Automatic flow rate control device and method therefore

Abstract

The present invention relates to an automatic flow rate control device and a control method thereof, and more specifically, to an automatic flow control device and a control method thereof that automatically controls the transfer flow rate of a liquid using a scale and a pump.

Description

Technology Field

[0001] The present invention relates to an automatic flow rate control device and a control method thereof, and more specifically, to an automatic flow control device and a control method thereof that automatically controls the transfer flow rate of a liquid using a scale and a pump. Background Technology

[0003] FIG. 1 is a diagram illustrating the configuration of a conventional flow control system. Referring to FIG. 1, the flow control system is a system provided for the transmission (or supply) of a target flow rate and for changing the flow rate, and generally includes a flow meter, a flow control valve, and a control means for controlling the operation thereof.

[0004] The operation of the flow control system is performed by a method in which the control means compares the flow rate detected by the flow meter with the target flow rate to control the opening of the flow control valve.

[0005] Flow control systems are used across various industries, including automotive, semiconductor, plant, chemical, and bio sectors, and the precision required for flow control continues to increase with the advancement of these industries.

[0006] For this reason, various studies have been continuously conducted on each of the flow meters, flow control valves, and control means that constitute a flow control system; however, as precision increases, it leads to an increase in system prices, which acts as a significant burden on the industry as a whole.

[0007] However, conventionally, installing flow meters to control the flow rate of organic solvents, solutions, etc., in small-scale or low-flow ranges presented the problem of excessive costs. Furthermore, conventional flow control systems without flow meters had the issue of requiring a user to be constantly present to adjust pump settings in response to changes in transfer flow rates caused by experimental conditions and mechanical variations of the pump.

[0008] Therefore, there is a need to improve the flow control system so that it can be used in small-scale or low-flow ranges, and so that the system automatically changes the pump's setpoints, thereby increasing research productivity by reducing on-site personnel. Prior art literature

[0010] Korean Registered Patent No. 10-1028154 Korean Registered Patent No. 10-1021984 The problem to be solved

[0011] The present invention has been devised to solve the aforementioned problems, and the objective of the present invention is to provide an automatic flow rate control device and a control method thereof that automatically controls the flow rate of a liquid transferred without using a flow meter, through the flow rate control precision of a pump, the measurement precision of a scale, and the elapsed time of flow rate measurement.

[0012] In addition, the objective of the present invention is to provide an automatic flow rate control device and a control method thereof, which increase productivity by reducing the number of personnel stationed for flow rate control. means of solving the problem

[0014] A linear flow rate automatic control device according to the present invention comprises a storage unit for storing a liquid raw material; and a time elapsed for measuring the weight and flow rate of the liquid raw material stored in the storage unit (△t=t n A measuring unit for measuring -t0); a time interval (t) for measuring the weight of the liquid raw material. step ) and an input unit for inputting an initial pump flow rate setting value; and receiving data from the storage unit, measurement unit, and input unit to input a pump flow rate setting value (Q set,new It includes a control unit that generates a pump control signal by changing ), and the control unit is characterized by calculating the relationship between the flow rate fluctuation range and the measured flow rate and the target flow rate according to the following mathematical formulas 1 and 2.

[0015] [Mathematical Formula 1]

[0016]

[0017] [Mathematical Formula 2]

[0018]

[0019] Here, Tol: flow rate fluctuation (gradually decreasing over time), R F : Ratio of actual measured flow rate to target flow rate (F mes / F set ), Res p : Pump flow control precision (ml / min), F set : Target flow rate (g / min), Res b : Balance measurement precision (g), d: Density of liquid raw material (g / ml), α, β, γ: Factors applied to Tol calculation formula (0 < α < 10, 0 < β < 50, 0 < γ < 10), C: Factor applied to Tol calculation formula (0 <C<1000), t n : Flow rate measurement time, where n is an integer greater than or equal to 1

[0020] In one embodiment, the control unit is characterized by calculating the flow rate according to the change in weight of the liquid raw material during the flow rate measurement time.

[0021] [Mathematical Formula 3]

[0022]

[0023] Here, F mes : Measured flow rate (g / min), △t: Flow rate measurement time range (cumulative flow rate measurement time, t n -t0, Here, n is an integer greater than or equal to 1) △m: change in scale weight during △t((t n Balance value at time, m n )-(scale value at time t0, m0))

[0024] In one embodiment, the control unit is characterized by changing the pump flow rate setting value if the mathematical formula 2 is greater than the flow rate fluctuation range.

[0025] In one embodiment, the control unit is characterized by changing the pump control signal by changing the pump flow rate setting value according to the following mathematical formula 4.

[0026] [Mathematical Formula 4]

[0027]

[0028] Here, Q set,new : Pump flow rate set value (ml / min), Q set,old : Q set,new Previously set pump flow rate setting (ml / min), R F : Ratio of actual measured flow rate to target flow rate (F mes / F set ), ω: weight (0 < ω < 1), n: integer greater than or equal to 1

[0029] In one embodiment, the control unit is characterized by controlling the pump to maintain the flow rate by calculating the flow rate according to the change in weight of the storage unit during the flow rate measurement time when the mathematical formula 2 is smaller than the flow rate fluctuation range.

[0030] A linear flow rate automatic control method according to the present invention comprises: a step of setting an initial input value in an input unit and operating a pump according to the input value; a step of a measuring unit measuring the cumulative time at which the liquid raw material in a storage unit begins to decrease and the weight of the liquid raw material under conditions corresponding to the input value; a step of a control unit receiving data measured by the measuring unit and calculating a flow rate through the ratio of the weight change of the liquid raw material during the cumulative time; a step of the control unit calculating a flow rate fluctuation range and a relationship between the measured flow rate and the target flow rate according to the input value and the flow rate; and a step of the control unit changing the input value or controlling the pump according to the absolute value of the relationship between the measured flow rate and the target flow rate and the magnitude of the flow rate fluctuation range.

[0031] In one embodiment, the initial input value is characterized by including one or more of the following: an input target flow rate, the density of the liquid raw material, the pump flow rate control precision, the time interval for measuring the weight of the liquid raw material, and the average flow rate measurement time range.

[0032] In one embodiment, the step of changing the input value or controlling the pump comprises: a step in which the control unit changes the input value if the absolute value of the relationship between the measured flow rate and the target flow rate is greater than the flow rate fluctuation range; and a step in which the control unit controls the pump to maintain the flow rate calculated by the control unit if the absolute value of the relationship between the measured flow rate and the target flow rate is less than the flow rate fluctuation range.

[0033] In one embodiment, the step of controlling the pump comprises an average flow rate measurement time range (t) in which the control unit calculates the absolute value of the relationship between the measured flow rate and the target flow rate and the flow rate fluctuation range, wherein the measurement time range is arbitrarily set. avg It is characterized by maintaining the above pump flow rate setting value until it reaches ).

[0034] In one embodiment, the average flow rate measurement time range is characterized as being 1 minute to 30 minutes. Effects of the invention

[0036] According to the present invention, the liquid transfer flow rate is automatically controlled through the flow rate control precision of a pump, the measurement precision of a scale, and the elapsed time of flow rate measurement without using a flow meter, thereby enabling the liquid flow rate to be accurately controlled at a relatively low cost.

[0037] In addition, the reduction in personnel stationed for flow control results in increased productivity. Brief explanation of the drawing

[0039] Figure 1 is a diagram illustrating the configuration of a conventional flow control system. FIG. 2 is a diagram illustrating the configuration of an automatic flow rate control device according to one embodiment of the present invention. FIG. 3 is a flowchart illustrating the procedure for controlling the flow rate according to the present invention. Specific details for implementing the invention

[0040] The detailed description of the present invention is intended to fully explain the invention to those skilled in the art. Throughout the specification, when a part is described as “comprising” a certain component or “featuring” a certain structure and shape, this does not mean that other components are excluded or other structures and shapes are excluded unless specifically stated otherwise, but rather that other components, structures, and shapes may be included.

[0041] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are presented and described in detail in the detailed description. However, this is not intended to limit the scope of the invention by the embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0043] FIG. 2 is a diagram illustrating the configuration of an automatic flow rate control device (100) according to one embodiment of the present invention.

[0044] The flow rate automatic control device (100) includes a storage unit (10), a measurement unit (20), an input unit (30), and a control unit (40).

[0045] The storage unit (10) is a raw material storage container for storing liquid raw materials. The storage unit (10) may include a raw material supply pipe for supplying liquid raw materials to a pump.

[0047] The measuring unit (20) measures the weight and time of the liquid raw material stored in the storage unit (10). Accordingly, the storage unit (10) can be positioned above the measuring unit (20).

[0048] The measuring unit (20) may include a liquid crystal display (display) that indicates the weight of the storage unit (10) and the elapsed time (△t) of the weight of the storage unit (10), and a reset button that resets the weight and time.

[0049] The measuring unit (20) can measure time from the time the pump starts operating and calculate the accumulated time after the time interval for measuring the weight of the liquid raw material input to the input unit (30) described later has elapsed. Additionally, the measuring unit (20) can calculate the change in weight of the liquid raw material during the elapsed time for measuring the weight of the liquid raw material.

[0051] The input unit (30) is configured to input initial setting values ​​for calculating the flow rate fluctuation range described later. For example, the initial setting values ​​include an initial pump flow rate setting value, a density (d) of the liquid raw material, and a flow rate measurement value (F mes The time interval (t) for measuring the weight of the liquid raw material to calculate the ) and the flow rate fluctuation range (Tol). step It may include ) etc.

[0053] The control unit (40) is electrically connected to the storage unit (10), the measurement unit (20), the input unit (30), and the pump, and is configured to receive data from the storage unit (10), the measurement unit (20), and the input unit (30) for flow rate measurement.

[0054] Furthermore, the control unit (40) receives the liquid raw material weight change, elapsed time, pump flow rate control precision, scale measurement precision, etc., from the storage unit (10), measurement unit (20), and input unit (30), and the pump flow rate setting value (Q set,new ), flow rate fluctuation range (Tol), and the relationship between the measured flow rate and the target flow rate can be calculated.

[0055] To calculate the flow rate fluctuation range (Tol), the control unit (40) is configured to calculate the flow rate fluctuation range (Tol) based on the following mathematical formula.

[0056] [Mathematical Formula 1]

[0057]

[0058] Here, Tol: flow rate fluctuation (gradually decreasing over time), R F : Ratio of actual measured flow rate to target flow rate (F mes / F set), Res p : Pump flow control precision (ml / min), F set : Target flow rate (g / min), Res b : Balance measurement precision (g), d: Density of liquid raw material (g / ml), α, β, γ: Factors applied to Tol calculation formula (0 < α < 10, 0 < β < 50, 0 < γ < 10), C: Factor applied to Tol calculation formula (0 <C<1000), t n : Flow rate measurement time, where n is an integer greater than or equal to 1

[0059] And, in order to calculate the relationship between the measured flow rate and the target flow rate, the control unit (40) is configured to calculate the relationship between the measured flow rate and the target flow rate based on the following mathematical formula.

[0060] [Mathematical Formula 2]

[0061]

[0062] Here, R F : Ratio of actual measured flow rate to target flow rate (F mes / F set )

[0063] And, to calculate the flow rate, the control unit (40) is configured to calculate the flow rate based on the following mathematical formula.

[0064] [Mathematical Formula 3]

[0065]

[0066] Here, F mes : Measured flow rate (g / min), △t: Flow rate measurement time range (cumulative flow rate measurement time, t n -t0, where n is an integer greater than or equal to 1) △m: change in scale weight during △t((t n Balance value at time, m n )-(scale value at time t0, m0))

[0067] In other words, the flow rate can be calculated based on the change in weight of the liquid raw material during the flow rate measurement time.

[0068] The flow rate fluctuation range (Tol) can serve as a standard for the control unit (40) to control the pump. In one embodiment, the control unit (40) can change the initial pump flow rate setting value input to the input unit (30) if the absolute value of the relationship between the measured flow rate and the target flow rate is greater than the flow rate fluctuation range.

[0069] At this time, to calculate the pump flow rate setting value, the control unit (40) may be configured to calculate the pump flow rate setting value based on the following mathematical formula.

[0070] [Mathematical Formula 4]

[0071]

[0072] Here, Q set,new : Pump flow rate set value (ml / min), Q set,old : Q set,new Previously set pump flow rate setting (ml / min), R F : Ratio of actual measured flow rate to target flow rate (F mes / F set ), ω: weight (0 < ω < 1), n: integer greater than or equal to 1, Q0: initial pump flow rate setting

[0073] And, if the absolute value of the relationship between the measured flow rate and the target flow rate is smaller than the flow rate fluctuation range, the control unit (40) can control the pump to maintain the flow rate by calculating the flow rate according to the change in weight of the liquid raw material in the storage unit (40) during the flow rate measurement time.

[0074] That is, the fact that the absolute value of the relationship between the measured flow rate and the target flow rate is greater than the flow rate fluctuation range may mean that the measured flow rate is greater than the target flow rate. Therefore, if the measured flow rate is greater than the target flow rate, the control unit (40) can change the pump flow rate setting value so that the measured flow rate converges to the target flow rate.

[0075] In addition, the relationship regarding the flow rate fluctuation range includes the pump flow rate control precision and the scale measurement precision as variables, so that the flow rate fluctuation range can be automatically set according to the specifications of the pump and the scale. That is, the flow rate automatic control device (100) according to the present invention can automatically control the criteria for controlling the pump according to the specifications of the pump and the scale.

[0077] FIG. 3 is a flowchart illustrating the procedure for controlling the flow rate according to the present invention.

[0078] The automatic flow rate control method includes a step of operating a pump (S100), a step of measuring time and weight (S200), a step of calculating a flow rate (S300), a step of calculating a relationship between the flow rate fluctuation range and the measured flow rate and the target flow rate (S400), and a step of changing input values ​​or controlling the pump (S500).

[0079] The step of operating the pump (S100) is a step of setting an initial input value in the input section and driving the pump according to the input value. At this time, the input value may be a variable for calculating the flow rate fluctuation range (Tol) that serves as a standard for controlling the pump.

[0080] The input value is the target flow rate (F set ), density of liquid raw material (d), pump flow control precision (Res p ), scale measurement precision (Res b ), time interval for measuring the weight of liquid raw materials (t step ) and average flow measurement time range (t avg It may include one or more of the following.

[0081] And, the step of operating the pump (S100) may further include the step of transmitting data regarding the input target flow rate and the density of the liquid raw material to the control unit to calculate an initial pump flow rate setting value.

[0082] Furthermore, the step of operating the pump (S100) may include a step of initializing the measuring unit.

[0084] The step of measuring time and weight (S200) is a step of measuring the cumulative time at which the liquid raw material in the storage unit begins to decrease and the change in weight of the liquid raw material under conditions where the measuring unit corresponds to the input value.

[0085] That is, the step of measuring time and weight (S200) can calculate the accumulated time and weight during the time interval for measuring the weight of the liquid raw material input into the input unit.

[0087] The step of calculating the flow rate (S300) is a step in which the control unit receives data measured by the measurement unit and calculates the flow rate for a set period of time. More specifically, the flow rate measurement cumulative time (△t) and weight change (△m) calculated by the measurement unit are transmitted to the control unit, and the control unit can calculate the flow rate through the flow rate measurement cumulative time (△t) and weight change (△m).

[0089] The step of calculating the relationship between the flow rate fluctuation range and the measured flow rate and the target flow rate (S400) is a step in which the control unit calculates the relationship between the flow rate fluctuation range and the measured flow rate and the target flow rate according to the input value and the flow rate.

[0090] At this time, the flow rate fluctuation range can be calculated based on the input value entered during the pump operation step (S100) as a standard for controlling the pump. Additionally, the flow rate fluctuation range can vary according to the accumulated time measured by the measuring unit.

[0092] The step of changing the input value or controlling the pump (S500) is a step in which the control unit changes the input value or controls the pump according to the absolute value of the relationship between the measured flow rate and the target flow rate and the magnitude of the flow rate fluctuation range.

[0093] More specifically, the step of changing the input value or controlling the pump (S500) may include a step of changing the input value if the absolute value of the relationship between the measured flow rate and the target flow rate in the control unit is greater than the flow rate fluctuation range (S510), and a step of controlling the pump to maintain the flow rate calculated in the control unit if the absolute value of the relationship between the measured flow rate and the target flow rate is smaller than the flow rate fluctuation range (S520).

[0094] Therefore, the initial pump flow rate setting value calculated in the pump operation step (S100) can be set small to allow for a large fluctuation range in the flow rate. That is, the input target flow rate input in the pump operation step (S100) can be set small.

[0095] During the initial stage of flow measurement, the flow rate may not be accurately measured due to pulsation or scale precision, but this effect diminishes over time, and the range of flow rate fluctuation gradually decreases over time from the point at which the input value is changed.

[0096] In other words, the flow fluctuation range can converge to the target value of the flow fluctuation range as time passes.

[0097] By making the range of flow rate fluctuation large at the beginning of the input value change and decreasing it over time, it has the effect of preventing unnecessary changes in input values ​​caused by inaccurate flow rate measurements at the beginning of the input value change.

[0098] At this time, the control unit, within an arbitrary average flow rate measurement time range (t avg ) can be set. During initial operation, pump pulsation and scale measurement precision (Res hBecause the absolute value of the relationship between the measured flow rate and the target flow rate may appear larger than the actual value due to influences such as ), the flow rate fluctuation range is gradually reduced over time according to Equation 1. When the absolute value of the relationship between the measured flow rate and the target flow rate is smaller than the flow rate fluctuation range, the automatic flow rate control device can maintain the pump flow rate setting value until the measurement time range (△t) for calculating the relationship between the measured flow rate and the target flow rate reaches an arbitrarily set average flow rate measurement time range.

[0099] Here, the arbitrary average flow rate measurement time range is from 1 minute to 30 minutes.

[0100] In addition, if the measurement time range (△t) until the relationship between the measured flow rate and the target flow rate is calculated exceeds an arbitrarily set average flow rate measurement time range, the automatic flow rate control device can maintain the flow rate set value by calculating the flow rate during the most recent average flow rate measurement time range.

[0102] Although the present invention has been described with reference to preferred embodiments above, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims. Explanation of the symbols

[0104] 100: Automatic flow control device 10: Storage section 20: Measurement section 30: Input section 40: Control unit

Claims

Claim 1 A storage unit for storing liquid raw materials; a time elapsed for measuring the weight and flow rate of the liquid raw materials stored in the storage unit (△t=t n A measuring unit for measuring -t0); a time interval (t) for measuring the weight of the liquid raw material. step ) and an input unit for inputting an initial pump flow rate setting value; and receiving data from the storage unit, measurement unit, and input unit to input a pump flow rate setting value (Q set,new An automatic flow rate control device comprising: a control unit that generates a pump control signal by changing ); wherein the control unit calculates a relationship between the flow rate fluctuation range, the measured flow rate, and the target flow rate according to the following mathematical formulas 1 and 2. [Mathematical Formula 1] [Mathematical Formula 2] Here, Tol: flow rate fluctuation (gradually decreasing over time), R F : Ratio of actual measured flow rate to target flow rate (F mes / F set ), Res p : Pump flow control precision (ml / min), F set : Target flow rate (g / min), Res b : Balance measurement precision (g), d: Density of liquid raw material (g / ml), α, β, γ: Factors applied to Tol calculation formula (0 < α < 10, 0 < β < 50, 0 < γ < 10), C: Factor applied to Tol calculation formula (0 <C<1000), t n : Flow rate measurement time, where n is an integer greater than or equal to 1 Claim 2 An automatic flow rate control device according to claim 1, wherein the control unit calculates the flow rate according to the change in weight of the liquid raw material during the flow rate measurement time. [Equation 3] Here, F mes : Measured flow rate (g / min), △t: Flow rate measurement time range (cumulative flow rate measurement time, t n -t0, where n is an integer greater than or equal to 1) △m: change in scale weight during △t((t n Balance value at time, m n )-(scale value at time t0, m0)) Claim 3 An automatic flow rate control device according to claim 1, wherein the control unit changes the pump flow rate setting value when the mathematical formula 2 is greater than the flow rate fluctuation range. Claim 4 An automatic flow rate control device according to claim 3, wherein the control unit changes the pump control signal by changing the pump flow rate setting value according to the following mathematical formula 4. [Mathematical Formula 4] Here, Q set,new : Pump flow rate set value (ml / min), Q set,old : Q set,new Previously set pump flow rate setting (ml / min), R F : Ratio of actual measured flow rate to target flow rate (F mes / F set ), ω: weight (0 < ω < 1), n: integer greater than or equal to 1 Claim 5 An automatic flow rate control device according to claim 1, wherein the control unit controls the pump to maintain the flow rate by calculating the flow rate according to the weight change of the storage unit during the flow rate measurement time when the mathematical formula 2 is smaller than the flow rate fluctuation range. Claim 6 The method comprises: a step of setting an initial input value in an input unit and operating a pump according to said input value; a step in which a measuring unit measures the cumulative time at which the liquid raw material in the storage unit begins to decrease and the weight of said liquid raw material under conditions corresponding to said input value; a step in which a control unit receives data measured by said measuring unit and calculates a flow rate through the ratio of the weight change of said liquid raw material during said cumulative time; a step in which the control unit calculates a flow rate fluctuation range and a relationship between the measured flow rate and the target flow rate according to said input value and said flow rate; and a step in which the control unit changes said input value or controls said pump according to the absolute value of the relationship between the measured flow rate and the target flow rate and the magnitude of said flow rate fluctuation range; wherein the step of changing said input value or controlling said pump includes a step in which the control unit changes said input value if the absolute value of the relationship between said measured flow rate and the target flow rate is greater than said flow rate fluctuation range. and a step of controlling the pump to maintain the flow rate calculated by the control unit when the absolute value of the relationship between the measured flow rate and the target flow rate is smaller than the flow rate fluctuation range; wherein the flow rate fluctuation range and the relationship between the measured flow rate and the target flow rate are calculated according to the following mathematical formulas 1 and 2. [Mathematical Formula 1] [Mathematical Formula 2] Here, Tol: flow rate fluctuation (gradually decreasing over time), R F : Ratio of actual measured flow rate to target flow rate (F mes / F set ), Res p : Pump flow control precision (ml / min), F set : Target flow rate (g / min), Res b : Balance measurement precision (g), d: Density of liquid raw material (g / ml), α, β, γ: Factors applied to Tol calculation formula (0 < α < 10, 0 < β < 50, 0 < γ < 10), C: Factor applied to Tol calculation formula (0 <C<1000), t n : Flow rate measurement time, where n is an integer greater than or equal to 1 Claim 7 A method for automatic flow rate control according to claim 6, wherein the initial input value comprises one or more of the following: an input target flow rate, a density of the liquid raw material, a pump flow rate control precision, a scale measurement precision, a time interval for measuring the weight of the liquid raw material, and a time range for measuring the average flow rate. Claim 8 delete Claim 9 In claim 6, the step of controlling the pump comprises an average flow rate measurement time range (t) in which the measurement time range (△t) until the relationship between the measured flow rate and the target flow rate is calculated is arbitrarily set. avg A method for automatic flow rate control characterized by maintaining a pump flow rate set value until reaching ). Claim 10 A method for automatic flow rate control according to claim 9, characterized in that the average flow rate measurement time range is 1 minute to 30 minutes.

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