JP4381196B2 - Low-pressure control device and control method thereof - Google Patents

Description

  The present invention relates to a low pressure control device that outputs gas pressure with high accuracy and a control method thereof.

  In general, a pressure reducing valve is often used when the gas pressure is output under reduced pressure control. For example, as shown in FIG. 11, this pressure reducing valve is provided with a valve body 103 between a supply side path 101 and an output side path 102, and the valve body 103 is pressed against a valve seat 105 by a spring 104 to be fixed at the center of the valve body 103. The stem 106 is passed through the diaphragm chamber 107, the tip of the stem 106 is brought into contact with the hole of the relief valve 109 disposed in the center of the diaphragm 108, and a spring 112 is interposed between the diaphragm receiver 110 and the spring receiver 111. The lower end of the rotating shaft 114 of 113 is brought into contact with the spring receiver 111. Further, the output side path 102 and the diaphragm chamber 107 are connected through the hole 115, the pressure of the output side path 102 and the pressure of the diaphragm chamber 107 are made uniform, the pressure of the diaphragm chamber 107 is applied to the diaphragm 108, and the diaphragm 108 is moved up and down. The direction force is generated.

  Here, the gas pressure in the supply path 101 is set higher than the gas pressure in the output path 102, the handle 113 is rotated, the rotating shaft 114 is moved downward, the spring 112 is contracted, When the valve body 103 is urged downward, the valve body 103 is lowered and gas flows from the supply side path 101 to the output side path 102. As a result, the gas pressure in the output path 102 rises, the gas pressure in the diaphragm chamber 107 rises, and an upward force is generated in the diaphragm 108.

  When the upward force of the diaphragm 108 increases, the elastic force of the spring 112 is lost to the upward force of the diaphragm 108, the valve body 103 rises, and the supply side path 101 and the output side path 102 are blocked, The gas pressure in the side path 102 decreases, the gas pressure in the diaphragm chamber 107 decreases, and the upward force of the diaphragm 108 decreases.

  In this manner, the valve body 103 moves up and down according to the gas pressure in the output side path 102, whereby the pressure in the output side path 102 is reduced to a pressure commensurate with the elastic force of the spring 112.

  There is also provided a pressure reducing valve that uses a plurality of diaphragms to improve pressure reducing accuracy.

  By the way, in the pressure reducing valve, since the pressure of the output side path 102 is controlled by balancing the elastic force of the spring 112 and the upward force of the diaphragm 108, the pressure reducing accuracy is limited. The error with respect to the value was about 0.5 kPa.

  Alternatively, since the elastic force of the springs 104 and 112, the diaphragm 108, etc. is large and it is difficult to sufficiently reduce the elastic force, the error becomes large.

  Moreover, since the valve body 103 opens and closes between the supply side path 101 and the output side path 102, the fluctuation of the gas pressure in the output side path 102 overshoots, which also reduces the accuracy of the gas pressure in the output side path 102. It became the cause.

  Furthermore, the pressure of the output side path 102 fluctuates in hysteresis with respect to the pressure of the supply side path 101, which also causes the accuracy of the gas pressure of the output side path 102 to decrease.

  Therefore, the present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a low-pressure control device capable of outputting gas pressure with high accuracy and a control method thereof. .

In order to solve the above problems, the present invention provides a nozzle connected between a supply side path and an output side path, a rotary shaft supported rotatably, and first and second arms fixed to the rotary shaft. An electromagnetic actuator having a coil and a magnet, rotating the first arm around the rotation axis by the magnetic force between the coil and the magnet, and a flapper supported by the second arm, and arranging the flapper in the vicinity of the nozzle hole, With the gas flowing from the supply side path to the output side path, the first arm is rotated and moved by the electromagnetic actuator, the rotating shaft is rotated, and the second arm is rotated and moved by the rotation of the rotating shaft. and the gas flow rate is changed, the air conversion means conductive for adjusting the gas pressure in the output side path emitted from the nozzles by displacing the said output side through to be controlled of the electro-pneumatic conversion unit A gas pressure detecting means for detecting the gas pressure of the gas pressure detecting gas pressure detected by means feedback controls the displacement of flapper of the electro-pneumatic conversion device so as to be a target value, by the gas pressure detecting means Control means for displacing the flapper of the electropneumatic conversion means by a certain amount when the difference or ratio between the detected gas pressure and the target value exceeds a certain range, and supplies the decompressed gas pressure from the output side path is doing.

  According to the low-pressure control apparatus of the present invention, the electropneumatic conversion means is used. This electropneumatic conversion means connects a nozzle between a supply side path and an output side path, displaces a flapper in the vicinity of the nozzle hole, and changes the flow rate of gas discharged from the nozzle by displacing the flapper. is there. The flapper moves closer to or away from the nozzle hole due to the displacement, thereby increasing or decreasing the flow resistance of the gas from the nozzle and changing the gas flow rate from the nozzle. As a result, the gas flow rate from the nozzle can be controlled smoothly and finely, and the gas pressure in the output side path can be adjusted smoothly and finely. Further, the gas pressure to be controlled by the electropneumatic conversion means is detected, and the displacement of the flapper of the electropneumatic conversion means is feedback-controlled so that the detected gas pressure becomes a target value. Thereby, the gas pressure to be controlled can always be brought close to the target value, and not only the gas pressure to be controlled is adjusted smoothly and finely, but also the gas pressure to be controlled is controlled with high accuracy. Is possible.

  For example, as the electropneumatic conversion means, one in which the first arm is rotated and moved by an electromagnetic actuator, the rotating shaft is rotated, the second arm is rotated by rotating the rotating shaft, and the flapper is displaced is applied. Since such an electropneumatic conversion means does not use elastic force such as a spring or a diaphragm, the gas pressure to be controlled can be controlled with extremely high accuracy.

  In feedback control, as the difference or ratio between the gas pressure in the output side path and the target value increases, the control amount also increases, which causes an overshoot of the gas pressure in the output side path. Therefore, when the difference or ratio between the detected gas pressure and the target value exceeds a certain range, instead of feedback control, the flapper of the electropneumatic conversion means is displaced by a certain amount smaller than the control amount by feedback control. ing. Therefore, as long as the difference or ratio between the detected gas pressure and the target value exceeds a certain range, the flapper of the electropneumatic conversion means is displaced by a certain amount, and the detected gas pressure gradually approaches the target value, When the difference or ratio between the detected gas pressure and the target value falls below a certain range, the control is returned to the feedback control. Thereby, the overshoot of the gas pressure to be controlled is prevented, and high-precision control of the gas pressure to be controlled is maintained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a first embodiment of the low-pressure control apparatus of the present invention. The low-pressure control device of the present embodiment detects an electropneumatic converter 1 for reducing the gas pressure, and a differential pressure between the gas pressure reduced by the electropneumatic converter 1 and the external pressure outside the low-pressure control device main body. A pressure sensor 2 and a control unit 3 for controlling the electropneumatic converter 1 are provided. The control unit 3 includes a logic circuit, a CPU, or the like, and a detection signal I (out) of the pressure sensor 2 indicating a differential pressure between the gas pressure reduced by the electropneumatic converter 1 and the external pressure outside the low pressure control device main body. The input signal I (in) indicating the target value of the differential pressure is input and the detection signal I (out) and the input signal I (in) are processed to derive the drive current level of the electropneumatic converter 1. Then, this level of drive current is applied to the electropneumatic converter 1, and the electropneumatic converter 1 is controlled so that the differential pressure becomes a target value. The control by the control unit 3 will be described in detail later.

  The electropneumatic converter 1 is an electropneumatic conversion proposed in Japanese Patent Application Laid-Open Nos. 7-190448, 7-190449, and 9-145537 previously filed by the applicant of the present invention. It is a modified mechanism. FIG. 2 is a longitudinal sectional view showing the electropneumatic converter.

  As is clear from FIG. 2, the electropneumatic converter 1 includes a gas path housing 4 and an electromagnetic drive housing 5 assembled thereto. In the gas path housing 4, the supply side path 11 and the output side path A12 are connected to the gas chamber 13, and the pressure sensor 2 for detecting the gas pressure is provided in the output side path A12. The relief path 14 is connected to the gas chamber 13, and a nozzle 15 is provided at the end of the relief path 14.

  The supply side path 11 is connected to a pressure source (not shown) through a primary side path 16, and an orifice 17 is inserted into the primary side path 16. The output side path B18 is connected to the gas pressure receiving side (not shown) through the secondary side path 19, and the electromagnetic valve 30 is connected to the output side path B18. However, even if the solenoid valve 30 is not connected, the operation as a low pressure control device does not hinder.

  In FIG. 2, configurations related to the primary side path 16 and the secondary side path 19 are schematically shown.

  The solenoid valve 30 is not energized and closes the output side path B18. In this state, when gas is supplied from the pressure source to the gas chamber 13 through the primary side path 16 and the supply side path 11, the gas is discharged from the nozzle 15 through the relief path 14, and the gas decompressed thereby is gas. It distribute | circulates from the chamber 13 to output side path | route A12. In this state, when the flapper 28 in the vicinity of the nozzle 15 hole is displaced, the flow rate of the gas discharged from the nozzle 15 changes, and the gas pressure in the gas chamber 13 and the output side path A12 also changes accordingly. The output side path A12 is provided with a pressure sensor 2 for detecting the gas pressure. The decompressed gas pressure in the output side path A12 flows through the output side path B18 and is supplied to the gas pressure receiving side (not shown) through the secondary side path 19 when the solenoid valve 30 is energized.

In the electromagnetic mechanism housing 5, a yoke 21 is fixed, and a permanent magnet 22 is disposed in the center of the yoke 21. Also, a hole 5a is formed in the side wall of the electromagnetic mechanism housing 5, and a pair of bearings 23, 23 and a spacer 24 are inserted and fixed in the hole 5a in the side wall so that the rotating shaft 25 can be rotated by the bearings 23, 23. I support it. Then, the first arm 26 and the second arm 27 are fixed to both ends of the rotary shaft 25, the moving coil 29 is fixed to the tip of the first arm 26, the moving coil 29 is concentrically disposed on the permanent magnet 22, A flapper 28 is supported at the tip of the two arms 27, and the flapper 28 is disposed in the vicinity of the nozzle 15 hole.

  FIG. 3 is a perspective view showing the periphery of the rotary shaft 25, the first arm 26, and the second arm 27. FIG. As is apparent from FIG. 3, the first arm 26 and the second arm 27 are rotatably supported by the rotating shaft 25, and the bobbin 29a of the moving coil 29 is screwed to the tip of the first arm 26 to thereby form a cylindrical permanent magnet. 22 and the central portion of the yoke 21, the cylindrical moving coil 29, and the outer periphery of the cylindrical yoke 21 are arranged concentrically, and the flapper 28 at the tip of the second arm 27 is arranged to face the nozzle 15 hole. A washer 31 made of a magnetic material such as iron or steel is provided between the moving coil 29 and the first arm 26.

  Here, when the moving coil 29 is not energized, the magnetic force of the moving coil 29 is not generated, the magnetic force of the permanent magnet 22 and the yoke 21 attracts the washer 31, and the moving coil 29 is attracted to the initial position on the permanent magnet 22 side. It is done.

  Next, when the drive current from the control unit 3 in FIG. 1 flows to the moving coil 29, the moving coil 29 receives a force due to Fleming's law in the magnetic field formed by the permanent magnet 22 and the yoke 21. Is displaced, and the tip of the first arm 26 is lowered. Along with this, the rotating shaft 25 rotates, the tip of the second arm 27 also descends, the flapper 28 moves away from the nozzle 15, and the gas flow rate discharged from the nozzle 15 changes.

  At this time, the gas pressure in the gas chamber 13 and the output side path A12 is kept constant in a state where the force received by the moving coil 29 and the force received by the flapper 28 from the gas pressure from the nozzle 15 are balanced. Therefore, the control unit 3 in FIG. 1 controls the pressure of the gas chamber 13 and the output side path A12 to be reduced by adjusting the driving current value flowing through the moving coil 29 and increasing the force received by the moving coil 29. Can do.

  The moving coil 29 needs to operate with as little resistance as possible to ensure performance. In addition, the moving coil 29 tends to be in an extremely unstable state in which fine amplitude is repeated due to the pulsation of the air pressure discharged from the nozzle 15. When a conductive nonmagnetic material such as aluminum is used for the bobbin 29a of the moving coil 29, the movement of the moving coil 29 can be stabilized and the pulsation of the air pressure discharged from the nozzle 15 can be reduced.

 As shown in FIG. 4, in the magnetic field formed by the permanent magnet 22 and the yoke 21, when an upward force F due to the gas discharged from the nozzle 15 acts on the moving coil 29, the moving coil 29 is applied to the moving coil 29 according to Fleming's right hand rule. An induced current that is perpendicular to the plane of the paper and downwards is generated. Then, as shown in FIG. 5, in the magnetic field formed by the permanent magnet 22 and the yoke 21, when a downward induced current is generated in the moving coil 29 perpendicular to the paper surface, the moving coil 29 is directed downward according to Fleming's left-hand rule. Force F 'acts. The downward force F ′ cancels the upward force F and thus acts to suppress the movement of the moving coil 29. If a conductive nonmagnetic material is used for the bobbin 29a of the moving coil 29, the induced current of the moving coil 29 is increased, and the movement of the moving coil 29 can be effectively suppressed.

  Actually, the moving coil 29 vibrates in the vertical direction, and a vibration that is 180 degrees out of phase due to the induced current of the moving coil 29 is generated in the moving coil 29, canceling both vibrations, and moving the moving coil 29. Stabilize.

  In addition to making the bobbin of the moving coil a conductive non-magnetic material, the gap between the moving coil 29 and the permanent magnet 22 and the yoke 21 is narrowed, the mass of the moving coil 29 is reduced, the magnetic force of the permanent magnet 22 is reduced. Even if the value is increased, the movement of the moving coil 29 is stabilized.

  Further, the washer 31 between the moving coil 29 and the first arm 26 is attracted by the magnetic force of the permanent magnet 22 and the yoke 21 when the moving coil 29 is not energized, and attracts the moving coil 29 to the initial position on the permanent magnet 22 side. In addition, it also serves to stabilize the operation of the moving coil 29 by suppressing the excessive operation of the moving coil 29 during energization. The washer 31 may be a spring washer, a plain washer, or a combination of these. Here, a plain washer is used, and the washer 31 is fixed by a screw that connects the first arm 26 to the moving coil 29. Thereby, the number of parts can be reduced, the configuration is simplified, and the number of assembly steps is reduced, so that a significant cost reduction can be achieved. In addition, by changing the size of the washer 31, the force for attracting the moving coil 29 to the permanent magnet 22 side can be adjusted to adjust the initial position of the moving coil 29 when not energized. The initial gas pressure of the gas chamber 13 and the output side path A12 can be set by adjusting the initial position.

  Further, instead of the combination of the moving coil 29, the permanent magnet 22, and the yoke 21, the coil may be fixed on the electromagnetic mechanism housing 5 side and the movable iron piece may be provided on the first arm 26 side.

  In FIG. 1, the pressure sensor 2 detects a differential pressure between the gas pressure on the output side path of the electropneumatic converter 1 and the external air pressure outside the low pressure control device main body, and a detection signal I (out that indicates this differential pressure. ) Is output to the control unit 3. Further, an input signal I (in) indicating the target value of the differential pressure is set by operating a volume (not shown) or the like, and this input signal I (in) is applied to the control unit 3. When the control unit 3 inputs the detection signal I (out) and the input signal I (in), whether or not {I (in) × α} ≦ I (out) ≦ {I (in) × β} That is, it is determined whether or not the ratio of the target value to the differential pressure between the gas pressure on the output side path and the external pressure is within a certain range, and if it is within the certain range, the detection signal I (out) and the input signal I The deviation of (in) is obtained, and the driving current of the moving coil 29 of the electropneumatic converter 1 is obtained so that the differential pressure becomes the target value by the calculation processing of PID control using this deviation, and this driving current is moved. Flow through coil 29. As a result, the moving coil 29 is displaced, the flapper 28 comes into contact with and separates from the nozzle 15, the flow rate of the gas discharged from the nozzle 15 changes, and the differential pressure between the gas pressure in the output side path and the external air pressure is the target. Approaching the value.

  As long as the ratio of the target value to the differential pressure between the gas pressure on the output side path and the external air pressure is within a certain range, the PID control is continued, and the driving current is set so that the differential pressure becomes the target value. 29, the flapper 28 comes into contact with and separates from the nozzle 15, the flow rate of the gas discharged from the nozzle 15 changes, and this differential pressure approaches the target value.

  Further, if the ratio of the target value to the differential pressure between the gas pressure in the output side path and the external pressure is out of a certain range, the control unit 3 does not perform the PID control, and instead, this differential pressure is set to the target value. The driving current of the moving coil 29 is increased / decreased by a certain width so as to approach. As a result, the moving coil 29 is slightly displaced, the flapper 28 is slightly in contact with and separated from the nozzle 15, the gas flow rate discharged from the nozzle 15 is changed, and the gas pressure of the output side path and the external air pressure are changed. The differential pressure slightly approaches the target value.

  As long as the ratio of the target value to the differential pressure between the gas pressure on the output side path and the external pressure is out of a certain range, a slight increase / decrease in the driving current of the moving coil 29 is repeated instead of the PID control. The differential pressure gradually approaches the target value.

  In this way, if the ratio (or difference) of the target value to the differential pressure between the gas pressure on the output side path and the external pressure is not large and falls within a certain range, the deviation between the detection signal I (out) and the input signal I (in) The pressure difference is quickly brought close to the target value by PID control using the.

  In addition, when the ratio (or difference) of the target value to the differential pressure between the gas pressure on the output side path and the external air pressure is too large and does not fall within a certain range, a slight increase / decrease in the driving current of the moving coil 29 is repeated, The differential pressure between the gas pressure on the output side path and the external air pressure is gradually brought closer to the target value.

  Instead of increasing / decreasing the driving current of the moving coil 29 by a certain width, even if the input signal I (in) is continuously applied as the driving current to the moving coil 29 of the electropneumatic converter 1, the gas pressure in the output side path The differential pressure from the outside air pressure can be gradually brought closer to the target value.

  Here, when the ratio (or difference) of the target value to the differential pressure between the gas pressure of the output side path and the external pressure is too large and does not fall within a certain range, PID control is not performed, and instead the moving coil 29 The driving current is slightly increased or decreased, or the input signal I (in) is used as it is as the driving current. This is because if the PID control is performed, the driving current of the moving coil 29 is significantly changed so that the differential pressure approaches the target value, and the flow rate of the gas discharged from the nozzle 15 changes greatly. It becomes unstable and overshoots.

  6A and 6B show the response characteristics of the differential pressure when the differential pressure between the gas pressure in the output side path and the external air pressure is too larger than the target value in the state where PID control is being performed. And a graph showing the response characteristics of the differential pressure obtained when the differential pressure is too smaller than a target value. As is apparent from these graphs, if the ratio (or difference) of the target value to the differential pressure between the gas pressure on the output side path and the external air pressure is too large, the driving current of the moving coil 29 is significantly changed. This differential pressure becomes unstable and overshoots.

  7 (a) and 7 (b) show the state in which the input signal I (in) is continuously applied to the moving coil 29 of the electropneumatic converter 1 as the drive current while the gas pressure and the external pressure of the output side path are 3 is a graph showing the differential pressure response characteristic when the differential pressure is too large than the target value, and a graph showing the differential pressure response characteristic when the differential pressure is too small than the target value. As is apparent from these graphs, if the input signal I (in) is continuously applied to the moving coil 29 of the electropneumatic converter 1, the differential pressure between the gas pressure on the output side path and the external pressure stably reaches the target value. And converge.

  As described above, in the low-pressure control apparatus according to the present embodiment, the electropneumatic converter 1 is used in which the drive current is supplied to the moving coil 29 to displace the flapper 28 and the gas pressure in the output side path is controlled to be reduced. The pressure sensor 2 detects the differential pressure between the gas pressure on the output side path and the external atmospheric pressure, and controls the drive current of the moving coil 29 of the electropneumatic converter 1 so that the detected differential pressure becomes the target value. Therefore, this differential pressure can be adjusted smoothly and finely and controlled with high accuracy.

  In the low-pressure control apparatus of this embodiment, for example, the target value of the differential pressure between the gas pressure on the output side path and the external air pressure is set to 0.3 kPa to 10 kPa, and the error of this differential pressure is suppressed to ± 0.01 kPa. it can. Such high-precision pressure control cannot be achieved with a conventional pressure reducing mechanism using an elastic force such as a spring or a diaphragm.

  For example, it can be used to inflate the resin tube with the low-pressure control device of this embodiment. In this case, since the differential pressure between the air pressure sent from the output side path of the electropneumatic converter 1 to the resin tube and the external pressure outside the low pressure control device main body is maintained constant, the resin tube has a constant inner diameter. Can be inflated with high accuracy.

  Alternatively, the low-pressure control device of the present embodiment can be used for detection of porous products such as hollow fibers, and for prevention of changes in the liquid outflow rate due to changes in the liquid surface height of the sealed container.

  FIG. 8 is a block diagram showing Example 2 of the low-pressure control apparatus of the present invention. The low-pressure control device of the present embodiment includes first and second electropneumatic converters 41 and 42 for reducing the gas pressure, and the gas pressure and low pressure reduced by the first and second electropneumatic converters 41 and 42. A pressure sensor 2 for detecting a differential pressure from the outside air pressure outside the control device main body, and a control unit 3A for controlling the first and second electropneumatic converters 41 and 42 are provided.

  The first and second electropneumatic converters 41 and 42 have the same configuration as the electropneumatic converter 1 shown in FIG. 2, and join the supply side paths 11 of the first and second electropneumatic converters 41 and 42. At the same time, the output side paths of the first and second electropneumatic converters 41 and 42 are merged, and the pressure sensor 2 is provided in the output side path.

  When the control unit 3A receives the detection signal I (out) from the pressure sensor 2 and the input signal I (in) set by the volume or the like, {I (in) × α} ≦ I (out) ≦ {I (in) × β}, that is, whether or not the ratio of the target value to the differential pressure between the gas pressure in the output side path and the external pressure is within a certain range. For example, the driving current of the moving coil of the first electropneumatic converter 41 such that the differential pressure becomes the target value by the arithmetic processing of the PID control using the deviation between the detection signal I (out) and the input signal I (in). And this drive current is passed through the moving coil of the first electropneumatic converter 41.

  In the first electropneumatic converter 41, the moving coil is displaced, the flapper 28 comes in contact with and away from the nozzle 15, the flow rate of the gas discharged from the nozzle 15 changes, and the gas pressure and the external air pressure in the output side path are changed. The differential pressure approaches the target value.

  As long as the ratio of the target value to the differential pressure between the gas pressure on the output side path and the external air pressure is within a certain range, the PID control of the first electropneumatic converter 41 is continued, and this differential pressure approaches the target value.

  In addition, if the ratio of the target value to the differential pressure between the gas pressure in the output side path and the external pressure is out of a certain range, the control unit 3A does not perform PID control, so that the differential pressure approaches the target value. The driving current of the moving coil of the second electropneumatic converter 42 is increased or decreased by a certain width.

  In the second electropneumatic converter 42, the moving coil is slightly displaced, the flapper is slightly in contact with and separated from the nozzle, the gas flow rate discharged from the nozzle is changed, and the gas pressure and the external pressure in the output side path are changed. The pressure difference between and slightly approaches the target value.

  Control of the second electropneumatic converter 42 instead of PID control of the first electropneumatic converter 41 as long as the ratio of the target value to the differential pressure between the gas pressure on the output side path and the external pressure is out of a certain range. Is continued, and a slight increase / decrease in the driving current of the moving coil is repeated, and this differential pressure gradually approaches the target value.

  Instead of increasing or decreasing the driving current of the moving coil of the second electropneumatic converter 42 by a certain width, the input signal I (in) may be continuously applied to the moving coil of the second electropneumatic converter 42 as the driving current. good.

  In this embodiment as well, the same operations and effects as those in Embodiment 1 can be achieved.

  FIG. 9 is a block diagram showing Embodiment 3 of the low-pressure control apparatus of the present invention. The low-pressure control device of the present embodiment includes first and second electropneumatic converters 51 and 52 for reducing the gas pressure, and the gas pressure and low pressure reduced by the first and second electropneumatic converters 51 and 52. A pressure sensor 2 that detects a differential pressure from the outside air pressure outside the control device main body, and a control unit 3B for controlling the first and second electropneumatic converters 51 and 52 are provided.

  The first and second electropneumatic converters 51 and 52 have the same configuration as the electropneumatic converter 1 shown in FIG. 2, and join the supply side paths of the first and second electropneumatic converters 51 and 52. The output side paths of the first and second electropneumatic converters 51 and 52 are merged, and the pressure sensor 2 is provided in the output side path.

  When the control unit 3B inputs the detection signal I (out) from the pressure sensor 2 and the input signal I (in) set by the volume or the like, the target value for the differential pressure between the gas pressure on the output side path and the external air pressure Is within a certain range, and if it is within the certain range, the first processing is performed by PID control calculation processing using the deviation between the detection signal I (out) and the input signal I (in). And the drive current of the moving coil of the 2nd electropneumatic converters 51 and 52 is calculated | required, and this drive current is sent through the moving coil of the 1st and 2nd electropneumatic converters 51 and 52.

  In the first and second electropneumatic converters 51 and 52, the moving coil is displaced, the flapper comes in contact with and away from the nozzle, the gas flow rate discharged from the nozzle changes, and the gas pressure in the output side path is The differential pressure from the atmospheric pressure approaches the target value.

  As long as the ratio of the target value to the differential pressure between the gas pressure on the output side path and the external pressure is within a certain range, the PID control of the first and second electropneumatic converters 51 and 52 is continued. It approaches the target value.

  Further, if the ratio of the target value to the differential pressure between the gas pressure on the output side path and the external air pressure is out of a certain range, the control unit 3B does not perform the PID control, and the first and second electropneumatic converters 51 , 52, the driving current of the moving coil is increased or decreased by a certain width.

  In the first and second electropneumatic converters 51 and 52, the moving coil is slightly displaced, the flapper slightly contacts and separates from the nozzle, the flow rate of gas discharged from the nozzle changes, and the output side path The differential pressure between the gas pressure and the external pressure slightly approaches the target value.

  As long as the ratio of the target value to the differential pressure between the gas pressure on the output side path and the external air pressure is out of a certain range, the driving current of the moving coils of the first and second electropneumatic converters 51 and 52 is slightly increased or decreased. Repeatedly, this differential pressure gradually approaches the target value.

  Instead of increasing or decreasing the driving current of the moving coils of the first and second electropneumatic converters 51 and 52 by a certain width, the input signal I (in) is used as it is as the driving current, and the first and second electropneumatic converters 51 are used. , 52 may be added to the moving coil.

  In this embodiment, the same operations and effects as in Embodiment 1 can be achieved, and the first and second electropneumatic converters 51 and 52 are connected in parallel. Can be doubled.

  FIG. 10 is a block diagram showing Embodiment 4 of the low-pressure control apparatus of the present invention. The low-pressure control device of the present embodiment detects an electropneumatic converter 1 for reducing the gas pressure, and a differential pressure between the gas pressure reduced by the electropneumatic converter 1 and the external pressure outside the low-pressure control device main body. A pressure sensor 2 and a control unit 3C for controlling the electropneumatic converter 1 are provided.

  When the control unit 3C inputs the detection signal I (out) from the pressure sensor 2 and the input signal I (in) set by the volume or the like, whether or not I (in) = I (out), that is, It is determined whether or not the differential pressure between the gas pressure on the output side path and the external pressure matches the target value. If not, I (in) <I (out) and I (in)> I (out) If I (in) <I (out), the driving current of the moving coil of the electropneumatic converter 1 is decreased by a certain width, and I (in)> I (out) If there is, the driving current of the moving coil of the electropneumatic converter 1 is increased by a certain width.

  In the electropneumatic converter 1, the moving coil is slightly displaced, the flapper is slightly touched and separated from the nozzle, and the gas flow rate discharged from the nozzle is decreased or increased, so that the gas pressure in the output side path The pressure difference from the atmospheric pressure slightly approaches the target value. As long as I (in) <I (out) and I (in)> I (out), the control for repeatedly increasing / decreasing the driving current of the moving coil of the electropneumatic converter 1 by a certain width is repeated. Approaches the target value.

  Further, if I (in) = I (out), the control unit 3C determines that the differential pressure between the gas pressure on the output side path and the external air pressure matches the target value, so that the moving coil of the electropneumatic converter 1 Continue to maintain the drive current.

  Such a simple feedback control can also control the differential pressure between the gas pressure on the output side path and the external air pressure.

  The present invention is not limited to the above embodiments, and can be variously modified. For example, the present invention is not limited to PID control, and various other known feedback controls can be applied. Three or more electropneumatic converters may be connected in parallel.

  Further, the electropneumatic converter may be modified. For example, the fulcrum of the arm may be supported rotatably, a flapper may be provided at the working point of the arm, and the force point of the arm may be displaced by an actuator to displace the flapper at the fulcrum of the arm. Alternatively, the flapper may be supported by a link mechanism or the like, and the flapper may be displaced by an actuator via the link mechanism.

It is a block diagram which shows Example 1 of the low voltage | pressure control apparatus of this invention. It is a longitudinal cross-sectional view which shows the electropneumatic converter in the low voltage | pressure control apparatus of FIG. It is a perspective view which shows the rotating shaft, the 1st arm, and the 2nd arm periphery in the electropneumatic converter of FIG. It is the figure used in order to demonstrate the effect | action of the permanent magnet, the yoke, and the moving coil in the electropneumatic converter of FIG. It is the figure used in order to demonstrate the operation | movement following FIG. (A) and (b) show the response characteristics of the differential pressure when the differential pressure between the gas pressure of the output side path A and the external pressure is too larger than the target value in the state where the PID control is performed. 2 is a graph showing the differential pressure response characteristics obtained when the differential pressure is too small than a target value. (A) and (b) are states in which the input signal I (in) is directly applied to the moving coil of the electropneumatic converter as the drive current, and the differential pressure between the gas pressure in the output side path A and the external air pressure is FIG. 5 is a graph showing the differential pressure response characteristic when the pressure difference is too large, and a graph showing the differential pressure response characteristic when the differential pressure is too small. FIG. It is a block diagram which shows Example 2 of the low voltage | pressure control apparatus of this invention. It is a block diagram which shows Example 3 of the low voltage | pressure control apparatus of this invention. It is a block diagram which shows Example 4 of the low voltage | pressure control apparatus of this invention. It is a longitudinal cross-sectional view which shows a common pressure reducing valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electropneumatic converter 2 Pressure sensor 3 Control part 4 Gas path housing 5 Electromagnetic drive housing 11 Supply side path 12 Output side path A
13 Gas chamber 14 Relief path 15 Nozzle 16 Primary side path 17 Orifice 18 Output side path B
19 Secondary path 21 Yoke 22 Permanent magnet 25 Rotating shaft 26 First arm 27 Second arm 28 Flapper 29 Moving coil 30 Electromagnetic valve 31 Washer

Claims (1)

A nozzle connected between the supply-side path and the output-side path; a rotary shaft rotatably supported; first and second arms fixed to the rotary shaft; a coil and a magnet; It has an electromagnetic actuator that rotates the first arm around the rotation axis by the magnetic force and a flapper supported by the second arm, and a flapper is arranged in the vicinity of the nozzle hole so that gas flows from the supply side path to the output side path. In this state, the first arm is rotated by the electromagnetic actuator, the rotating shaft is rotated, the second arm is rotated by rotating the rotating shaft, and the flapper is displaced to displace the gas flow rate discharged from the nozzle. And an electropneumatic conversion means for adjusting the gas pressure in the output side path,
A gas pressure detecting means for detecting the gas pressure in the output side path to be controlled of the electro-pneumatic conversion unit,
The gas pressure detecting gas pressure detected by means feedback controls the displacement of flapper of the electro-pneumatic conversion device so as to be a target value, the difference or the ratio of the detected gas pressure and the target value by the gas pressure detecting means Control means for displacing the flapper of the electro-pneumatic conversion means by a certain amount when exceeds a certain range ,
A low-pressure control apparatus that supplies a decompressed gas pressure from the output side path .

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