high differential pressure and low opening, and the flow quantity Q of the fluid flowing in the pipeline is calculated based on the obtained flow coefficient Cv and the current differential pressure ΔP. To do. Then, the calculated flow rate Q is compared with the set flow rate Qsp as the measured flow rate Qpv, and the valve opening degree θ is controlled so that the measured flow rate Qpv matches the set flow rate Qsp.

Japanese Patent No. 5113722 Japanese Patent Publication No. 3-38605 JP 2013-181877 A

  However, in the flow control valve disclosed in Patent Document 1, the flow coefficient Cv when the valve opening θ and the differential pressure ΔP change is obtained from the characteristic table at the time of low differential pressure or the characteristic table at the time of high differential pressure and low opening. This can improve the reliability of the measured flow rate, but if the fluid flowing in the pipe is a liquid (incompressible fluid), if the temperature of the liquid changes greatly, the kinematic viscosity coefficient (kinematic viscosity) of the liquid Since the difference between the calculated flow rate and the actual flow rate increases, it becomes difficult to accurately measure the flow rate.

  Patent Document 2 discloses a digital valve control device that detects a fluid temperature and corrects a control flow rate. In this digital valve control device, the modified Reynolds number Rm = k · v · A / ν (k: variable that changes with valve displacement, v: fluid flow velocity, ν: kinematic viscosity, A: valve opening area) and flow coefficient The relationship with Cv is the same regardless of the valve opening.

  However, in reality, the change in the flow aspect with respect to the change in the Reynolds number is not necessarily the same regardless of the valve opening. For this reason, if there is a portion where the relationship between the corrected Reynolds number Rm and the flow coefficient Cv is different from the relationship defined in the table, that portion becomes an error in flow measurement.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a flow rate measuring device capable of measuring the flow rate of a fluid (liquid) with high accuracy. . Another object of the present invention is to provide a flow rate control valve incorporating a flow rate measuring device capable of measuring the flow rate of a fluid (liquid) with high accuracy.

  In order to achieve such an object, the present invention is directed to a flow measuring device that measures the flow rate of a fluid controlled by adjusting the opening degree of a valve body using a fluid to be measured as a liquid. A flow coefficient table storage unit that stores a flow coefficient table indicating the relationship between the flow coefficient, a flow coefficient acquisition unit that acquires a flow coefficient according to the current opening of the valve body from the flow coefficient table as a current flow coefficient, and a valve body A flow rate calculation unit that obtains the flow rate of the fluid as a temporary flow rate from the current differential pressure between the upstream and downstream and the current flow rate coefficient obtained from the flow rate coefficient table, and a dynamic that indicates the relationship between the fluid temperature and the fluid kinematic viscosity. A kinematic viscosity table storage unit that stores a viscosity table, and a flow rate correction table that indicates a relationship between a flow rate correction coefficient created for each opening of the valve body and a flow rate correction coefficient determination value corresponding to the flow rate correction coefficient Correction Te Obtained from the dynamic storage table, the kinematic viscosity acquisition unit that acquires the kinematic viscosity according to the current temperature of the fluid from the kinematic viscosity table as the current kinematic viscosity, and the current differential pressure between the upstream and downstream of the valve body and the kinematic viscosity table The flow rate correction coefficient determination value calculation unit for obtaining the current flow rate correction coefficient determination value from the information including the current kinematic viscosity, and the current opening degree of the valve body and the flow rate correction coefficient determination calculation unit from the flow rate correction table. The flow rate correction coefficient acquisition unit that acquires the flow rate correction coefficient according to the determined value of the current flow rate correction coefficient, and the flow rate correction coefficient acquired by the flow rate correction coefficient acquisition unit as the temporary flow rate obtained by the flow rate calculation unit. And a flow rate correction unit that corrects the flow rate by multiplying the flow rate to a corrected flow rate (Claim 1).

According to this invention, the flow coefficient Cv corresponding to the current opening degree θ of the valve body is acquired from the flow coefficient table as the current flow coefficient, and from the current differential pressure ΔP between the upstream and downstream of the valve body and the flow coefficient table. The temporary flow rate Q ′ of the fluid is obtained from the acquired current flow coefficient Cv. The kinematic viscosity ν corresponding to the current temperature T of the fluid is acquired from the kinematic viscosity table as the current kinematic viscosity, and the current kinematic viscosity acquired from the current differential pressure between the upstream and downstream of the valve body and the kinematic viscosity table. DOO current flow rate correction coefficient determination value obtained from information including the flow rate correction factor F _R corresponding to the current flow rate correction coefficient determination value, which is the current opening degree θ and obtains the valve body is obtained from the flow rate correction table The Then, the provisional flow rate Q ′ is corrected by the flow rate correction coefficient F _R acquired from the flow rate correction table to obtain a corrected flow rate Q (Q = F _R · Q ′).

  In the present invention, a density ratio table storage unit for storing a density ratio table indicating the relationship between the temperature of the fluid and the density ratio of the fluid, and the density ratio corresponding to the current temperature of the fluid from the density ratio table A density ratio acquisition unit that acquires the ratio, and in the flow rate calculation unit, the current differential pressure between the upstream and downstream of the valve body, the current flow coefficient acquired from the flow coefficient table, and the density ratio table The flow rate of the fluid is obtained as a temporary flow rate from the current density ratio, and in the flow rate correction coefficient determination value calculation unit, the current differential pressure between the upstream and downstream of the valve body and the current density ratio obtained from the density ratio table And the current flow rate correction coefficient determination value may be obtained from information including the current kinematic viscosity obtained from the kinematic viscosity table (claim 2).

In the invention according to claim 2, the flow coefficient Cv corresponding to the current opening degree θ of the valve body is acquired from the flow coefficient table as the current flow coefficient, and the density ratio ρ ₁ / ρ corresponding to the current temperature T of the fluid. ₀ (ρ ₁ : fluid density at fluid temperature, ρ ₀ : fluid density at reference temperature) is acquired from the density ratio table as the current density ratio, and the current differential pressure ΔP and the flow coefficient between the upstream and downstream of the valve body The temporary flow rate Q ′ of the fluid is obtained from the current flow coefficient Cv acquired from the table and the current density ratio ρ ₁ / ρ ₀ acquired from the density ratio table. In addition, the kinematic viscosity ν corresponding to the current temperature T of the fluid is acquired from the kinematic viscosity table as the current kinematic viscosity, and the current differential pressure between the upstream and downstream of the valve body and the current density acquired from the density ratio table. The current flow rate correction coefficient determination value is obtained from the information including the ratio and the current kinematic viscosity obtained from the kinematic viscosity table, and the current opening degree θ of the valve body and the determined current flow rate correction coefficient determination value are obtained. depending flow rate correction factor F _R is obtained from the flow rate correction table. Then, the provisional flow rate Q ′ is corrected by the flow rate correction coefficient F _R acquired from the flow rate correction table to obtain a corrected flow rate Q (Q = F _R · Q ′).

As an embodiment of the present invention, for example, a flow rate correction table having a flow rate correction coefficient determination value f as a ratio Q ′ / ν between the temporary fluid flow rate Q ′ and the kinematic viscosity ν of the fluid is stored. A ratio Q ′ / ν between the obtained temporary flow rate Q ′ and the current kinematic viscosity ν obtained from the kinematic viscosity table is obtained as a current flow rate correction coefficient determination value f, and the current opening θ of the valve body and the obtained current value the flow rate correction coefficient determination value f = Q '/ ν flow correction factor F _R corresponding to be acquired from the flow rate correction table. Then, the temporary flow rate Q ′ obtained by the flow rate calculation unit is corrected by the flow rate correction coefficient F _R acquired from the flow rate correction table to obtain a corrected flow rate Q (Q = F _R · Q ′).

In the present invention, when the temporary flow rate Q ′ is obtained by the following equation (1) (Claim 3), the temporary flow rate Q ′ is information including the current differential pressure ΔP, and the current flow rate correction coefficient determination value. It can be said that f = Q ′ / ν is obtained from information including the current differential pressure ΔP and the current kinematic viscosity ν.
Q ′ = N · Cv · (ΔP) ^1/2 ... (1)
However, ΔP is a differential pressure between the upstream and downstream of the valve body, Cv is a flow coefficient, and N is a numerical constant.

In the present invention, when the temporary flow rate Q ′ is obtained by the following equation (2) (Claim 4), the temporary flow rate Q ′ includes the current differential pressure ΔP and the current density ratio ρ ₁ / ρ _0. The current flow rate correction coefficient determination value f = Q ′ / ν is obtained from information including the current differential pressure ΔP, the current density ratio ρ ₁ / ρ _0, and the current kinematic viscosity ν. .
Q ′ = N · Cv · (ΔP / (ρ ₁ / ρ ₀ )) ^1/2 ... (2)
Where ΔP is the differential pressure between the upstream and downstream of the valve body, Cv is the flow coefficient, ρ ₁ / ρ ₀ is the fluid density ratio (ρ ₁ : fluid density at fluid temperature, ρ ₀ : fluid density at reference temperature ), N is a numerical constant.

In the present invention, when the flow rate correction coefficient determination value f is Q ′ / ν, the corrected flow rate Q may be output as it is as the measured flow rate. flow rate correction coefficient determination value f = Q in viscosity ratio calculating section 'calculation of / [nu, acquisition of the flow rate correction factor F _R in the flow correction coefficient acquisition unit, the temporary flow rate Q obtained by the flow rate calculation unit in the flow correction unit' correction for May be repeated as a brush-up process (claim 8). In this case, for example, the brush-up process is repeated until the number of corrections of the temporary flow rate Q ′ in the flow rate correction unit reaches a predetermined number (Claim 9), or the previous correction flow rate Q (Q _BF ) in the flow rate correction unit. And a method of repeating the brush-up process until the difference between the current flow rate and the current correction flow rate (Q _AF ) is equal to or less than a predetermined value (claim 10).

Further, in the present invention, a flow rate correction table in which a value f expressed by the following equation (3) is used as a flow rate correction coefficient determination value is stored, and the current differential pressure ΔP between the upstream and downstream of the valve body, and kinematic viscosity From the current kinematic viscosity ν obtained from the table, a current flow correction coefficient determination value is obtained as a value f represented by the following equation (3), and the current opening θ of the valve body and the obtained current flow correction the flow rate correction factor F _R in accordance with the coefficient determination value f = (ΔP) ^1/2 / ν be acquired from the flow rate correction table, and the temporary flow rate Q 'obtained by the flow rate calculation unit acquires from the flow correction table rate A correction flow rate Q (Q = F _R · Q ′) may be corrected by the correction coefficient F _R (Claim 5).
f = (ΔP) ^1/2 / ν (3)
Where ΔP is the differential pressure between the upstream and downstream of the valve body, and ν is the kinematic viscosity of the fluid.

In the present invention, a flow rate correction table having a value f expressed by the following equation (4) as a flow rate correction coefficient determination value is stored, and the current differential pressure ΔP between the upstream and downstream of the valve body and the density ratio From the current density ratio ρ ₁ / ρ ₀ obtained from the table and the current kinematic viscosity ν obtained from the kinematic viscosity table, the current flow rate correction coefficient determination value as a value f expressed by the following equation (4): The flow rate correction coefficient F according to the current opening degree θ of the valve body and the determined current flow rate correction coefficient determined value f = (ΔP) ^1/2 / (ν (ρ ₁ / ρ ₀ ) ^1/2 ) _R is obtained from the flow rate correction table, and the provisional flow rate Q ′ obtained by the flow rate calculation unit is corrected by the flow rate correction coefficient F _R obtained from the flow rate correction table to obtain a corrected flow rate Q (Q = F _R · Q ′). (Claim 6).
f = (ΔP) ^1/2 / (ν (ρ ₁ / ρ ₀ ) ^1/2 ) (4)
Where ΔP is the differential pressure between the upstream and downstream of the valve body, ν is the kinematic viscosity of the fluid, ρ ₁ / ρ ₀ is the fluid density ratio (ρ ₁ : fluid density at fluid temperature, ρ ₀ : fluid at reference temperature Density).

  The flow rate measuring device of the present invention may be built in the flow rate control valve or connected to the flow rate control valve. The invention according to claim 11 of the present application is such that the flow rate measuring device according to claims 1 to 10 is incorporated in a flow control valve.

According to the present invention, the flow coefficient according to the current opening degree of the valve body is obtained from the flow coefficient table as the current flow coefficient, and obtained from the current differential pressure between the upstream and downstream of the valve body and the flow coefficient table. The flow rate of the fluid is obtained as a temporary flow rate from the current flow coefficient, the kinematic viscosity corresponding to the current temperature of the fluid is obtained from the kinematic viscosity table as the current kinematic viscosity, and the current differential pressure between the upstream and downstream of the valve body The current flow rate correction coefficient determination value is obtained from information including the current kinematic viscosity obtained from the kinematic viscosity table, and the flow rate correction according to the current opening of the valve body and the determined current flow rate correction coefficient determination value The coefficient is obtained from the flow rate correction table, and the provisional flow rate obtained from the current differential pressure between the upstream and downstream of the valve body and the current flow rate coefficient is multiplied by the obtained flow rate correction coefficient to obtain the corrected flow rate. Use the kinematic viscosity according to the current temperature of the Using the current opening degree and the current flow rate correction coefficient determined value (Q '/ [nu and ([Delta] P) such as ^1/2 / [nu) flow correction coefficient obtained from the valve body, a fluid (liquid) with high precision The flow rate can be measured.

It is a figure which shows the outline of one Embodiment of the flow control valve which incorporated the flow measuring device which concerns on this invention. It is a figure which illustrates the flow coefficient table (Cv table), kinematic viscosity table, and flow correction table which are used with this flow control valve. Is a diagram illustrating a flow rate correction curve representing a relationship between the flow rate correction coefficient determination value f = Q '/ ν and the flow correction factor (Reynolds number factor) F _R at a certain angle theta. It is a flowchart which shows an example (Embodiment 1) of the processing operation which CPU in the actuator of this flow control valve performs. FIG. 3 is a functional block diagram of a flow rate measurement unit according to Embodiment 1 that is realized as a processing operation of a CPU. It is a figure which illustrates the flow coefficient table (Cv table), density ratio table, kinematic viscosity table, and flow volume correction table which are used in Embodiment 2. 12 is a flowchart illustrating another example (second embodiment) of a processing operation executed by a CPU. It is a functional block diagram of the flow measurement part in Embodiment 2 implement | achieved as a processing operation of CPU. Flow rate correction factor F _R is a diagram showing a state go about close to an appropriate value. It is a figure which shows a mode that the measurement flow volume Qpv approaches a true value. 12 is a flowchart of another example of processing operations executed by the CPU (first example of the third embodiment). 10 is a flowchart of another example of processing operations executed by the CPU (second example of the third embodiment). It is a functional block diagram of the flow measurement part in Embodiment 3 implement | achieved as a processing operation of CPU. 10 is a flowchart of another example of processing operations executed by the CPU (first example of the fourth embodiment). 12 is a flowchart of another example of processing operations executed by the CPU (second example of the fourth embodiment). It is a functional block diagram of the flow measurement part in Embodiment 4 implement | achieved as a processing operation of CPU. 18 is a flowchart of another example (Embodiment 5) of the processing operation executed by the CPU. FIG. 10 is a diagram illustrating a flow rate correction table used in the fifth embodiment. It is a functional block diagram of the flow measurement part in Embodiment 5 implement | achieved as a processing operation of CPU. 18 is a flowchart of another example (sixth embodiment) of the processing operation executed by the CPU. It is a functional block diagram of the flow measurement part in Embodiment 6 implement | achieved as a processing operation of CPU. FIG. 10 is a diagram illustrating a flow rate correction table used in the sixth embodiment. It is a figure which shows the outline of one Embodiment (Embodiment 7) of the system which connected the flow measuring device which concerns on this invention to the flow control valve. It is a flowchart which shows the processing operation which CPU in this flow measuring device performs. 18 is a flowchart in the case where the same processing as in the second embodiment is performed in the seventh embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the fluid to be measured is a liquid, and the term “fluid” means all liquids.

[Embodiment 1]
FIG. 1 is a diagram showing an outline of an embodiment of a flow control valve incorporating a flow measuring device according to the present invention. In the figure, reference numeral 100 denotes a flow control valve, which includes a valve body 1 and an actuator 2 attached to the valve body 1.

  The valve body 1 includes a pipe line 1-1 that forms a fluid flow path, and a valve body 1-2 that regulates the flow rate of the fluid flowing through the pipe line 1-1. On the other hand, a differential pressure sensor S1 for detecting a differential pressure ΔP between the upstream and downstream sides is provided. Further, a temperature sensor S2 for detecting the temperature T of the fluid flowing in the pipe 1-1 is provided on the upstream side of the valve body 1-2.

  The actuator 2 includes a CPU 2-1, a memory 2-2, a display unit 2-3, and a motor 2-4, and the drive shaft of the motor 2-4 is connected to the valve element 1-2. . An opening degree sensor S3 for detecting the opening degree θ of the valve body 1-2 is provided at a connecting portion between the drive shaft of the motor 2-4 and the valve body 1-2.

  The CPU 2-1 of the actuator 2 has a differential pressure ΔP between the upstream and downstream of the valve body 1-2 detected by the differential pressure sensor S1, a temperature T of the fluid flowing in the pipe line 1-1 detected by the temperature sensor S2, and an opening. The opening degree θ of the valve body 1-2 detected by the degree sensor S3 and the set flow rate Qsp from the host device are given.

The memory 2-2 of the actuator 2 includes a flow coefficient table (Cv table) TB1 (see FIG. 2A) indicating the relationship between the opening degree θ of the valve body 1-2 and the flow coefficient Cv, and a fluid temperature T. And a kinematic viscosity table TB3 (see FIG. 2B) showing the relationship between the kinematic viscosity ν of the fluid and the fluid temporary flow rate Q ′ (described later) created for each opening degree of the valve body 1-2 and the fluid and the ratio of the kinematic viscosity ν Q '/ ν (flow correction coefficient determination value f) and the flow correction coefficient flow rate correction table TB4 showing the relationship between (Reynolds number factor) F _R (see FIG. 2 (c)) is stored ing. 3 illustrates a flow rate correction curve representing the relationship between the flow rate correction coefficient determination value f = Q ′ / ν and the flow rate correction coefficient (Reynolds number coefficient) F _R at the opening degree θ in FIG.

  Hereinafter, with reference to the flowchart shown in FIG. 4, processing operations unique to the present embodiment (Embodiment 1) executed by the CPU 2-1 of the actuator 2 according to the program stored in the memory 2-2 will be described.

  The CPU 2-1 reads the opening degree θ (current opening degree θ) of the valve element 1-2 from the opening degree sensor S3 (step S101). Further, the differential pressure ΔP (current differential pressure ΔP) between the upstream and downstream of the valve body 1-2 from the differential pressure sensor S1 is read (step S102). Further, the temperature T of the fluid flowing in the pipe 1-1 from the temperature sensor S2 (current temperature T of the fluid) is read (step S103).

  Then, from the current opening degree θ read in step S101, a flow coefficient Cv corresponding to the current opening degree θ is acquired as a current flow coefficient from the flow coefficient table TB1 in the memory 2-2 (step S104).

  Next, the CPU 2-1 adds the current differential pressure ΔP between the upstream and downstream of the valve body 1-2 read in step S102 to the flow rate calculation expression represented by the following equation (5), and the flow coefficient in step S104. The current flow coefficient Cv acquired from the table TB1 is substituted, and the flow rate of the fluid flowing through the pipe line 1-1 is obtained as the temporary flow rate Q ′ (step S105).

Q ′ = N · Cv · (ΔP) ^1/2 ... (5)
In this equation (5), N is a numerical constant.

  Next, the CPU 2-1 calculates the kinematic viscosity ν corresponding to the current temperature T of the fluid from the kinematic viscosity table TB3 in the memory 2-2 from the current temperature T of the fluid read in Step 103. Obtained as a viscosity (step S106).

Then, a ratio Q ′ / ν between the obtained current kinematic viscosity ν of the fluid and the provisional flow rate Q ′ obtained in step S105 is obtained as a current flow rate correction coefficient determination value f (step S107). From the flow rate correction coefficient determination value f = Q ′ / ν and the current opening degree θ read in step S101, the current opening degree θ and the current flow rate correction coefficient determination value f from the flow rate correction table TB4 in the memory 2-2. = Q '/ ν to obtain the flow rate correction factor F _R corresponding to (step S108).

Then, CPU 2-1 is a '(· F _R compensated flow Q Q = Q) by multiplying the' this acquired flow rate correction factor F _R temporary flow rate Q obtained at step S105 (step S109), the correction flow rate Q is displayed on the display unit 2-3 as a measured flow rate Qpv (step S110).

  Then, the CPU 2-1 reads the set flow rate Qsp from the host device, compares the measured flow rate Qpv with the set flow rate Qsp, and opens the valve element 1-2 so that the measured flow rate Qpv matches the set flow rate Qsp. θ is controlled (step S111). The CPU 2-1 repeats the processing operations in steps S <b> 101 to S <b> 111 at regular intervals.

In the first embodiment, since the kinematic viscosity ν corresponding to the current temperature T of the fluid is used for calculating the measured flow rate Qpv, the current opening θ of the valve element 1-2 and the current flow rate correction coefficient are used. Since the flow rate correction coefficient F _R obtained from the determined value f = Q ′ / ν is used, the flow rate of the fluid (liquid) can be measured with high accuracy, and the opening degree θ of the valve element 1-2 is controlled. Can be performed accurately.

  FIG. 5 shows a functional block diagram of the flow rate measuring unit 3 (3A) realized as a processing operation of the CPU 2-1. The flow rate measurement unit 3A includes a flow rate coefficient acquisition unit 3a, a flow rate calculation unit 3c, a kinematic viscosity acquisition unit 3d, a flow rate correction coefficient determination value calculation unit 3e, a flow rate correction coefficient acquisition unit 3f, and a flow rate correction unit 3g. It is composed of

  In the flow rate measurement unit 3A, the flow rate coefficient acquisition unit 3a receives the opening degree (current opening degree) θ of the valve body 1-2 from the opening degree sensor S3 as input, and from the flow rate coefficient table TB1 in the memory 2-2, The flow coefficient Cv corresponding to the current opening degree θ of the valve body 1-2 is acquired as the current flow coefficient.

  The flow rate calculation unit 3c includes the differential pressure (current differential pressure) ΔP between the upstream and downstream of the valve body 1-2 from the differential pressure sensor S1, and the current flow rate coefficient acquired by the flow rate coefficient acquisition unit 3a from the flow rate coefficient table TB1. Cv is used as an input, and the flow rate of the fluid flowing through the pipeline 1-1 is calculated as a temporary flow rate Q ′ according to the flow rate calculation formula represented by the above formula (5).

  The kinematic viscosity acquisition unit 3d receives the temperature (current temperature) T of the fluid from the temperature sensor S2 and inputs the kinematic viscosity ν corresponding to the temperature T of the fluid from the kinematic viscosity table TB3 in the memory 2-2. Obtained as kinematic viscosity. The flow rate correction coefficient determination value calculation unit 3e receives the temporary flow rate Q ′ obtained by the flow rate calculation unit 3c and the current kinematic viscosity ν acquired by the kinematic viscosity acquisition unit 3d from the kinematic viscosity table TB3 as inputs. The ratio Q ′ / ν between “and the current kinematic viscosity ν” is obtained as the current flow rate correction coefficient determination value f.

The flow rate correction coefficient acquisition unit 3f includes the opening degree (current opening degree) θ of the valve body 1-2 from the opening degree sensor S3, and the current flow rate correction coefficient determination value obtained by the flow rate correction coefficient determination value calculation unit 3e. With f = Q ′ / ν as an input, the flow rate correction coefficient F _R according to the current opening degree θ and the current flow rate correction coefficient determination value f = Q ′ / ν is obtained from the flow rate correction table TB4 in the memory 2-2. To get.

Flow rate correction section 3g is temporary flow rate Q obtained in the flow rate calculation unit 3c 'and inputs the flow rate correction factor F _R to the flow correction coefficient acquisition unit 3f is acquired from the flow correction table TB4, the temporary flow Q' flow correction in The provisional flow rate Q ′ is corrected by multiplying by the coefficient F _R to obtain a corrected flow rate Q (Q = Q ′ · F _R ). The corrected flow rate Q is output as the measured flow rate Qpv.

  In the first embodiment, the temporary flow rate Q ′ is used for the calculation of the current flow rate correction coefficient determination value f. This temporary flow rate Q ′ is the current differential pressure, as can be seen from the above equation (5). It can be said that the current flow rate correction coefficient determination value f = Q ′ / ν is obtained from information including the current differential pressure ΔP and the current kinematic viscosity ν. Further, the ratio Q ′ / ν between the temporary flow rate Q ′ of the fluid and the kinematic viscosity ν of the fluid corresponds to the Reynolds number, and the flow rate correction coefficient determination value calculation unit 3e obtains the Reynolds number as the current flow rate correction coefficient determination value f. It can be said that it is.

[Embodiment 2]
In the first embodiment, a flow coefficient table TB1 indicating the relationship between the opening degree θ of the valve body 1-2 and the flow coefficient Cv, and a kinematic viscosity table TB3 indicating the relationship between the fluid temperature T and the fluid kinematic viscosity ν, The ratio Q ′ / ν (flow rate correction coefficient determination value f) between the temporary flow rate Q ′ of the fluid created for each opening degree of the valve body 1-2 and the kinematic viscosity ν of the fluid and the flow rate correction coefficient (Reynolds number coefficient) was used and a flow rate correction table TB4 showing the relationship between F _R, in the second embodiment, the flow coefficient table TB1, kinematic viscosity table TB3, in addition to the flow correction table TB4, the temperature T and the fluid density of the fluid A density ratio table TB2 (see FIG. 6B) showing the relationship with the ratio ρ ₁ / ρ ₀ (ρ ₁ : fluid density at fluid temperature, ρ ₀ : fluid density at reference temperature) is used.

  Hereinafter, with reference to a flowchart shown in FIG. 7, processing operations unique to the present embodiment (second embodiment) executed by the CPU 2-1 of the actuator 2 according to a program stored in the memory 2-2 will be described. In the second embodiment, it goes without saying that the density ratio table TB2 is stored in the memory 2-2 together with the tables TB1, TB3 and TB4.

  The CPU 2-1 reads the opening degree θ (current opening degree θ) of the valve element 1-2 from the opening degree sensor S3 (step S201). Further, the differential pressure ΔP (current differential pressure ΔP) between the upstream and downstream of the valve body 1-2 from the differential pressure sensor S1 is read (step S202). Further, the temperature T (the current temperature T of the fluid) flowing in the pipeline 1-1 from the temperature sensor S2 is read (step S203).

  Then, from the current opening degree θ read in step S201, the flow coefficient Cv corresponding to the current opening degree θ is obtained as the current flow coefficient from the flow coefficient table TB1 in the memory 2-2 (step S204).

Further, from the current temperature T of the fluid read in step S203, the density ratio ρ ₁ / ρ ₀ corresponding to the current temperature T of the fluid is acquired as the current density ratio from the density ratio table TB2 in the memory 2-2. (Step S205).

Then, the CPU 2-1 adds the current differential pressure ΔP between the upstream and downstream of the valve element 1-2 read in step S202 to the flow rate calculation expression represented by the following formula (6), and the flow rate coefficient table in step S204. By substituting the current flow rate coefficient Cv acquired from TB1 and the current density ratio ρ ₁ / ρ ₀ acquired from the density ratio table TB2 in step S205, the flow rate of the fluid flowing through the pipeline 1-1 is set as the temporary flow rate Q. '(Step S206).

Q ′ = N · Cv · (ΔP / (ρ ₁ / ρ ₀ )) ^1/2 ... (6)
In this equation (6), N is a numerical constant.

  Next, the CPU 2-1 calculates the kinematic viscosity ν corresponding to the current temperature T of the fluid from the kinematic viscosity table TB3 in the memory 2-2 from the current temperature T of the fluid read in Step 103. Obtained as a viscosity (step S207).

Then, a ratio Q ′ / ν between the obtained current kinematic viscosity ν of the fluid and the provisional flow rate Q ′ obtained in step S206 is obtained as a current flow rate correction coefficient determination value f (step S208), and this obtained current value is obtained. From the flow rate correction coefficient determination value f = Q ′ / ν and the current opening degree θ read in step S201, the current opening degree θ and the current flow rate correction coefficient determination value f from the flow rate correction table TB4 in the memory 2-2. = Q '/ ν to obtain the flow rate correction factor F _R corresponding to (step S209).

Then, CPU 2-1 is a '(· F _R compensated flow Q Q = Q) by multiplying the' this acquired flow rate correction factor F _R temporary flow rate Q obtained in step S206 (step S210), the correction flow rate Q is displayed on the display unit 2-3 as a measured flow rate Qpv (step S211).

  Then, the CPU 2-1 reads the set flow rate Qsp from the host device, compares the measured flow rate Qpv with the set flow rate Qsp, and opens the valve element 1-2 so that the measured flow rate Qpv matches the set flow rate Qsp. θ is controlled (step S212). The CPU 2-1 repeats the processing operations in steps S201 to S112 at regular intervals.

In the second embodiment, the density ratio ρ ₁ / ρ ₀ and the kinematic viscosity ν corresponding to the current temperature T of the fluid are used to calculate the measured flow rate Qpv. Since the flow rate correction coefficient F _R obtained from the degree θ and the current flow rate correction coefficient determined value f = Q ′ / ν is used, the flow rate of the fluid (liquid) can be measured with high accuracy. The opening degree θ of −2 can be accurately controlled.

  FIG. 8 shows a functional block diagram of the flow rate measuring unit 3 (3B) realized as the processing operation of the CPU 2-1. The flow rate measurement unit 3B includes a flow rate coefficient acquisition unit 3a, a density ratio acquisition unit 3b, a flow rate calculation unit 3c, a kinematic viscosity acquisition unit 3d, a flow rate correction coefficient determination value calculation unit 3e, and a flow rate correction coefficient acquisition unit 3f. And a flow rate correction unit 3g.

In the flow rate measurement unit 3B, the flow rate coefficient acquisition unit 3a receives the opening degree (current opening degree) θ of the valve body 1-2 from the opening degree sensor S3 as input, and from the flow rate coefficient table TB1 in the memory 2-2, The flow coefficient Cv corresponding to the current opening degree θ of the valve body 1-2 is acquired as the current flow coefficient. The density ratio acquisition unit 3b receives the temperature (current temperature) T of the fluid from the temperature sensor S2, and from the density ratio table TB2 in the memory 2-2, the density ratio ρ ₁ corresponding to the current temperature T of the fluid. / Ρ ₀ is acquired as the current density ratio.

The flow rate calculation unit 3c includes the differential pressure (current differential pressure) ΔP between the upstream and downstream of the valve body 1-2 from the differential pressure sensor S1, and the current flow rate coefficient acquired by the flow rate coefficient acquisition unit 3a from the flow rate coefficient table TB1. Cv and the current density ratio ρ ₁ / ρ ₀ acquired from the density ratio table TB2 by the density ratio acquisition unit 3b are input, and according to the flow rate calculation expression expressed by the above equation (6), the pipeline 1-1 Is calculated as a temporary flow rate Q ′.

  The kinematic viscosity acquisition unit 3d receives the temperature (current temperature) T of the fluid from the temperature sensor S2 and inputs the kinematic viscosity ν corresponding to the temperature T of the fluid from the kinematic viscosity table TB3 in the memory 2-2. Obtained as kinematic viscosity. The flow rate correction coefficient determination value calculation unit 3e receives the temporary flow rate Q ′ obtained by the flow rate calculation unit 3c and the current kinematic viscosity ν acquired by the kinematic viscosity acquisition unit 3d from the kinematic viscosity table TB3 as inputs. The ratio Q ′ / ν between “and the current kinematic viscosity ν” is obtained as the current flow rate correction coefficient determination value f.

The flow rate correction coefficient acquisition unit 3f includes the opening degree (current opening degree) θ of the valve body 1-2 from the opening degree sensor S3, and the current flow rate correction coefficient determination value obtained by the flow rate correction coefficient determination value calculation unit 3e. With f = Q ′ / ν as an input, the flow rate correction coefficient F _R according to the current opening degree θ and the current flow rate correction coefficient determination value f = Q ′ / ν is obtained from the flow rate correction table TB4 in the memory 2-2. To get.

Flow rate correction section 3g is temporary flow rate Q obtained in the flow rate calculation unit 3c 'and inputs the flow rate correction factor F _R to the flow correction coefficient acquisition unit 3f is acquired from the flow correction table TB4, the temporary flow Q' flow correction in The provisional flow rate Q ′ is corrected by multiplying by the coefficient F _R to obtain a corrected flow rate Q (Q = Q ′ · F _R ). The corrected flow rate Q is output as the measured flow rate Qpv.

In the second embodiment, the temporary flow rate Q ′ is used to calculate the current flow rate correction coefficient determination value f. This temporary flow rate Q ′ is the current differential pressure, as can be seen from the above equation (6). Is information including ΔP and the current density ratio ρ ₁ / ρ ₀ , and the current flow rate correction coefficient determination value f = Q ′ / ν is the current differential pressure ΔP, the current density ratio ρ ₁ / ρ _0, and the current It can be said that it is obtained from information including kinematic viscosity ν. Further, the ratio Q ′ / ν between the temporary flow rate Q ′ of the fluid and the kinematic viscosity ν of the fluid corresponds to the Reynolds number, and the flow rate correction coefficient determination value calculation unit 3e obtains the Reynolds number as the current flow rate correction coefficient determination value f. It can be said that it is.

[Embodiment 3]
In Embodiment 1 described above, when the corrected flow rate Q is obtained by the flow rate correction unit 3g (FIG. 5), the corrected flow rate Q is immediately output as the measured flow rate Qpv. 'be replaced with the flow correction coefficient determination value f = Q in the flow correction coefficient determination value calculating unit 3e' calculation of / [nu, acquisition of the flow rate correction factor F _R in the flow correction coefficient acquisition unit 3f, the flow rate calculation in the flow correction unit 3g You may make it repeat correction | amendment with respect to temporary flow volume Q 'calculated | required in the part 3c as a brush-up process.

In the first embodiment, the correction flow rate Q is calculated as Q = Q ′ · F _R. This means that the measured flow rate Qpv is calculated as Q = Q ′ · F _R = N · Cv · (ΔP) ^1/2 · F _R. That is, suppose that Q obtained with F _R = 1 is Q ′, F _R is determined using Q ′, and Q is obtained using the determined F _R.

On the other hand, in the third embodiment, the corrected flow rate Q is replaced with the temporary flow rate Q ′, the flow rate correction coefficient determination value calculation unit 3e calculates the flow rate correction coefficient determination value f = Q ′ / ν, and the flow rate correction coefficient acquisition unit. obtaining a flow rate correction factor F _R in 3f, by repeating the correction to the temporary flow Q 'obtained by the flow rate calculation unit 3c in flow correction unit 3g, close the flow correction factor F _R to an appropriate value (see FIG. 9) Then, the measured flow rate Qpv is brought closer to the true value (see FIG. 10). In FIG. 10, the horizontal axis represents the number of corrections, and the vertical axis represents the flow rate.

  FIG. 11 shows a flowchart of a first example of the third embodiment executed by the CPU 2-1. In FIG. 11, the processing operations in steps S301 to S309 are the same as the processing operations in steps S101 to S109 in FIG.

When the CPU 2-1 obtains the corrected flow rate Q (Q = Q ′ · F _R ) (step S309), the count value N (number of corrections) is set to N = N + 1 (step S310), and the count value N is a predetermined value Nth. It is confirmed whether or not (N ≧ Nth) (step S311). Note that the initial value of the count value N is 0. Further, the predetermined value Nth is Nth> 1.

In this case, since N ≧ Nth is not satisfied (NO in step S311), the corrected flow rate Q obtained in step S309 is replaced with the temporary flow rate Q ′ (step S312), and the process returns to step S307. Thus, CPU 2-1, the flow rate correction coefficient calculation determinations f = Q '/ [nu at step S307, the acquisition of the flow rate correction factor F _R at step S308, and repeats the calculation of the correction flow rate Q in step S309.

  In the calculation of the corrected flow rate Q in step S309, the initial temporary flow rate Q ′ obtained in step S305 is used instead of the temporary flow rate Q ′ (previous corrected flow rate Q) replaced in step S312.

  The CPU 2-1 repeats the processes of steps S 307 to S 312 as a brush-up process, and when the count value N reaches the predetermined value Nth (YES in step S 311), the corrected flow rate Q at that time is displayed as the measured flow rate Qpv on the display unit 2-2. 3 (step S313), the opening degree θ of the valve element 1-2 is controlled so that the measured flow rate Qpv matches the set flow rate Qsp (step S314).

  FIG. 12 shows a flowchart of a second example of the third embodiment executed by the CPU 2-1. In FIG. 12, the processing operations in steps S401 to S409 are the same as the processing operations in steps S101 to S109 in FIG.

When the CPU 2-1 obtains the corrected flow rate Q (Q = Q ′ · F _R ) (step S409), the difference (Q _BF −Q _AF ) between the previous corrected flow rate Q _BF and the current corrected flow rate Q _AF is predetermined. It is confirmed whether or not the value is less than or equal to α (step S410).

In this case, since the previous corrected flow rate Q _BF does not exist at first, the CPU 2-1 determines that the difference (Q _BF −Q _AF ) between the previous corrected flow rate Q _BF and the current corrected flow rate Q _AF is less than or equal to the predetermined value α. The correction flow rate Q obtained in step S409 is replaced with the temporary flow rate Q ′ (step S411), and the process returns to step S407.

Thus, CPU 2-1, the flow rate correction coefficient calculation determinations f = Q '/ [nu at step S407, the acquisition of the flow rate correction coefficient F _R at step S408, and repeats the calculation of the correction flow rate Q in step S409. In calculating the corrected flow rate Q in step S409, the initial temporary flow rate Q ′ obtained in step S405 is used instead of the temporary flow rate Q ′ (previous corrected flow rate Q) replaced in step S411.

The CPU 2-1 repeats the processing of steps S 407 to S 411 as a brush-up process, and when the difference (Q _BF −Q _AF ) between the previous corrected flow rate Q _BF and the current corrected flow rate Q _AF becomes equal to or less than the predetermined value α ( YES in step S410), the corrected flow rate Q at that time is displayed as a measured flow rate Qpv on the display unit 2-3 (step S412), and the opening degree of the valve body 1-2 so that the measured flow rate Qpv matches the set flow rate Qsp. θ is controlled (step S413).

In this example, the difference between the previous corrected flow rate Q _BF and the current corrected flow rate Q _AF is obtained as “Q _BF −Q _AF ” in step S410, but it is obtained as | Q _AF −Q _BF |. It may be.

In a second example of the third embodiment, the flow correction coefficient F _R initially set to "1", so gradually decreases converged by bra Gerhard up process (see FIG. 9), this correction flow rate Q _AF Becomes smaller than the previous correction flow rate Q _BF . Therefore, “Q _BF −Q _AF ” is a positive value, and “Q _AF −Q _BF ” is a negative value. Therefore, when the predetermined value α is a positive value, the difference between the previous correction flow rate Q _BF and the current correction flow rate Q _AF is obtained as “Q _BF −Q _AF ” or as | Q _AF −Q _BF |. What should I do?

  FIG. 13 shows a functional block diagram of the flow rate measuring unit 3 (3C) in the third embodiment. The flow rate measurement unit 3C includes a repetition determination unit (repetition unit) 3h in addition to the configuration of the flow measurement unit 3A in the first embodiment (FIG. 5).

In the case of the first example of the third embodiment, the iterative determination unit 3h replaces the corrected flow rate Q from the flow rate correction unit 3g with the temporary flow rate Q ′, and the flow rate correction coefficient determination value f in the flow rate correction coefficient determination value calculation unit 3e. = Q '/ [nu calculation of obtaining the flow rate correction factor F _R in the flow correction coefficient acquisition unit 3f, the temporary flow rate Q obtained by the flow rate calculation unit 3c in the flow rate correction section 3 g' correction as a bra shoe up processing for flow rate correction The correction is repeated until the number of corrections N of the provisional flow rate Q ′ in the portion 3g reaches the predetermined number Nth.

In the case of the second example of the third embodiment, the iterative determination unit 3h replaces the corrected flow rate Q from the flow rate correction unit 3g with the temporary flow rate Q ′, and the flow rate correction coefficient determination value f in the flow rate correction coefficient determination value calculation unit 3e. = Q '/ [nu calculation of obtaining the flow rate correction factor F _R in the flow correction coefficient acquisition unit 3f, the temporary flow rate Q obtained by the flow rate calculation unit 3c in the flow rate correction section 3 g' correction as a bra shoe up processing for flow rate correction The process is repeated until the difference (Q _BF −Q _AF ) between the previous corrected flow rate Q _BF and the current corrected flow rate Q _AF in the portion 3g becomes equal to or less than a predetermined value α.

[Embodiment 4]
In the third embodiment, similarly to the second embodiment, a density ratio table TB2 may be used in addition to the flow coefficient table TB1, the kinematic viscosity table TB3, and the flow rate correction table TB4. FIG. 14 is a flowchart corresponding to FIG. 11 when the density ratio table TB2 is used, and FIG. 15 is a flowchart when the density ratio table TB2 is used as a flowchart of the first example of the fourth embodiment. 12 is shown as a flowchart of the second example of the fourth embodiment. FIG. 16 shows a functional block diagram of the flow rate measurement unit 3 (3D) in the fourth embodiment.

In the flow rate measurement unit 3D of the fourth embodiment, the flow rate calculation unit 3c includes a differential pressure (current differential pressure) ΔP between the upstream and downstream of the valve body 1-2 from the differential pressure sensor S1, and a flow coefficient acquisition unit 3a. Is input from the current flow coefficient Cv acquired from the flow coefficient table TB1 and the current density ratio ρ ₁ / ρ ₀ acquired from the density ratio table TB2 by the density ratio acquisition unit 3b, and is expressed by the above equation (6). In accordance with the flow rate calculation formula, the flow rate of the fluid flowing through the pipeline 1-1 is calculated as the temporary flow rate Q ′. The flow rate correction coefficient determination value calculation unit 3e receives the temporary flow rate Q ′ obtained by the flow rate calculation unit 3c and the current kinematic viscosity ν acquired by the kinematic viscosity acquisition unit 3d from the kinematic viscosity table TB3 as inputs. The ratio Q ′ / ν between “and the current kinematic viscosity ν” is obtained as the current flow rate correction coefficient determination value f.

[Embodiment 5]
In the third embodiment, close the flow correction coefficient F _R by repeating the bra Gerhard up process to an appropriate value, the flow rate measured Qpv was to go closer to the true value, in the process of Embodiment 5 in one , the flow rate correction factor F _R to a proper value, so as to obtain a value close to the true value as the measurement flow rate QPV. That is, the fifth embodiment does not require repeated calculation as in the third embodiment.

  FIG. 17 shows a flowchart of the fifth embodiment executed by the CPU 2-1. In FIG. 17, the processing operations in steps S701 to S706 are the same as the processing operations in steps S101 to S106 in FIG.

In the fifth embodiment, a flow rate correction table TB4 ′ as shown in FIG. 18 is used instead of the flow rate correction table TB4 (FIG. 2C) used in the first embodiment. The flow correction table TB4 'shows the relationship between the flow rate correction coefficient determination value is created for each opening f = (ΔP) ^1/2 / ν and the flow correction factor F _R of the valve body 1-2.

When the CPU 2-1 acquires the kinematic viscosity ν corresponding to the current temperature T of the fluid from the kinematic viscosity table TB3 in the memory 2-2 as the current kinematic viscosity of the fluid (step S706), the valve body read in step S702 The current flow rate correction coefficient determination value f = (ΔP) ^1/2 / ν is obtained from the current differential pressure ΔP between the upstream and downstream of 1-2 and the current kinematic viscosity ν of the fluid obtained in step S706 (step S706). S707).

The current flow rate correction coefficient determined value f = (ΔP) ^1/2 / ν and the current opening degree θ read in step S701 are used to determine the current flow rate correction table TB4 ′ in the memory 2-2. obtaining the flow rate correction factor F _R corresponding to the opening degree θ and the current flow rate correction coefficient determination value ^{f = (ΔP) 1/2 / ν} ( step S 708).

Then, CPU 2-1 corrects the a correction flow rate Q (Q = Q '· F _R)' temporary flow rate Q by multiplying the 'this acquired flow rate correction factor F _R temporary flow rate Q obtained in step S705 (Step S709), the corrected flow rate Q is displayed as a measured flow rate Qpv on the display unit 2-3 (Step S710), and the opening θ of the valve element 1-2 is set so that the measured flow rate Qpv matches the set flow rate Qsp. Control is performed (step S711). The CPU 2-1 repeats the processing operations in steps S 701 to S 711 at regular intervals.

In the fifth embodiment, since the kinematic viscosity ν corresponding to the current temperature T of the fluid is used for calculating the measured flow rate Qpv, the current opening θ of the valve element 1-2 and the current flow rate correction coefficient are used. Since the flow rate correction coefficient F _R obtained from the determined value f = (ΔP) ^1/2 / ν is used, the flow rate of the fluid (liquid) can be measured with higher accuracy than in the first embodiment, The opening degree θ of the valve body 1-2 can be controlled more accurately.

  FIG. 19 shows a functional block diagram of the flow rate measuring unit 3 (3E) in the fifth embodiment. The flow rate measurement unit 3E is replaced with a flow rate correction coefficient determination value calculation unit 3e and a flow rate correction coefficient acquisition unit 3f in the flow rate measurement unit 3A (FIG. 5) according to the first embodiment. And a flow rate correction coefficient acquisition unit 3f ′.

In the flow rate measurement unit 3E, the flow rate correction coefficient determination value calculation unit 3e ′ includes a differential pressure (current differential pressure) ΔP between the upstream and downstream of the valve body 1-2 from the differential pressure sensor S1, and a kinematic viscosity acquisition unit 3d. The current kinematic viscosity ν obtained from the kinematic viscosity table TB3 is used as an input, and the current flow rate correction coefficient determination value f = (ΔP) ^1/2 / ν is obtained.

The flow rate correction coefficient acquisition unit 3f ′ includes the opening degree (current opening degree) θ of the valve body 1-2 from the opening degree sensor S3, and the current flow rate correction coefficient obtained by the flow rate correction coefficient determination value calculation unit 3e ′. The determined value f = (ΔP) ^1/2 / ν is input, and the current opening θ and the current flow rate correction coefficient determined value f = (ΔP) ^{1 / are obtained} from the flow rate correction table TB4 ′ in the memory 2-2. obtaining the flow rate correction factor F _R corresponding to ² / [nu.

Flow rate correction section 3g is' a flow rate correction coefficient acquisition unit 3f flow rate correction table TB4 'temporary flow rate Q obtained in the flow rate calculation unit 3E as input flow rate correction factor F _R obtained from the flow rate in the temporary flow rate Q' The provisional flow rate Q ′ is corrected by multiplying the correction coefficient F _R to obtain a corrected flow rate Q (Q = Q ′ · F _R ). The corrected flow rate Q is output as the measured flow rate Qpv.

[Embodiment 6]
Also in the fifth embodiment, as in the fourth embodiment, a density ratio table TB2 may be used in addition to the flow coefficient table TB1, the kinematic viscosity table TB3, and the flow correction table TB4. FIG. 20 shows a flowchart corresponding to FIG. 17 in the case of using the density ratio table TB2 as a flowchart of the sixth embodiment. FIG. 21 shows a functional block diagram of the flow rate measurement unit 3 (3F) in the sixth embodiment.

In the sixth embodiment, a flow rate correction table TB4 ″ as shown in FIG. 22 is used instead of the flow rate correction table TB4 ′ (FIG. 18) used in the fifth embodiment. This flow rate correction table TB4 ″. the flow rate correction coefficient determination value f = (ΔP) ^1/2 / created for each opening of the valve body _{1-2 (ν (ρ 1 / ρ} 0) 1/2) and the flow rate correction coefficient F _R Showing the relationship.

In the flow rate measurement unit 3F, the flow rate correction coefficient determination value calculation unit 3e ′ includes a differential pressure (current differential pressure) ΔP between the upstream and downstream of the valve body 1-2 from the differential pressure sensor S1, and a density ratio acquisition unit 3b. Is input from the current density ratio ρ ₁ / ρ ₀ acquired from the density ratio table TB2 and the current kinematic viscosity ν acquired from the kinematic viscosity table TB3 by the kinematic viscosity acquiring unit 3d, and the current flow correction coefficient determination value f = (ΔP) ^1/2 / (ν (ρ ₁ / ρ ₀ ) ^1/2 )

The flow rate correction coefficient acquisition unit 3f ′ includes the opening degree (current opening degree) θ of the valve body 1-2 from the opening degree sensor S3, and the current flow rate correction coefficient obtained by the flow rate correction coefficient determination value calculation unit 3e ′. The determined value f = (ΔP) ^1/2 / (ν (ρ ₁ / ρ ₀ ) ^1/2 ) is used as an input, and the current opening θ and the current value are obtained from the flow rate correction table TB4 ″ in the memory 2-2. obtaining the flow rate correction factor F _R corresponding to = flow rate correction coefficient determination value ^{f (ΔP) 1/2 / (ν} (ρ 1 / ρ 0) 1/2).

Flow rate correction section 3g is' a flow rate correction coefficient acquisition unit 3f flow rate correction table TB4 'temporary flow rate Q obtained in the flow rate calculation unit 3c as input flow rate correction factor F _R obtained from the flow rate in the temporary flow rate Q' The provisional flow rate Q ′ is corrected by multiplying the correction coefficient F _R to obtain a corrected flow rate Q (Q = Q ′ · F _R ). The corrected flow rate Q is output as the measured flow rate Qpv.

[Embodiment 7]
FIG. 23 is a diagram showing an outline of an embodiment (Embodiment 7) of a system in which a flow measuring device according to the present invention is connected to a flow control valve. 1, the same reference numerals as those in FIG. 1 denote the same or equivalent components as those described with reference to FIG. 1, and the description thereof will be omitted.

  In the seventh embodiment, the flow measuring device 5 is connected to the flow control valve 101, and the fluid (liquid) flowing in the pipe 1-1 of the flow control valve 101 in the flow measuring device 5 as in the first embodiment. ) Is calculated (measured flow rate Qpv).

  In the seventh embodiment, the actuator 4 in the flow control valve 101 includes a CPU 4-1, a memory 4-2, and a motor 4-3. The opening degree θ of the valve body 1-2 detected by the degree sensor S3, the measured flow rate Qpv from the flow rate measuring device 5, and the set flow rate Qsp from the host device are given.

  In addition, the flow rate measuring device 5 includes a CPU 5-1, a memory 5-2, a display unit 5-3, and an interface 5-4. 4, the current differential pressure ΔP between the upstream and downstream of the valve body 1-2 detected by the differential pressure sensor S1, the fluid temperature T detected by the temperature sensor S2, and the valve body 1 detected by the opening sensor S3. An opening degree θ of −2 is given.

The memory 5-2 of the flow rate measuring device 5 stores the flow rate coefficient table TB1, the density ratio table TB2, the kinematic viscosity table TB3, and the flow rate correction table TB4 as in the first embodiment, and is shown in FIG. Q = Q ′ · F _{R in the same} manner as in the first embodiment by causing the CPU 5-1 to perform the processing operations of steps S901 to S909 shown (processing operations corresponding to steps S101 to S109 shown in FIG. 4). The correction flow rate Q is obtained as follows.

  The CPU 5-1 displays the corrected flow rate Q on the display unit 5-3 as the measured flow rate Qpv (step S910) and sends it to the actuator 4 of the flow rate control valve 101 via the interface 5-4 (step S911). The CPU 5-1 repeats the processing operations in steps S901 to S911 at regular intervals.

  When the measured flow rate Qpv is sent from the flow rate measuring device 5, the CPU 4-1 of the actuator 4 compares the sent measured flow rate Qpv with the set flow rate Qsp, and the measured flow rate Qpv matches the set flow rate Qsp. Thus, the opening degree θ of the valve body 1-2 is controlled. The control of the opening degree θ is performed according to a program stored in the memory 4-2.

  In the seventh embodiment described above, the flow measurement device 5 is caused to perform the same processing as in the first embodiment, but may be configured to perform the same processing as in the second to sixth embodiments. Needless to say.

For reference, FIG. 25 shows a flowchart in a case where the flow rate measuring device 5 is made to perform the same processing as in the second embodiment. In this case, in step S1005, the density ratio ρ ₁ / ρ ₀ corresponding to the current temperature T of the fluid is acquired as the current density ratio from the density ratio table TB2, and in step S1006, the density ratio is expressed by the above-described equation (6). The current differential pressure ΔP between the upstream and downstream of the valve element 1-2 read in step S1002, the current flow coefficient Cv acquired from the flow coefficient table TB1 in step S1004, and the density ratio in step S1005 By substituting the current density ratio ρ ₁ / ρ ₀ obtained from the table TB2, the flow rate of the fluid flowing through the pipe line 1-1 is obtained as the temporary flow rate Q ′.

  In the first to seventh embodiments described above, the differential pressure sensor S1 is provided to detect the differential pressure ΔP between the upstream and downstream of the valve body 1-2, but the upstream pressure of the valve body 1-2. And the pressure on the downstream side are detected by separate pressure sensors, and the pressure difference ΔP between the upstream and downstream of the valve body 1-2 is determined from the pressure from the upstream pressure sensor and the pressure from the downstream pressure sensor. You may make it ask.

  In the first to seventh embodiments described above, the flow coefficient table TB1 and the like are provided as a data table. However, an approximate expression may be used instead of the data table. In the present invention, the table definition includes an approximate expression.

  The present applicant has previously proposed a gas flow rate measuring apparatus as Patent Document 3. In this gas flow rate measuring device, it is possible to measure the gas flow rate with high accuracy by performing non-turbulent flow correction using a flow rate correction table showing the relationship of the Reynolds number coefficient to the ratio of gas flow rate and kinematic viscosity. .

Specifically, in Patent Document 3, a YC linear table and a flow rate correction table are stored in a memory, and the current YC is calculated from the opening degree θ and the differential pressure ratio x = ΔP / P1 between the upstream and the downstream from the YC linear table. The obtained YC value, the differential pressure ratio x = ΔP / P1, the molar mass M, and the gas temperature T1 are substituted into the flow rate calculation formula to obtain the current gas flow rate Q ′ (before the non-turbulent flow correction). Calculated flow rate), kinematic viscosity ν is calculated from the gas temperature, Q ′ / ν is obtained, and the Reynolds number coefficient F _R at that time is obtained from the flow rate correction table from Q ′ / ν and opening degree θ, The Reynolds number coefficient F _R is used as a flow rate correction coefficient, and a gas flow rate Q subjected to non-turbulent flow correction is obtained as Q = F _R · Q ′.

  Since the method shown in Patent Document 3 uses the fluid to be measured as a gas, the present invention in which the fluid to be measured is a liquid (incompressible fluid) is completely different from the logic for obtaining the flow rate. Is different. Therefore, the method disclosed in Patent Document 3 does not suggest the present invention.

[Extension of the embodiment]
The present invention has been described above with reference to the embodiment. However, the present invention is not limited to the above embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the technical idea of the present invention. Each embodiment can be implemented in any combination within a consistent range.

  DESCRIPTION OF SYMBOLS 1 ... Valve main body, 1-1 ... Pipe line, 1-2 ... Valve body, 2 ... Actuator, 2-1 ... CPU, 2-2 ... Memory, 2-3 ... Display part, 2-4 ... Motor, S1 ... Differential pressure sensor, S2 ... Temperature sensor, S3 ... Opening degree sensor, 3 (3A to 3F) ... Flow rate measurement unit, 3a ... Flow rate coefficient acquisition unit, 3b ... Density ratio acquisition unit, 3E ... Flow rate calculation unit, 3d ... Kinematic viscosity Acquisition unit, 3e, 3e '... flow rate correction coefficient determination value calculation unit, 3f, 3f' ... flow rate correction coefficient acquisition unit, 3g ... flow rate correction unit, 3h ... repetition determination unit, 4 ... actuator, 4-1 ... CPU, 4 -2 ... Memory, 4-3 ... Motor, 5 ... Flow rate measuring device, 5-1 ... CPU, 5-2 ... Memory, 5-3 ... Display unit, 5-4 ... Interface, 100, 101 ... Flow control valve, TB1 ... flow coefficient table (Cv table), TB2 ... density ratio table, TB3 ... Viscosity table, TB4, TB4 ', TB4 "... flow rate correction table.

Claims (11)

In the flow rate measuring device for measuring the flow rate of the fluid controlled by adjusting the opening degree of the valve body, the fluid to be measured is a liquid,
A flow coefficient table storage unit for storing a flow coefficient table indicating a relationship between the opening degree of the valve body and the flow coefficient;
A flow coefficient acquisition unit that acquires a flow coefficient according to the current opening of the valve body as a current flow coefficient from the flow coefficient table;
A flow rate calculation unit for obtaining a flow rate of the fluid as a temporary flow rate from a current differential pressure between the upstream and downstream of the valve body and a current flow rate coefficient acquired from the flow rate coefficient table;
A kinematic viscosity table storage unit for storing a kinematic viscosity table indicating a relationship between the temperature of the fluid and the kinematic viscosity of the fluid;
A flow rate correction table storage unit for storing a flow rate correction table indicating a relationship between a flow rate correction coefficient created for each opening of the valve body and a flow rate correction coefficient determination value corresponding to the flow rate correction coefficient;
A kinematic viscosity acquisition unit that acquires the kinematic viscosity according to the current temperature of the fluid as the current kinematic viscosity from the kinematic viscosity table;
A flow rate correction coefficient determination value calculation unit for determining a current flow rate correction coefficient determination value from information including the current differential pressure between the upstream and downstream of the valve body and the current kinematic viscosity acquired from the kinematic viscosity table;
A flow rate correction coefficient acquisition unit that acquires a flow rate correction coefficient according to a current flow rate correction coefficient determination value obtained by the current opening degree of the valve body and the flow rate correction coefficient determination calculation unit from the flow rate correction table;
And a flow rate correction unit that corrects the temporary flow rate obtained by the flow rate calculation unit by multiplying the temporary flow rate by the flow rate correction coefficient acquired by the flow rate correction coefficient acquisition unit to obtain a corrected flow rate. Flow measurement device. The flow rate measuring device according to claim 1,
A density ratio table storage unit for storing a density ratio table indicating a relationship between the temperature of the fluid and the density ratio of the fluid;
A density ratio acquisition unit that acquires, as the current density ratio, a density ratio according to the current temperature of the fluid from the density ratio table;
The flow rate calculator is
From the current differential pressure between the upstream and downstream of the valve body, the current flow coefficient acquired from the flow coefficient table, and the current density ratio acquired from the density ratio table, the flow rate of the fluid is used as a temporary flow rate. Seeking
The flow rate correction coefficient determination value calculation unit is
Current flow rate correction coefficient based on information including current differential pressure between upstream and downstream of the valve body, current density ratio acquired from the density ratio table, and current kinematic viscosity acquired from the kinematic viscosity table A flow rate measuring device characterized by obtaining a determined value. The flow rate measuring device according to claim 1,
The flow rate calculator is
From the current differential pressure between the upstream and downstream of the valve body and the current flow coefficient acquired from the flow coefficient table, the flow rate of the fluid is obtained as a temporary flow rate Q ′ by the following equation (1). Flow rate measuring device.
Q ′ = N · Cv · (ΔP) ^1/2 ... (1)
However, ΔP is a differential pressure between the upstream and downstream of the valve body, Cv is a flow coefficient, and N is a numerical constant. In the flow measurement device according to claim 2,
The flow rate calculator is
From the current differential pressure between the upstream and downstream of the valve body, the current flow coefficient obtained from the flow coefficient table, and the current density ratio obtained from the density ratio table, the following equation (2) A flow rate measuring device characterized in that a flow rate of a fluid is obtained as a temporary flow rate Q ′.
Q ′ = N · Cv · (ΔP / (ρ ₁ / ρ ₀ )) ^1/2 ... (2)
Where ΔP is the differential pressure between the upstream and downstream of the valve body, Cv is the flow coefficient, ρ ₁ / ρ ₀ is the fluid density ratio (ρ ₁ : fluid density at fluid temperature, ρ ₀ : fluid density at reference temperature ), N is a numerical constant. The flow rate measuring device according to claim 1,
The flow rate correction table storage unit
Storing the flow rate correction table having a value f expressed by the following equation (3) as a flow rate correction coefficient determination value;
The flow rate correction coefficient determination value calculation unit is
From the current differential pressure between the upstream and downstream of the valve body and the current kinematic viscosity obtained from the kinematic viscosity table, a current flow rate correction coefficient determination value is obtained as a value f expressed by the following equation (3). The flow rate measuring device characterized by: f = (ΔP) ^1/2 / ν (3)
Where ΔP is the differential pressure between the upstream and downstream of the valve body, and ν is the kinematic viscosity of the fluid. In the flow measurement device according to claim 2,
The flow rate correction table storage unit
Storing the flow rate correction table having a value f expressed by the following equation (4) as a flow rate correction coefficient determination value;
The flow rate correction coefficient determination value calculation unit is
From the current differential pressure between the upstream and downstream of the valve body, the current density ratio acquired from the density ratio table, and the current kinematic viscosity acquired from the kinematic viscosity table, the following equation (4) is used. The current flow rate correction coefficient determination value is obtained as the value f to be calculated f = (ΔP) ^1/2 / (ν (ρ ₁ / ρ ₀ ) ^1/2 ) (4) )
Where ΔP is the differential pressure between the upstream and downstream of the valve body, ν is the kinematic viscosity of the fluid, ρ ₁ / ρ ₀ is the fluid density ratio (ρ ₁ : fluid density at fluid temperature, ρ ₀ : fluid at reference temperature Density). In the flow measuring device according to any one of claims 1 to 4,
The flow rate correction table storage unit
Storing the flow rate correction table having a ratio between the temporary flow rate of the fluid and the kinematic viscosity of the fluid as the flow rate correction coefficient determination value;
The flow rate correction coefficient determination value calculation unit is
A flow rate measuring device characterized in that a ratio between the temporary flow rate obtained by the flow rate calculation unit and the current kinematic viscosity obtained from the kinematic viscosity table is obtained as the current flow rate correction coefficient determination value. The flow rate measuring device according to claim 7,
Replacing the corrected flow rate from the flow rate correction unit with the temporary flow rate, calculating the flow rate correction coefficient determination value in the flow rate correction coefficient determination value calculation unit, acquiring the flow rate correction coefficient in the flow rate correction coefficient acquisition unit, the flow rate correction unit A flow rate measuring device comprising: a repeating unit that repeats the correction for the temporary flow rate obtained by the flow rate calculation unit in a brush-up process. The flow rate measuring device according to claim 8,
The repeating part is
The flow rate measuring device, wherein the brush-up process is repeated until the number of corrections of the temporary flow rate in the flow rate correction unit reaches a predetermined number. The flow rate measuring device according to claim 8,
The repeating part is
The flow rate measuring apparatus, wherein the brush-up process is repeated until a difference between a previous corrected flow rate and a current corrected flow rate in the flow rate correction unit becomes a predetermined value or less.   A flow rate control valve incorporating the flow rate measuring device according to claim 1.

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