JP2012063362A - Method of controlling quantitative discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform control to make a discharge amount of liquid constant with high precision, and to prevent discharge precision from decreasing by detecting a case in which air is mixed with the liquid.SOLUTION: A discharge device 10 has first and second passages 12, 16 in which the liquid circulates. A pair of detection parts 20a, 20b capable of detecting the pressure of the liquid in the first and second passages 12, 16 is provided below the first and second passages 12, 16, and air vent passages 48a, 48b capable of discharging air included in the liquid are provided above the first and second passages 12, 16, respectively. Then a flow rate control part 22 which reduces the flow rate of the liquid is provided between a first housing 14 and a second housing 18 so as to face the first and second passages 12, 16 .

Description

  The present invention relates to a control method for a fixed-quantity discharge device that can always discharge a predetermined amount of fluid.

  2. Description of the Related Art Conventionally, liquid ejecting apparatuses for supplying chemicals, paints, cleaning liquids, and the like have been employed in semiconductor manufacturing apparatuses, coating apparatuses, medical equipment, and the like.

  Such a liquid discharge device includes, for example, a filling liquid tank filled with a filling liquid, and a filling nozzle connected to the filling liquid tank via a pipe and discharging the filling liquid to the outside. Between the liquid tank and the filling nozzle, a flow meter for measuring the flow rate of the filling liquid and a stop valve for switching a supply state of the filling liquid to the nozzle are connected via a pipe. Then, when the filling liquid is supplied from the filling liquid tank toward the filling nozzle, the flow rate is measured by the flow meter, the filling liquid is discharged from the filling nozzle, and the flow rate is preset in the control device. When the value is reached, a signal is output from the control device to the stop valve, and the stop valve is closed to block the flow of the filling liquid flowing through the pipe (for example, see Patent Document 1).

JP 2001-39430 A

  By the way, in the prior art which concerns on patent document 1, it is set as the structure which performs discharge control of a filling liquid under the opening-and-closing action of a stop valve, However, The said stop valve begins to open and close by the signal from a control apparatus, and actually piping A time lag (delay) occurs until the communication state is completely switched. In other words, the stop valve requires a predetermined time from when a signal is input until it actually starts to open and close.

  Therefore, for example, when the flow rate measured by the flow meter reaches a preset discharge amount from the filling nozzle, the signal from the control device starts the valve closing until the valve is completely closed. In the meantime, a predetermined amount of filling liquid is discharged. As a result, a variation occurs between a preset discharge amount from the filling nozzle and an actual discharge amount, and it is difficult to control the discharge amount with high accuracy.

  Further, in such a liquid discharge device, air may be mixed into the filling liquid for some reason, and the air is discharged when the discharge amount (flow rate) of the filling liquid containing the air is measured with a flow meter. There is a problem that an error occurs due to the influence of the above, and the discharge amount cannot be measured accurately, resulting in a decrease in measurement accuracy.

  The present invention has been made in consideration of the above-described problems, and can control the discharge amount of the liquid with high accuracy and can detect the mixing of air into the liquid to detect the discharge amount. It is an object of the present invention to provide a method for controlling a quantitative discharge device capable of maintaining the above.

In order to achieve the above object, the present invention outputs a valve opening command to the flow rate control valve, and circulates the liquid in the passage.
A first pressure and a second pressure of the liquid on the upstream side and the downstream side of the flow rate adjustment unit are detected through a pair of detection units arranged along the passage, respectively, and the first pressure and the second pressure are detected. Integrating the flow rate of the liquid based on the pressure difference from the pressure to calculate the discharge amount; and
When the differential pressure is in a steady state where the pressure is maintained constant and the differential pressure reaches a preset steady pressure, the steady pressure is set under the valve opening action after the valve opening command is output. A step of calculating a correction amount based on a rising characteristic of the differential pressure until it reaches,
A target value obtained by subtracting the correction amount from a preset set discharge amount is compared with the discharge amount, and when the discharge amount reaches the target value, a valve closing command is output to the flow control valve. Process,
Calculating a discharge amount from when the valve closing command is output until the flow control valve is closed;
It is characterized by having.

  According to the present invention, after the valve opening command is output to the flow control valve, the discharge amount is integrated from the differential pressure based on the first and second pressures detected by the detector, and the differential pressure increases. When it is confirmed that the set steady pressure is maintained and the steady pressure is maintained constant, the correction amount is calculated based on the rising characteristics of the differential pressure.

  When the accumulated discharge amount reaches a target value obtained by subtracting the correction amount from the preset set discharge amount, a valve closing command is output to the flow control valve to start the valve closing operation. At the same time, the amount of discharge from when the valve closing command is output until the valve closing is completed is calculated.

  Therefore, a correction amount is set in consideration of an operation delay from the valve closing command to the completion of valve closing in the flow control valve, and the valve closing command is output to the flow control valve early based on the correction amount. By controlling as described above, since the operation time of the flow control valve is taken into account, it is possible to control the quantitative discharge device with high accuracy without being affected by the operation delay (time lag) of the flow control valve, A preset discharge amount set in advance can be obtained.

  In addition, by calculating the correction amount when measuring the discharge amount next time based on the discharge amount discharged from the valve closing command until the valve closing is completed, and correcting the timing of outputting the valve closing command, Furthermore, it becomes possible to control the discharge amount with high accuracy.

A step of detecting pressure changes in the second pressure and the differential pressure, respectively, and detecting mixing of air into the liquid;
It is good to have the process of specifying the site | part in which the said air exists in the said channel | path according to the said pressure change.

  Thereby, it can be confirmed that air is mixed in the liquid based on the pressure change of the second pressure and the differential pressure, and the location of the air in the passage can be specified. It is possible to warn of the air contamination and the contamination site, and to deal with it quickly and reliably. For this reason, it is possible to prevent a decrease in detection accuracy of the discharge amount due to air mixing.

Furthermore, between the current first pressure and the differential pressure detected by the detection unit with respect to the first pressure and the differential pressure when the liquid stored in advance normally flows in the passage. Detecting the pressure change that occurs in
It is good to have the process of specifying the part in which the abnormal pressure of the liquid has arisen in the channel based on the pressure change.

  Thereby, the pressure change of the first pressure and the differential pressure detected by the detection unit can be detected, the pressure abnormality in the passage can be confirmed based on the detection result, and the occurrence site of the pressure abnormality in the passage can be determined. Since it can be identified, for example, even when clogging, leakage, etc. occur in the pipe, it can be quickly detected and dealt with. Therefore, by eliminating the pressure abnormality in the quantitative discharge device, it is possible to prevent variation when the liquid discharge amount is measured, and to detect the discharge amount with high accuracy.

  According to the present invention, the following effects can be obtained.

  That is, a correction amount is set in consideration of an operation delay from the valve closing command to the valve closing in the flow control valve, and the valve closing command is output to the flow control valve early based on the correction amount. And the discharge amount discharged from the valve closing command to the valve closing is calculated, so that the discharge amount can be controlled in the quantitative discharge device without being affected by the operation delay of the flow control valve. In addition to being able to perform with high accuracy, by setting the correction amount based on the discharge amount after the valve closing command, it is possible to perform control with higher accuracy.

It is a whole longitudinal cross-sectional view of the fixed amount discharge apparatus which concerns on embodiment of this invention. It is a schematic block diagram of the fixed quantity discharge system containing the fixed quantity discharge apparatus of FIG. It is a longitudinal cross-sectional view which shows the case where a sealing plug is removed from the fixed discharge apparatus of FIG. 1, and the air in a liquid is discharged | emitted outside. It is a flowchart which shows the content which performs the discharge amount control of the liquid with the fixed_quantity | quantitative_discharge apparatus of FIG. It is a characteristic curve figure which shows the relationship between the pressure of the liquid discharged from a fixed discharge apparatus, and time. It is a characteristic curve figure which shows the relationship between the discharge amount of the liquid from a fixed amount discharge apparatus, the opening / closing operation | movement of an on-off valve, and the valve opening / closing command from a control part. FIG. 7A to FIG. 7D are characteristic diagrams showing the relationship between the valve opening / closing command to the on-off valve, the pressure, and the differential pressure when clogging or the like occurs in the quantitative discharge system.

  A preferred embodiment of a method for controlling a quantitative discharge device according to the present invention will be described in detail below with reference to the accompanying drawings.

  In FIG. 1, reference numeral 10 indicates a quantitative discharge device to which the quantitative discharge control method according to the embodiment of the present invention is applied.

  As shown in FIG. 1, the quantitative discharge device 10 is disposed adjacent to the first housing 14 having a first passage (passage) 12 into which a liquid (for example, pure water) is introduced, and the first housing 14. And a second housing 18 having a second passage (passage) 16 communicating with the first passage 12, and a set for detecting the pressure of the liquid provided in the first and second housings 14 and 18, respectively. Detection units 20a and 20b, a flow rate adjustment unit 22 provided between the first passage 12 and the second passage 16 and capable of adjusting the flow rate of the liquid to a predetermined amount, and the first and second passages 12. , 16 a set of sealing plugs (sealing members) 26a, 26b for closing the openings 24a, 24b communicating with the 16 and a set of joints 28a connected to the first and second passages 12, 16 respectively. 28b. In addition, since the 1st housing 14 and the 2nd housing 18 are substantially the same shape, in the following description, the detailed description about the said 1st housing 14 is given, and the detailed description about the 2nd housing 18 is abbreviate | omitted. To do.

  The first housing 14 is disposed on the upstream side where the liquid is introduced into the inside through one joint 28a, and is formed in the first passage 12 penetrating in a substantially horizontal direction and the lower portion of the first passage 12. A mounting hole 30a in which one detection unit 20a is mounted and an opening 24a formed in the upper part of the first passage 12 and sealed by one sealing plug 26a.

  The first passage 12 has a main pipe portion 32 extending with substantially the same diameter, a first port 34 formed on one end side of the main pipe portion 32 to which a joint 28a is connected, and the other end portion of the main pipe portion 32. The first taper portion (inclined portion) 36 is formed on the side and gradually decreases in diameter in a direction away from the first port 34. The joint 28a is screwed into the first port 34 via a screw engraved along the inner peripheral surface, and the joint 28a is supplied with liquid by a first pipe 38a as shown in FIG. It is connected to a filled tank 40. And as FIG. 1 shows, the liquid in the tank 40 is supplied to the 1st channel | path 12 through the 1st piping 38a and the coupling 28a.

  2, the quantitative discharge system including the tank 40 described above, the quantitative discharge device 10, the first pipe 38a connecting the quantitative discharge device 10 and the tank 40, and the quantitative discharge device 10 are provided. And an on-off valve (flow rate control valve) 72 (described later) connected via a second pipe 38b, and a control unit 70 connected to each of the detection units 20a and 20b of the quantitative discharge device 10.

  The mounting hole 30 a is formed so as to open to the lower surface side of the first housing 14, and communicates with the first passage 12 through the first communication passage 42. The first communication path 42 is formed with a diameter smaller than the inner peripheral diameter of the mounting hole 30a, and the first communication path 42 is a taper that gradually increases in diameter from the first communication path 42 toward the mounting hole 30a. It communicates with the mounting hole 30a through the hole 44. That is, when air enters the mounting hole 30a, the air moves toward the first communication path 42 along the inclined wall surface of the tapered hole 44 provided above the mounting hole 30a. It can be discharged from the mounting hole 30a through the single communication passage 42. This prevents air from staying in the mounting hole 30a.

  Further, a screw is engraved along the peripheral surface of the lower end portion of the mounting hole 30a, and after the detecting portion 20a is inserted into the mounting hole 30a, one holding plug 46a is screwed. Thereby, the detection part 20a is hold | maintained with respect to the mounting hole 30a.

  The opening 24a has substantially the same diameter, and a sealing plug 26a is screwed through a screw engraved on the inner peripheral surface thereof. Therefore, communication with the outside of the opening 24a is blocked by the sealing plug 26a, and the airtightness in the opening 24a is maintained. A space S having a predetermined capacity is formed between the lower surface of the sealing plug 26a and the bottom wall surface of the opening 24a.

  Further, an air vent passage (discharge passage) 48a extending toward the first passage 12 is connected to the opening 24a, and the opening 24a and the first passage 12 communicate with each other through the air vent passage 48a. is doing. Specifically, the air vent passage 48 a is connected substantially orthogonal to the boundary portion between the main pipe portion 32 and the first taper portion 36 in the first passage 12. That is, since the air contained in the liquid moves upward in the liquid and collects on the upper surface side in the first passage 12, the air moves along the inner peripheral surface of the main pipe portion 32, Before reaching the first taper portion 36, the air is guided to an air vent passage 48 a extending upward.

  On the other hand, the air existing in the vicinity of the first taper portion 36 gradually moves toward the main pipe portion 32 along the inner peripheral surface whose diameter is increased toward the main pipe portion 32, and is guided to the air vent passage 48a. . Then, air is introduced into the space S of the opening 24a through the air vent passage 48a.

  The first housing 14 is formed with a convex portion 50 projecting a predetermined length on the side surface facing the second housing 18, and the first passage 12 is opened at a substantially central portion of the convex portion 50. A seal member 52a is attached to the convex portion 50 on the side surface facing the second housing 18 via an annular groove, and the seal member 52a comes into contact with a plate 74 (described later) of the flow rate adjustment unit 22, Airtightness between the first housing 14 and the flow rate adjusting unit 22 is maintained.

  The second housing 18 is disposed on the downstream side to which the liquid is supplied through the first housing 14, and a concave portion 54 that is recessed by a predetermined depth is formed on a side surface that becomes the first housing 14 side. Then, by inserting the convex portion 50 of the first housing 14 into the concave portion 54, the second housing 18 is connected in a state of being positioned with respect to the first housing 14. At this time, the flow rate adjusting unit 22 is sandwiched between the concave portion 54 and the convex portion 50, and the seal member 52 b attached to the end surface of the concave portion 54 comes into contact with the plate 74, whereby the second housing 18. And the air flow rate adjusting unit 22 are reliably maintained.

  Further, the second housing 18 has a second passage 16 penetrating in a substantially horizontal direction, a mounting hole 30b formed in a lower portion of the second passage 16 in which the detection unit 20b is mounted, and the second passage 16. And an opening 24b formed at the top and sealed by the sealing plug 26b. The second passage 16 is formed so as to be in line with the first passage 12 of the first housing 14.

  The second passage 16 includes a main pipe portion 56 extending with substantially the same diameter, a second port 58 formed on one end side of the main pipe portion 56 to which the other joint 28b is connected, and the other of the main pipe portion 56. A second taper portion (inclined portion) 60 formed on the end side and gradually reducing in diameter in a direction away from the second port 58. A joint 28b is screwed into the second port 58. And the liquid in the 2nd channel | path 16 is guide | induced to the 2nd piping 38b (refer FIG. 2) through the coupling 28b. In addition, the length, diameter, etc. of the 2nd channel | path 16 are set so that it may become substantially the same shape as the 1st channel | path 12. FIG.

  Further, when the second housing 18 is connected to the first housing 14, the second taper portion 60 and the first taper portion 36 opened in the recess 54 are adjacent to each other.

  The mounting hole 30b is formed on the lower surface side of the second housing 18, communicates with the second passage 16 through the second communication passage 62, and the detection portion 20b is inserted therein and held by the other holding plug 46b.

  The other sealing plug 26b is screwed into the opening 24b, and the opening 24b is closed to keep the opening 24b airtight. Further, an air vent passage (discharge passage) 48b communicating with the second passage 16 is connected to the opening 24b. The air vent passage 48b is connected substantially perpendicularly to the boundary portion between the main pipe portion 56 and the second taper portion 60 in the second passage 16, so that the air contained in the liquid is upward in the liquid. By moving and moving along the second taper portion 60, when the second taper portion 60 reaches the main pipe portion 56, it is guided to the air vent passage 48 b that extends upward. On the other hand, the air existing in the vicinity of the second taper portion 60 gradually moves toward the main pipe portion 56 along the inner peripheral surface whose diameter increases toward the main pipe portion 56 side, and is guided to the air vent passage 48b. .

  The detection units 20a and 20b are composed of a pressure sensor capable of detecting the pressure of the liquid flowing through the first and second passages 12 and 16, and a body 64 having a substantially U-shaped cross section, and an inside of the body 64 A sensor main body 66 disposed and opposed to the first communication path 42, and a seal ring 68 attached to an end surface of the body 64 are included. When the body 64 is mounted in the mounting holes 30a and 30b, the seal ring 68 comes into contact with the inner wall surfaces of the mounting holes 30a and 30b, so that liquid is generated between the body 64 and the mounting holes 30a and 30b. Is prevented from leaking.

  Since the sensor body 66 is disposed at a position facing the first and second communication passages 42 and 62 via the first and second communication passages 42 and 62 and the tapered hole 44, the first and second communication passages 42 and 62 are disposed. Pressures P1 and P2 of the liquid introduced into the mounting holes 30a and 30b from the first and second passages 12 and 16 through the communication passages 42 and 62 are detected. As shown in FIG. 2, the detection units 20a and 20b are respectively connected to the control unit 70 via wiring, and the pressures P1 and P2 detected by the detection units 20a and 20b are respectively detected as detection signals. Is output to the unit 70.

  On the other hand, on the downstream side of the second housing 18, an on-off valve 72 is connected via a joint 28 b and a second pipe 38 b connected to the joint 28 b, and the on-off valve 72 is opened and closed by a control signal from the control unit 70. Operate. The on-off valve 72 is, for example, an electromagnetic control type that can open and close the valve body by exciting a solenoid under an energization action of current and can switch the flow state of the liquid flowing through the second pipe 38b. . The third pipe 38 c is connected to the downstream side of the on-off valve 72, and the communication state with the second pipe 38 b is switched under the opening / closing action of the on-off valve 72.

  As shown in FIG. 1, the flow rate adjusting unit 22 includes an orifice hole 76 formed in a plate 74 sandwiched between the first housing 14 and the second housing 18, and the orifice hole 76 is a first passage. 12 and the second passage 16. The orifice hole 76 is formed to have a smaller diameter than the diameters of the first and second passages 12 and 16 and is formed coaxially with the first and second passages 12 and 16. That is, the liquid flowing from the first passage 12 to the second passage 16 passes through the orifice hole 76, so that the flow rate is reduced by a predetermined amount and flows to the second passage 16.

  The quantitative discharge device 10 according to the embodiment of the present invention is basically configured as described above. Next, its operation and effect will be described in relation to the quantitative discharge control method.

  In such a fixed amount discharge device 10, generally, when a liquid is circulated through the fixed amount discharge device 10 for the first time, air is introduced together with the liquid at the start of the flow, and the air is mixed into the liquid. there is a possibility. In this way, there is a concern that the liquid mixed with air cannot accurately detect the flow rate of the liquid.

  Therefore, first, a method for removing air mixed in the liquid in the quantitative discharge device 10 will be described.

  First, as shown in FIG. 1, the tanks in the first and second passages 12 and 16 are opened with the openings 24a and 24b of the first and second housings 14 and 18 closed by the sealing plugs 26a and 26b. Liquid is supplied from 40. In this case, the operation is performed in a state where the end of the second pipe 38b is closed and the flow of the liquid is blocked. Then, the air mixed in the liquid in the first and second passages 12 and 16 and the first pipe 38a moves upward due to the specific gravity difference with the liquid, and the air in the first and second passages 12 and 16 flows. Collected upward, moved along the inner peripheral surfaces of the first and second passages 12 and 16, and led to air vent passages 48a and 48b extending upward, respectively.

  Further, in the vicinity of the flow rate adjusting portion 22, the first and second tapered portions 36 and 60 that gradually increase in diameter in a direction away from the orifice hole 76 are adjacent to each other. Air is guided along the inner peripheral surfaces of the first and second tapered portions 36, 60 to the air vent passages 48a, 48b.

  The air accumulates in the space S between the openings 24a and 24b and the sealing plugs 26a and 26b through the air vent passages 48a and 48b. A part of the liquid also flows into the space S through the air vent passages 48a and 48b.

  Next, as shown in FIG. 3, the sealing plugs 26a and 26b are screwed to be removed from the openings 24a and 24b, respectively, so that the openings 24a and 24b communicate with the outside. The air introduced into the openings 24a and 24b from the first and second passages 12 and 16 is discharged to the outside through the openings 24a and 24b. Thereby, the air mixed in the liquid in the fixed discharge device 10 is reliably and suitably removed.

  Finally, in a state where the openings 24a and 24b are filled with liquid, the openings 24a and 24b are screwed again by screwing the sealing plugs 26a and 26b so that air does not enter the openings 24a and 24b. The optimum use condition of the fixed quantity discharge device 10 which is closed again and in which air is not mixed into the liquid is obtained.

  Next, the operation and effect of the fixed-quantity ejection device 10 that has been evacuated from the liquid will be described. The on-off valve 72 (see FIG. 2) is in a closed state, and the case where the discharge of the liquid from the quantitative discharge device 10 is stopped is defined as an initial state.

  First, based on the flowchart of FIG. 4, in step S1, a control signal serving as a valve opening command is output from the control unit 70 to the on-off valve 72, and the on-off valve 72 is opened from the above-described initial state. As a result, the flow of the liquid blocked by the on-off valve 72 is released, and the liquid flows through the first pipe 38a, the first and second passages 12 and 16, and passes through the second and third pipes 38b and 38c. It becomes a state where discharge is possible.

  Next, in step S2, the pressure P1 of the liquid in the first passage 12 is detected by one detection unit 20a, and the pressure P2 of the liquid in the second passage 16 is detected by the other detection unit 20b. P1 and P2 are output as detection signals to the control unit 70 (see FIG. 2). Accordingly, the flow rate (discharge amount) of the liquid flowing through the first and second passages 12 and 16 is calculated based on the differential pressure ΔP between the pressure P1 and the pressure P2, and the discharge amount is obtained by integrating the flow rate. Qa is calculated.

  Then, as shown in FIG. 5, it is determined in step S <b> 3 whether or not the differential pressure ΔP has risen and has reached a steady pressure Pc preset in the control unit 70.

  For example, immediately after the valve opening command is output to the on-off valve 72, the pressure difference ΔP between the pressure P1 of the first passage 12 and the pressure P2 of the second passage 16 changes so as to gradually increase from zero. In this case, since a predetermined time is required until the steady pressure Pc is reached, in this case, in step S3, the steady pressure Pc is not reached, and the process proceeds to step S4.

  Next, in step S4, it is determined whether or not the pressure ΔP is a steady pressure Pc and is a pressure steady state maintained substantially constant, and the above determination is repeated until the liquid pressure reaches a steady state. Done. Specifically, when the pressure steady state has not been reached, the process proceeds to step S5, and the operation from when the valve opening command is output to the on-off valve 72 until the on-off valve 72 is actually completely opened. The time T1 is compared with the valve opening setting time Tst preset in the control unit 70. When the valve opening set time Tst and the operation time T1 are different (T1 ≠ Tst), air is mixed in the liquid in the second pipe 38b or the pressure in the second pipe 38b is increased. Since there is a possibility that an abnormality has occurred, in step S6, a warning of air mixing into the second pipe 38b or pressure abnormality is output to a display unit (not shown).

  When air (for example, air bubbles) is mixed in the liquid in the second pipe 38b, the time required for the pressure P2 and the differential pressure ΔP to rise and the time required for the fall become longer than normal. Therefore, it is confirmed that the air exists in the second pipe 38b.

  On the other hand, when the operation time T1 is substantially equal to the valve opening set time Tst (T1≈Tst), the calculation of the discharge amount Qa based on the integration of the flow rate is repeatedly performed until the steady pressure Pc is reached again in step S2. .

  In general, in such a quantitative discharge device 10, as shown in FIG. 6, after the valve closing command is output from the control unit 70 to the on-off valve 72, the on-off valve 72 is actually operated to operate the valve. Since there is a delay until the closed state is reached, the liquid is ejected more than a predetermined desired amount. In other words, the on-off valve 72 requires a predetermined time until the valve closing operation is completely completed after the control signal (valve closing command) for performing the valve closing operation is input. Therefore, it is necessary to perform correction by estimating the discharge amount discharged with the delay of the valve opening operation in the on-off valve 72.

  Next, when the steady pressure state is confirmed in step S4, the correction amount K is calculated based on the discharge amount Qa (see FIG. 5) in which the flow rate is integrated until the steady pressure state is reached in step S7. Done.

  As shown in FIG. 5, when the liquid is first circulated through the quantitative discharge device 10, the correction amount K is such that the rising characteristic region Va of the differential pressure ΔP when the valve is opened is a valve closing command to the on-off valve 72. It is estimated and set (K = Va≈Vb) to be approximately equal to the discharge amount Vb of the liquid discharged from the input until the valve is completely closed (Va≈Vb). The rising characteristic region Va of the differential pressure ΔP when the valve is opened is based on a value obtained by multiplying a value obtained by multiplying the flow rate Qc when the pressure is in a steady state and the time T required to reach the pressure steady state. It is calculated by subtracting the accumulated discharge amount Qa until the steady state is reached (Va = Qc × T−Qa).

  Further, the correction amount K for the second and subsequent times when the liquid is circulated through the constant rate discharge device 10 is the characteristic value Va ′ up to the previous time stored in the control unit 70 and the valve closing command until the valve is closed. This is calculated by multiplying the ratio of the liquid discharge amount Vb ′ to the current rising characteristic region Va (K = Va × Vb ′ / Va ′). The rising characteristic region Va ′ and the discharge amount Vb ′ are calculated using the average values of the past several times.

  Then, after the detection of the steady pressure Pc is confirmed in step S8, it is determined in step S9 whether or not the steady pressure Pc is abnormal with respect to the set pressure. The set pressure is set in the control unit 70 in advance. If the steady pressure Pc is found to be abnormal compared to the set pressure, the pressure abnormality is output to a display unit (not shown) in step S10, and the steady pressure Pc is substantially equal to the set pressure and is normal. If it is determined, the flow returns to step S2 again to integrate the liquid flow rate, and the discharge amount Qa is repeatedly calculated.

  On the other hand, when the detection of the steady pressure Pc is completed in step S3, it is determined in step S11 whether or not a control signal serving as a valve closing command is output from the control unit 70 to the on-off valve 72. If it is determined that it is not yet time to output the valve closing command, the process proceeds to step S12, and the discharge amount Qa that is actually discharged and accumulated, and the discharge amount set in advance in the control unit 70 are set. A comparison is made with a target value Qs (Qs = Qb−K) obtained by subtracting the correction amount K from Qb (see FIG. 6), and it is determined whether or not the discharge amount Qa is larger than the target value Qs. When the accumulated discharge amount Qa exceeds the target value Qs (Qa> Qs), in step S13, a control signal serving as a valve closing command is output to the on-off valve 72, and the on-off valve 72 is Start the valve closing operation. Then, the flow returns to step S2, and the flow rate is integrated until the on-off valve 72 is completely closed and the flow rate of the liquid flowing through the first and second passages 12 and 16 becomes 0, and the discharge amount Qa. Is continuously repeated.

  If the discharge amount Qa has not yet reached the target value Qs (Qa <Qs), it is determined in step S14 whether or not the steady pressure Pc is abnormal with respect to the preset pressure, and the steady pressure Pc is determined. Is different from the set pressure, the passage of air mixed in the liquid in the flow rate adjusting unit 22 or the discharge of the air is output as a warning to a display unit (not shown) and displayed (step S15).

  When air (for example, air bubbles) mixed in the liquid passes through the flow rate adjusting unit 22, the steady pressure Pc set in advance or a sudden rise in pressure P2 with respect to the steady pressure detected in the past. Alternatively, since the pressure difference ΔP is reduced, it is confirmed that the air has passed through the flow rate adjusting unit 22.

  When the steady pressure Pc is substantially equal to the set pressure and is normal, the process returns from step S14 to step S2 again, and the liquid discharge amount Qa is continuously calculated.

  Then, after the opening / closing valve 72 starts the valve closing operation based on the valve closing command, it is confirmed in step S16 whether the opening / closing valve 72 is actually closed. If the on-off valve 72 has not yet been closed, the process returns to step S2 until the valve is completely closed, the discharge amount Qa is repeatedly calculated, and if the valve is confirmed to be closed, step S2 is performed. The process proceeds to S17, and the discharge amount Qa from the valve closing command to the actual valve closing is stored in the control unit 70 (step S17).

  Finally, in step S18, the operation time T2 from the valve closing command from the control unit 70 until the on-off valve 72 is actually closed is compared with the valve closing set time Tsp preset in the control unit 70, If the difference is less than or exceeding the valve closing set time Tsp, air may be mixed into the liquid in the second pipe 38b, or a pressure abnormality in the second pipe 38b may be considered. In S19, air contamination into the liquid or abnormal pressure of the liquid is displayed as a warning, and the current process in the flowchart shown in FIG. 4 is terminated.

  On the other hand, when the operation time T2 is substantially equal to the valve closing set time Tsp (T2≈Tsp), the current process in the flowchart shown in FIG.

  In addition, when air (for example, bubbles) is mixed in the liquid in the third pipe 38c, the pressure P2 is decreased with respect to a preset steady pressure Pc or a steady pressure detected in the past, or Since the differential pressure ΔP increases, it is confirmed that air exists in the third pipe 38c.

  Then, when the discharge amount is controlled next time in the quantitative discharge device 10, as shown in FIG. 6, the valve from the control unit 70 for the on-off valve 72 is based on the correction amount K calculated in this way. When the closing command reaches the target value Qs obtained by subtracting the correction amount K from the preset discharge amount setting value Qb, the valve closing command is output to the on-off valve 72. That is, the valve closing operation is started by a predetermined time E earlier than the original timing D when the opening / closing valve 72 is closed, and the operation of the opening / closing valve 72 is controlled by taking the operation time of the opening / closing valve 72 into account. A desired discharge amount (set value Qb) set in advance in the quantitative discharge device 10 can be obtained with high accuracy without being affected by a delay (time lag).

  Next, a case will be described in which occurrence of clogging, leakage, or the like is detected based on pressure changes in the first to third pipes 38a to 38c and the quantitative discharge device 10 in the quantitative discharge system. 7A to 7D show valve opening / closing commands output from the control unit 70 to the on-off valve 72, pressures P1 and P2 detected by the detection units 20a and 20b, and a difference calculated by the control unit 70. It is the characteristic view which showed the relationship with the pressure (DELTA) P.

  First, FIG. 7A shows that there is no clogging or the like in the first to third pipes 38 a to 38 c and the fixed amount discharge device 10, and the liquid is supplied from the first pipe 38 a to the second and third pipes 38 b through the fixed amount discharge device 10. It is a characteristic view which shows the case where it distribute | circulates normally to 38c. In this case, the pressure P1 in the first passage 12 is maintained substantially constant regardless of the valve opening / closing command, and the pressure P2 in the second passage 16 is increased or decreased according to the valve opening / closing command. It is understood that Specifically, when the valve is opened, the pressure P2 is decreased and the differential pressure ΔP is increased. Conversely, when the valve is closed, the pressure P2 is increased and the differential pressure ΔP is decreased.

  Next, FIG. 7B shows characteristics when clogging or leakage occurs in the flow rate adjusting unit 22, and the flow rate adjusting unit 22 can detect one pressure in the first passage 12. The pressure P1 detected by the detection unit 20a is maintained substantially constant as in FIG. 7A. On the other hand, in the second passage 16 on the downstream side of the flow rate adjusting unit 22, the pressure P2 decreases and becomes substantially constant from the point H at which clogging or leakage occurs, and the differential pressure ΔP increases accordingly. It is understood that it is almost constant without changing.

  In this way, when the valve P is opened, the pressure P2 remains decreasing, and the differential pressure ΔP continues to increase, so that the flow rate adjusting unit 22 is clogged or leaked. Can be confirmed.

  Next, FIG. 7C shows characteristics when clogging occurs in the second passage 16, the second and third pipes 38 b and 38 c on the downstream side of the flow rate adjusting unit 22, and the second and third Since the pipes 38b and 38c are on the downstream side of the first passage 12 provided with the one detection unit 20a, the pressure P1 in the first passage 12 is maintained substantially constant as in FIG. It can be understood that the internal pressure P2 increases from the point H at which clogging occurs and becomes substantially constant, and at the same time is substantially constant when the differential pressure ΔP decreases.

  As described above, when the valve P is closed, the pressure P2 continues to increase and when the differential pressure ΔP continues to decrease, the second passage 16 on the downstream side of the flow rate adjustment unit 22 is maintained. It is confirmed that clogging has occurred in at least one of the second and third pipes 38b and 38c.

  On the other hand, when liquid leaks from the second passage 16, the second and third pipes 38b, 38c, the pressure P2 in the second passage 16 decreases and the differential pressure ΔP increases. Liquid leakage can be confirmed.

  Finally, FIG. 7D shows the characteristics when clogging or leakage occurs in the first pipe 38a and the first passage 12 on the upstream side of the flow rate adjusting unit 22, and the first point from the point H at which clogging or leakage occurs. It is understood that the pressure P1 in the first passage 12 decreases and becomes substantially constant, and accordingly, the pressure P2 and the differential pressure ΔP in the second passage 16 also decrease and become substantially constant. The

  As described above, when all of the pressures P1, P2 and the differential pressure ΔP are kept lowered even when the valve is closed, the first passage 12 and the first pipe on the upstream side of the flow rate adjusting unit 22 are used. It is confirmed that clogging or leakage occurs in at least one of the 38a.

  That is, by detecting pressure changes of the pressures P1 and P2 and the differential pressure ΔP detected by a pair of detection units 20a and 20b in the quantitative discharge device 10, the quantitative discharge is compared with the pressure change of the liquid at normal time. It is possible to quickly and surely check the clogging, leakage, etc. that have occurred in the flow rate adjusting unit 22, the first to third pipes 38a to 38c, and the first and second passages 12 and 16 of the apparatus 10. For this reason, for example, a warning is displayed by displaying a portion where clogging, leakage, etc. are occurring on a display unit (not shown), and the variation in measuring the liquid discharge amount by eliminating the clogging is detected. This makes it possible to detect the discharge amount with high accuracy.

  As described above, in the present embodiment, the first and second housings 14 and 18 are provided with the air vent passages 48a and 48b that communicate with the first and second passages 12 and 16 and extend upward. By introducing the air mixed in the air into the air vent passages 48a and 48b, the air can be guided to the outside through the openings 24a and 24b from which the sealing plugs 26a and 26b have been removed. The air mixed into the liquid can be reliably and suitably discharged, and the deterioration of the discharge accuracy of the liquid caused by the mixing of the air into the liquid can be prevented.

  In addition, the pair of detection units 20a and 20b is included in the liquid by disposing the detection units 20a and 20b on the lower side of the first and second passages 12 and 16 and substantially facing the air vent passages 48a and 48b. It is avoided that air accumulates in the vicinity of the detection units 20a and 20b, and is not affected by the air when detection is performed by the detection units 20a and 20b. As a result, the pressures P1 and P2 of the liquid can be reliably detected by the detection units 20a and 20b.

  Furthermore, since the mounting holes 30a and 30b in which the detectors 20a and 20b are mounted have a structure in which air is easily discharged to the first and second passages 12 and 16, the air is inserted into the mounting holes 30a and 30b. It is possible to prevent accumulation.

  Further, as described above, even when air is mixed again for some reason after the air in the liquid is discharged, the pressures P1 and P2 detected by the detection units 20a and 20b and the pressures P1 and P2 are included. By detecting the change in the differential pressure ΔP, it is possible to specify which portion of the flow rate adjusting unit 22, the second and third pipes 38b, 38c has air, so that the air is reliably Can be removed.

  It should be noted that the method for controlling the quantitative discharge device according to the present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 ... Fixed quantity discharge apparatus 12 ... 1st channel | path 14 ... 1st housing 16 ... 2nd channel | path 18 ... 2nd housing 20a, 20b ... Detection part 22 ... Flow volume adjustment part 24a, 24b ... Opening hole 26a, 26b ... Sealing plug 28a 28b ... Fitting 34 ... First port 36 ... First taper portion 38a ... First piping 38b ... Second piping 38c ... Third piping 40 ... Tanks 46a, 46b ... Holding plugs 48a, 48b ... Air vent passage 58 ... Second Port 60 ... 2nd taper part 66 ... Sensor main body 70 ... Control part 72 ... On-off valve 76 ... Orifice hole

Claims (3)

A step of outputting a valve opening command to the flow control valve to circulate the liquid in the passage;
A first pressure and a second pressure of the liquid on the upstream side and the downstream side of the flow rate adjustment unit are detected through a pair of detection units arranged along the passage, respectively, and the first pressure and the second pressure are detected. Integrating the flow rate of the liquid based on the pressure difference from the pressure to calculate the discharge amount; and
When the differential pressure is in a steady state where it is maintained constant, and the differential pressure reaches a preset steady pressure, the steady pressure is output from the valve opening command and reaches the steady pressure under the valve opening action. Calculating a correction amount based on the rising characteristics of the differential pressure until
A target value obtained by subtracting the correction amount from a preset set discharge amount is compared with the discharge amount, and when the discharge amount reaches the target value, a valve closing command is output to the flow control valve. Process,
Calculating a discharge amount from when the valve closing command is output until the flow control valve is closed;
A control method for a fixed-quantity dispensing apparatus, comprising: The control method according to claim 1,
Detecting pressure changes in the second pressure and the differential pressure, respectively, and detecting mixing of air into the liquid;
Identifying the location of the air in the passage in response to the pressure change;
A control method for a fixed-quantity dispensing apparatus, comprising: The control method according to claim 1 or 2,
The pressure generated between the current first pressure and the differential pressure detected by the detection unit with respect to the first pressure and the differential pressure when the liquid stored in advance normally flows in the passage. Detecting the change;
Identifying a portion of the passage where an abnormal pressure of the liquid occurs based on the pressure change;
A method for controlling a quantitative discharge device.

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