JP2011075309A - Flowmeter and mass flow controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flowmeter and a mass flow controller capable of preventing the generation of particles caused by the contact of a float with an inner wall surface of a flow channel. <P>SOLUTION: A flow channel 12 making a liquid flow from downward to upward is formed vertically inside a casing 11. A tapered surface 16 is formed of a tapered pipe 15 at a part of the channel 12. A float 20 containing a bar magnet 21 is housed in the flow channel 12. A lower ring magnet 30 and an upper ring magnet 35 of a ring-shaped permanent magnet are provided around an outer periphery of the casing 11. A repulsive force generated by the repulsion of the same magnetic poles is applied to a lower end and an upper end, respectively, of the bar magnet 21 of the float 20 from both the lower ring magnet 30 and the upper ring magnet 35. Thereby, the float 20 is always prevented from contacting with the inner wall surface of the flow channel regardless of he existence or non-existence of fluid, and consequently the generation of particles can also be prevented. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a flow meter and a mass flow controller using a float incorporating a magnet.

  Conventionally, a float type flow meter in which a float (float) is accommodated in a conical tube (taper tube) is widely used as a flow meter for measuring a flow rate of a fluid such as gas or liquid. The float type flow meter is also referred to as an area type flow meter, and the flow area is increased or decreased depending on the position of the float in the taper tube. Therefore, the float moves up and down depending on the flow rate, and the flow rate is measured from the balanced position. .

  2. Description of the Related Art A float type flow meter is known that has a magnet built in a float and measures the height position of the float by detecting the magnetism. For example, Patent Document 1 discloses a float type flow meter that includes a magnet in a float and detects a float position by a Hall IC element disposed on a side surface of a tapered tube to measure a flow rate. Patent Document 2 discloses a configuration in which a plurality of magnetic sensors are provided at substantially equidistant positions from a symmetry axis on a plane perpendicular to the symmetry axis of a magnet in an area type flow meter having a magnet built in a float. ing. Further, Patent Document 3 discloses a float type flow meter that includes a magnetic material in a float and detects displacement of the float by applying magnetism from the outside of the float.

JP 2000-65612 A JP-A-7-198433 JP 2006-343323 A

  However, in the conventional float type flow meter, the float contacts the inner wall surface (mainly the bottom surface) of the flow path when there is no fluid inside or when no fluid is flowing (flow rate is 0). Was. Even when the fluid is flowing, if the flow rate or pressure changes abruptly, the float may rub against or collide with the inner wall surface (mainly the side surface and the upper surface) of the flow path. Particles are generated when the float contacts, scrapes or collides with the inner wall surface of the flow path. When a float type flow meter is applied to a device for processing a substrate for precision electronic parts such as a semiconductor wafer, if particles are generated inside the flow meter, the particles are supplied to the substrate together with the processing liquid and attached to the substrate. The problem of adversely affecting the results arises.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a flow meter and a mass flow controller that can prevent generation of particles due to contact of the float with the inner wall surface of the flow path.

  In order to solve the above-mentioned problem, the invention of claim 1 is a flow meter, in which one end of a cylindrical shape is a primary side that is a flow path inlet, and the other end is a secondary side that is a flow path outlet. A cylindrical casing formed on the inside with a flow path for flowing fluid along the cylindrical longitudinal direction; and a rod-shaped float housed in the flow path along the flow path and containing a bar magnet; A primary magnet attached to the primary side of the casing and exerting repulsive force on the primary end of the bar magnet; and a secondary magnet attached to the secondary side of the casing and exerting repulsive force on the secondary end of the bar magnet. A secondary side magnet.

  According to a second aspect of the present invention, in the flowmeter according to the first aspect of the invention, the primary side magnet and the secondary side magnet have a ring shape and are provided around the outer peripheral surface of the casing. And

  According to a third aspect of the present invention, in the flowmeter according to the second aspect of the invention, the primary magnet has an NS magnetic pole formed in the longitudinal direction of the casing, and the secondary magnet has a ring-shaped inner peripheral side. NS magnetic poles are formed on the outer peripheral side.

  According to a fourth aspect of the present invention, in the flowmeter according to any one of the first to third aspects of the present invention, the magnet disposed on the longitudinal extension of the bar magnet of the float accommodated in the flow path. The apparatus further includes a sensor and a measurement unit that detects a position of the float in the casing based on an output from the magnetic sensor and measures a flow rate of the fluid flowing through the flow path.

  According to a fifth aspect of the present invention, in the flowmeter according to the fourth aspect of the present invention, the casing is installed such that the flow path inlet is at the bottom and the flow path outlet is at the top. A flow direction changing member provided at an upper portion and changing a flow direction of the fluid flowing from the lower side to the upper side of the flow path is further provided, and the magnetic sensor is provided at an upper portion of the flow direction changing member. .

  According to a sixth aspect of the present invention, in the flowmeter according to the fourth or fifth aspect of the present invention, the position of the float in the casing is adjusted to a predetermined position based on an output from the magnetic sensor. It further comprises an electromagnet that exerts a magnetic force on the bar magnet so that the flow rate of the fluid flowing through the flow path becomes a predetermined amount.

  The invention according to claim 7 is the mass flow controller for adjusting the flow rate of the fluid to a predetermined amount, wherein one end of the cylindrical shape is a primary side that is a flow path inlet, and the other end is a secondary side that is a flow path outlet. As a cylindrical casing formed with a flow path for flowing fluid along the cylindrical longitudinal direction, and a rod-shaped casing housed in the flow path so as to be movable along the flow path and incorporating a bar magnet A float, a primary magnet attached to the primary side of the casing and exerting a repulsive force on the primary side end of the bar magnet; a secondary magnet attached to the secondary side of the casing; and a repulsive force applied to the secondary side end of the bar magnet And a magnetic sensor disposed on a longitudinal extension of the bar magnet of the float accommodated in the flow path, and the float in the casing based on an output from the magnetic sensor. Detecting the position Based on an output from the magnetic sensor and a measurement unit that measures the flow rate of the fluid flowing through the path, the flow rate of the fluid flowing through the flow path is adjusted to a predetermined amount by adjusting the position of the float in the casing to a predetermined position. And an electromagnet that exerts a magnetic force on the bar magnet.

  According to the first to sixth aspects of the present invention, the rod-shaped float containing the bar magnet is attached to the primary side of the casing that is movably accommodated along the flow path, and the repulsive force is applied to the primary side end of the bar magnet. A primary side magnet that acts on the secondary side of the casing, and a secondary side magnet that exerts repulsive force on the secondary side end of the bar magnet. And the generation of particles due to contact of the float with the inner wall surface of the flow path can be prevented.

  In particular, according to the invention of claim 2, since the primary side magnet and the secondary side magnet have a ring shape and are provided around the outer peripheral surface of the casing, the float is stably maintained in the casing without contact. be able to.

  In particular, according to the invention of claim 4, since the magnetic sensor is arranged on the longitudinal extension line of the rod magnet of the float accommodated in the flow path, the position of the float can be detected with high accuracy. The flow rate of fluid can be measured accurately.

  In particular, according to the sixth aspect of the present invention, the bar magnet is adjusted so that the flow rate of the fluid flowing through the flow path becomes a predetermined amount by adjusting the position of the float in the casing to a predetermined position based on the output from the magnetic sensor. Since an electromagnet that exerts a magnetic force is further provided, a flow rate adjusting function can also be imparted to the flow meter.

  Further, according to the invention of claim 7, the primary float that is attached to the primary side of the casing that accommodates the rod-like float containing the bar magnet so as to be movable along the flow path, and exerts repulsive force on the primary side end of the bar magnet. Since the side magnet and the secondary side magnet attached to the secondary side of the casing and exerting repulsive force on the secondary side end of the bar magnet are provided, the float can always be maintained in a non-contact state inside the casing. Generation of particles due to contact of the float with the inner wall surface of the flow path can be prevented. In addition, the float is provided with an electromagnet that exerts a magnetic force on the bar magnet so that the flow rate of the fluid flowing through the flow path becomes a predetermined amount by adjusting the position of the float in the casing to a predetermined position based on the output from the magnetic sensor. The flow rate of the processing liquid can be adjusted by moving the position to a predetermined position.

It is a figure which shows the outline of the structural example of the substrate processing apparatus incorporating the flowmeter which concerns on this invention. It is a figure which shows the structure of the flowmeter which concerns on this invention. It is a figure explaining the change of the magnetic field intensity of a magnetic sensor by the height position of a float. It is a figure explaining the change of the magnetic field intensity of a magnetic sensor by the height position of a float. It is a figure which shows the other structural example of the flowmeter which concerns on this invention.

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

  First, a suitable application example of the flowmeter according to the present invention will be outlined. FIG. 1 is a diagram showing an outline of a configuration example of a substrate processing apparatus incorporating a flow meter according to the present invention. The substrate processing apparatus 1 includes a processing unit 5. The processing unit 5 is a cleaning processing unit that performs cleaning processing by discharging pure water from the cleaning nozzle 6 onto the surface of the substrate W while rotating the substrate W such as a semiconductor wafer in a horizontal plane.

  The cleaning nozzle 6 may be a straight nozzle that simply discharges pure water, or may be a two-fluid nozzle that mixes pure water and gas to generate and discharge fine water droplets. Alternatively, it may be a high-pressure cleaning nozzle that discharges high-pressure pure water. Further, an ultrasonic vibrator may be provided and the cleaning nozzle 6 may be an ultrasonic cleaning nozzle. Further, the processing unit 5 may include a cleaning unit (for example, a cleaning brush) other than the cleaning nozzle 6. Further, the processing unit 5 may supply and store pure water from the cleaning nozzle 6 into the processing tank, and may perform a cleaning process by immersing a plurality of substrates W in the pure water. Further, the substrate W to be processed in the processing unit 5 may be a substrate for precision electronic components such as a glass substrate for a liquid crystal display device.

  The cleaning nozzle 6 is connected to the processing liquid supply source 2 through a processing liquid pipe 7. In the present embodiment, the processing liquid supply source 2 supplies pure water as the processing liquid. A pump 8, a supply valve 3, a filter 4, and a flow meter 10 according to the present invention are interposed in the course of the processing liquid pipe 7. By opening the supply valve 3 while operating the pump 8, pure water is supplied from the processing liquid supply source 2 to the cleaning nozzle 6 and discharged onto the substrate W. The filter 4 removes particles contained in pure water supplied from the processing liquid supply source 2. The flow meter 10 measures the flow rate of pure water flowing through the processing liquid pipe 7. In the present embodiment, the pump 8 supplies pure water at a constant pressure.

  FIG. 2 is a diagram showing the configuration of the flow meter 10 according to the present invention. The flow meter 10 is configured by accommodating a float 20 inside a cylindrical casing 11. The casing 11 is formed of a resin material (for example, fluororesin) having excellent chemical resistance characteristics, and has a hollow cylindrical shape with an open upper end and a lower end. The flow meter 10 is provided in the processing liquid pipe 7 so that the cylindrical axis direction of the casing 11 is along the vertical direction. Accordingly, a flow path 12 is formed inside the casing 11 along the vertical direction in which a fluid flows from below to above. In the casing 11, one end of the cylindrical shape is a primary side that is an inlet of the flow path 12, and the other end is a secondary side that is an outlet of the flow path 12. The flow meter 10 of this embodiment is installed so that the primary side is down and the secondary side is up.

  The float 20 is configured by coating a surface of a bar magnet 21 with a resin layer 22 having excellent chemical resistance. The bar magnet 21 is a rod-shaped permanent magnet, and in this embodiment, an N pole is formed on the upper side which is the secondary side, and an S pole is formed on the lower side which is the primary side. The float 20 is a rod-shaped float with a built-in bar magnet 21 and has a long cylindrical shape. The diameter of the float 20 is smaller than the inner diameter of the casing 11, and the float 20 is accommodated in the flow path 12 so as to be movable up and down. In the flow meter 10 of the present embodiment, the specific gravity of the entire float 20 is greater than the specific gravity of the treatment liquid (here, pure water) that is a flow measurement target.

  A tapered tube 15 is installed along the inner wall surface of the casing 11, and the inside of the tapered tube 15 constitutes a part of the flow path 12. A tapered surface 16 is formed inside the tapered tube 15 so that the inner diameter increases from the primary side to the secondary side, that is, in the flowmeter 10 of the present embodiment, the inner diameter increases from the lower side to the upper side. Has been. The bottom of the tapered surface 16 is a float stop 17. The inner diameter at any position of the tapered surface 16 is larger than the diameter of the float 20, and at least the lower end of the float 20 fits inside the tapered surface 16. On the other hand, the float stopper 17 is formed with a cylindrical opening 18 having a diameter smaller than the diameter of the float 20. Therefore, the float 20 is prevented from falling below the float stopper 17. Further, the lower end opening 19 of the taper tube 15 is connected to the processing liquid pipe 7 and serves as a flow path inlet.

  A lower ring magnet 30 that is a primary side magnet and an upper ring magnet 35 that is a secondary side magnet are provided around the outer peripheral surface of the casing 11. In the configuration example of FIG. 2, the lower ring magnet 30 is provided around the outer peripheral surface of the casing 11 and below the center in the longitudinal direction, and the upper ring magnet 35 is provided around the upper side.

  The lower ring magnet 30 and the upper ring magnet 35 are both permanent magnets having a ring shape. In the present embodiment, as shown in FIG. 2, the lower ring magnet 30 has an S pole on the upper side of the ring shape and an N pole on the lower side. On the other hand, the upper ring magnet 35 has an N pole on the lower side of the ring shape and an S pole on the upper side.

  An L-shaped tube 40 is connected to the upper end of the casing 11. The L-shaped tube 40 is a flow direction changing member that changes the flow direction of the fluid by 90 degrees. In this embodiment, the flow of the processing liquid that has flowed from the lower side to the upper side in the flow path 12 is changed in the horizontal direction (horizontal direction). Bend to). The opening 41 at the tip of the L-shaped tube 40 is connected to the processing liquid pipe 7 and serves as a flow path outlet.

  A magnetic sensor 50 is provided above the L-shaped tube 40. In the present embodiment, a Hall sensor is used as the magnetic sensor 50. The Hall sensor is a sensor that detects a magnetic field using the Hall effect. The magnetic sensor 50 is an upper side of the L-shaped tube 40 and is accommodated in the flow channel 12 and floats in an upright posture (longitudinal direction along the vertical direction) along the central axis direction of the casing 11. It is arranged above the longitudinal direction of the bar magnet 21, that is, directly above the axial extension line of the bar magnet 21.

  The magnetic sensor 50 generates and outputs a voltage proportional to the strength of the magnetic field. The voltage signal is output from the magnetic sensor 50 and input to the calculation unit 55. The calculation unit 55 has the same configuration as that of a normal computer, and includes a CPU, a ROM, a RAM, a magnetic disk, and the like. The calculation unit 55 converts the level of the voltage signal output from the magnetic sensor 50 into the flow rate of the processing liquid flowing inside the flow meter 10 by executing a predetermined calculation program.

  Further, an electromagnet 60 is provided on the upper side of the magnetic sensor 50. The electromagnet 60 is obtained by winding a coil around an iron core, and generates a magnetic field by passing a current from the power source 61 to the coil. The value of the current flowing from the power supply 61 to the coil, that is, the magnetic force generated by the electromagnet 60 is controlled by the calculation unit 55.

  In the flow meter 10 of the present embodiment, the float 20 is in contact with the inner wall surface of the flow meter 10 even when no processing liquid is present in the casing 11 or when the processing liquid is not flowing. It is supported in a stationary state. That is, the float 20 is accommodated in the flow path 12 so as to be able to move up and down, and a repulsive force is exerted on the S pole at the lower end of the bar magnet 21 by the same magnetic pole repelling from the S pole on the upper side of the lower ring magnet 30. . Since the lower ring magnet 30 is disposed so as to surround the vicinity of the lower end of the bar magnet 21, the S pole of the lower ring magnet 30 regulates the lower end position of the bar magnet 21 to the center in the radial direction of the casing 11, and the bar magnet 21. Apply an upward force to. On the other hand, a repulsive force is exerted on the N pole at the upper end of the bar magnet 21 by the same magnetic pole repelling from the N pole below the upper ring magnet 35. Since the upper ring magnet 35 is also arranged so as to surround the vicinity of the upper end of the bar magnet 21, the N pole of the upper ring magnet 35 restricts the upper end position of the bar magnet 21 to the center in the radial direction of the casing 11.

  Therefore, even when the processing liquid is not present in the flow meter 10 or when the processing liquid is not flowing, the float 20 is supported in a floating state inside the casing 11, and the height position thereof is the float 20. Is a position where the gravitational force acting on and the upward repulsive force from the lower ring magnet 30 balance. Further, the lower ring magnet 30 and the upper ring magnet 35 position the upper end and the lower end of the float 20 at the radial center of the casing 11, respectively. As a result, the float 20 is supported in a floating state in an upright posture inside the casing 11, and the float 20 is not in contact with the inner wall surface of the flow meter 10 at all. In addition, it is preferable to provide the lower ring magnet 30 over the upper and lower sides of the float stopper 17 so that an upward force can be stably applied from the lower ring magnet 30 to the lower end of the float 20.

  When the flow rate of the processing liquid is measured by the flow meter 10 described above, the processing liquid flowing through the processing liquid pipe 7 flows into the flow path 12 from the lower end opening 19 of the taper pipe 15, and the flow path 12 is secondary from the primary side. It flows to the side, that is, from the bottom to the top, and the direction of the flow is changed in the lateral direction by the L-shaped tube 40 and flows out from the opening 41 at the tip of the L-shaped tube 40. In this process, the processing liquid moves the float 20 from the primary side to the secondary side, that is, pushes it up according to the flow rate. Specifically, the flow path area at the lower end of the float 20 increases or decreases depending on the height position of the float 20 in the tapered surface 16 of the tapered tube 15, and the float 20 is positioned closer to the secondary side, that is, above. The channel area increases as the distance increases. Therefore, when the flow rate of the processing liquid flowing in from the processing liquid pipe 7 increases, the float 20 rises so that the flow path area also increases. Conversely, when the flow rate of the processing liquid decreases, the float 20 decreases so that the flow path area also decreases. Descend. However, since the float 20 of the present embodiment is supported in a non-contact manner by magnetic levitation, even when the flow rate of the processing liquid becomes a predetermined value or less, a certain height position (the processing liquid does not flow) Sometimes the float 20 does not fall below the position where it is supported in a floating state.

  Even if the float 20 moves up and down due to fluctuations in the flow rate of the processing liquid, the float 20 always exerts a magnetic repulsive force from the lower ring magnet 30 and the upper ring magnet 35 to the lower end and the upper end of the bar magnet 21 of the float 20. It does not contact the inner wall surface of the flow meter 10. Therefore, generation of particles due to contact of the float 20 with the inner wall surface of the flow path can be prevented. As a result, clean pure water in which no particles are mixed can be discharged from the cleaning nozzle 6 onto the substrate W, and adverse effects on the processing results in the processing unit 5 can be prevented.

  The flow rate of the processing liquid flowing through the flow meter 10 can be measured by detecting the height position of the float 20 in the flow path 12. As described above, since the float 20 moves up and down according to the flow rate of the processing liquid, the flow rate of the processing liquid flowing through the flow path 12 can be obtained by detecting the height position of the float 20 that is balanced at a certain position. It is. In the present embodiment, the flow rate of the processing liquid is measured by detecting the height position of the float 20 by the magnetic sensor 50.

  The float 20 incorporates a bar magnet 21, and magnetic lines of force are formed from the N pole to the S pole of the bar magnet 21. Applying magnetism from the bar magnet 21 to the magnetic sensor 50 means that such lines of magnetic force pass through the magnetic sensor 50. The strength of the magnetic field created by the bar magnet 21 at the position of the magnetic sensor 50 is inversely proportional to the distance between the upper end of the bar magnet 21 and the magnetic sensor 50. Accordingly, as the flow rate of the processing liquid increases and the float 20 rises higher, the magnetic field strength at the position of the magnetic sensor 50 also increases. The magnetic sensor 50 is a Hall sensor that generates a voltage proportional to the strength of the magnetic field, and can detect the height position of the float 20 by measuring the level of the voltage signal output from the magnetic sensor 50. The flow rate of the processing liquid can be obtained from the height position. In the flow meter 10 shown in FIG. 2, the calculation unit 55 detects the height position of the float 20 in the casing 11 based on the signal output from the magnetic sensor 50, and measures the flow rate of the processing liquid from the height position. is doing.

  Here, in the present embodiment, the float 20 is regulated in an upright posture along the central axis of the casing 11 by the lower ring magnet 30 and the upper ring magnet 35, and the magnetic sensor 50 is the longitudinal length of the bar magnet 21 of the float 20. Since it is provided above (directly above) along the direction, a change in the height position of the float 20 can be detected with high accuracy. This will be described with reference to FIGS.

  As shown in FIG. 3, when the flow rate of the processing liquid flowing through the flow path 12 is relatively small, the float 20 is closer to the primary side, that is, the height position of the float 20 is low, and the upper ends of the magnetic sensor 50 and the float 20. And the density of magnetic lines of force passing through the magnetic sensor 50 is small. That is, the magnetic field strength at the position of the magnetic sensor 50 is weak.

  When the flow rate of the processing liquid flowing through the flow path 12 is increased from the state of FIG. 3, the float 20 is pushed up to the secondary side, and the flow rate after the increase and the flow path area at the lower end of the float 20 are balanced to the position of FIG. The float 20 rises. As shown in FIG. 4, the float 20 moves closer to the secondary side, that is, the height position of the float 20 becomes higher, the magnetic sensor 50 approaches the upper end of the float 20, and the density of magnetic lines of force passing through the magnetic sensor 50 is increased. Becomes larger. That is, the strength of the magnetic field at the position of the magnetic sensor 50 is increased. At this time, in this embodiment, since the magnetic sensor 50 is disposed on the longitudinal extension line of the bar magnet 21, the float 20 is moved up and down as compared with other positions (for example, the side of the bar magnet). The rate of change of magnetic field strength is large. Therefore, the height position of the float 20 can be detected with high accuracy, and the flow rate of the processing liquid can be accurately measured. The flow rate of the processing liquid measured by the magnetic sensor 50 and the calculation unit 55 may be displayed on a display panel (not shown), or the calculation unit 55 compares the preset appropriate range with the measured flow rate. If it is out of the proper range, an upper / lower limit alarm may be issued.

  In addition, the flow meter 10 includes an electromagnet 60. When a current is passed from the power source 61 to the coil of the electromagnet 60, a new magnetic field is generated from the electromagnet 60 and exerts a magnetic force on the bar magnet 21 of the float 20. When the float 20 moves up and down in response to the magnetic force from the electromagnet 60, the area of the gap between the primary side end of the float 20 and the tapered surface 16 of the tapered tube 15, that is, the flow path area at the lower end of the float 20 changes. Therefore, the flow rate of the processing liquid flowing through the flow passage 12 is regulated to a value corresponding to the flow path area. That is, the flow rate of the processing liquid that actively flows through the flow path 12 can be adjusted by the electromagnet 60, and the flow rate adjustment function can be added to the flow meter 10 in addition to the flow rate measurement function. A flow meter 10 having a flow rate adjusting function is the same as what is called a so-called mass flow controller.

  When adjusting the flow rate of the processing liquid by operating the electromagnet 60, the process of adjusting the height position of the float 20 in the casing 11 to a predetermined position and flowing through the flow path 12 based on the output from the magnetic sensor 50. A magnetic force is applied from the electromagnet 60 to the bar magnet 21 so that the flow rate of the liquid becomes a predetermined amount. Specifically, based on the height position of the float 20 obtained by measuring the level of the voltage signal output from the magnetic sensor 50, the calculation unit 55 maintains the height position of the float 20 at a predetermined position. The output of the power supply 61 is feedback-controlled so that Thereby, the flow rate of the processing liquid flowing through the flow path 12 is adjusted to a predetermined amount, and the flow rate of the processing liquid flowing through the processing liquid pipe 7 can be kept constant by the flow meter 10. However, since the magnetic sensor 50 is also affected by the magnetic field generated by the electromagnet 60, the calculation unit 55 performs a correction to subtract the magnetic field strength from the electromagnet 60 from the level of the signal output from the magnetic sensor 50. The height position of the float 20 is detected. Since both the magnetic sensor 50 and the electromagnet 60 are fixedly installed, the interval between them is constant, and the value of the current flowing through the coil of the electromagnet 60 is controlled by the calculation unit 55 itself. The strength of the magnetic field created at the position of the magnetic sensor 50 can be easily calculated.

  According to the flow meter 10 of the present embodiment, repulsive force due to the repulsive force of the same magnetic pole is exerted on both the lower and upper ends of the bar magnet 21 of the float 20 from both the lower ring magnet 30 and the upper ring magnet 35. The lower ring magnet 30 gives an upward force to the lower end of the bar magnet 21 and a force that stays at the radial center of the casing 11. The upper ring magnet 35 gives a downward force (a force weaker than an upward force to the lower end of the bar magnet 21) and a force staying at the radial center of the casing 11 to the upper end of the bar magnet 21. For this reason, when the processing liquid is not present in the flow meter 10 or when the processing liquid is not flowing, the float 20 is supported in an upright posture in a floating state inside the casing 11 and is supported on the inner wall surface of the flow path. Contact is prevented. Even when the processing liquid flows through the flow meter 10 and the float 20 moves up and down, the position of the bar magnet 21 is set to the central axis of the casing 11 by the repulsive force from the lower ring magnet 30 and the upper ring magnet 35. Therefore, the vertical movement of the float 20 is also along the central axis of the casing 11, and the float 20 is prevented from contacting the inner wall surface of the flow path. Therefore, the float 20 can always be maintained in a non-contact state inside the casing 11, and generation of particles due to contact of the float 20 with the inner wall surface of the flow path can be prevented.

  Further, the flow meter 10 of the present embodiment is configured such that the height position of the float 20 is determined by the magnetic sensor 50 disposed at a position directly above the longitudinal direction of the bar magnet 21 of the float 20 supported in an upright posture in the casing 11. It detects and measures the flow rate of the processing liquid. On the longitudinal extension line of the bar magnet 21 having NS magnetic poles formed at both ends, the rate of change in the strength of the magnetic field accompanying the vertical movement of the float 20 is maximized. Therefore, the change in the signal level output from the magnetic sensor 50 when the float 20 moves up and down is increased, and the height position of the float 20 can be detected with high accuracy. As a result, the flow rate of the processing liquid can be accurately measured, and the change can be accurately detected even when the flow rate changes to a very small amount. Moreover, since the magnetic field intensity from the bar magnet 21 can be detected continuously and output as a voltage signal by one magnetic sensor 50 regardless of the height position of the float 20, the resolution of the flow rate measurement is also improved. Can be expensive.

  Further, the flow meter 10 of the present embodiment can further adjust the flow rate of the processing liquid flowing through the processing liquid piping 7 by moving the height position of the float 20 to a predetermined position by including the electromagnet 60. Thereby, the flow meter 10 of this embodiment also has a function as a mass flow controller.

  While the embodiments of the present invention have been described above, the present invention can be modified in various ways other than those described above without departing from the spirit of the present invention. For example, in the above embodiment, the electromagnet 60 is provided on the upper side of the magnetic sensor 50. Instead, as shown in FIG. 5, an electromagnet 160 is provided on the outer peripheral surface of the casing 11. good. 5, the same elements as those in FIG. 2 of the above embodiment are denoted by the same reference numerals, and the configuration other than the installation position of the electromagnet 160 and the upper ring magnet 135 is the same as that in FIG. 2. As shown in FIG. 5, even if the electromagnet 160 is attached to the outer peripheral surface of the casing 11, when a current is passed from the power source 61 to the coil of the electromagnet 160, a new magnetic field is generated from the electromagnet 160 and the rod magnet 21 of the float 20 is applied. Can exert a magnetic force. At this time, similarly to the above-described embodiment, based on the height position of the float 20 obtained by measuring the level of the voltage signal output from the magnetic sensor 50, the calculation unit 55 performs the height position of the float 20. Is feedback-controlled so that is maintained at a predetermined position. Thereby, the flow volume of the process liquid which flows through the process liquid piping 7 can be adjusted to a fixed amount. The installation position of the electromagnet is not limited to the examples of FIGS. 2 and 5, and may be any position that can exert a magnetic force on the bar magnet 21 of the float 20 when the coil is energized. In FIG. 5, the upper ring magnet 135 uses a ring-shaped magnet having an N pole on the inner peripheral side and an S pole on the outer peripheral side. In addition, it is preferable to use a magnet having an N pole on the lower side of the ring shape and an S pole on the upper side, like the upper ring magnet 35 of the above embodiment, because a magnet having a relatively weak magnetic force is sufficient.

  Moreover, in the said embodiment, although the Hall sensor was used as the magnetic sensor 50, it is not limited to this, What is necessary is just a sensor which can measure the intensity | strength of a magnetic field, for example, a magnetic impedance element and a coil are used. You may do it. However, when a coil is used as the magnetic sensor 50, it is necessary to separately provide a detection circuit that can detect the height position of the float 20 that is stationary.

  Moreover, in the said embodiment, although the magnetic sensor 50 has been arrange | positioned in the position of the secondary side along the longitudinal direction of the bar magnet 21 of the float 20, ie, a position right above, the primary side along the longitudinal direction of the bar magnet 21 The magnetic sensor 50 may be arranged at the position, i.e., the position immediately below. Even at the position immediately below the longitudinal direction of the bar magnet 21, the rate of change in the strength of the magnetic field accompanying the vertical movement of the float 20 is maximized, just like the position immediately above. Therefore, as in the above embodiment, the height position of the float 20 can be detected with high accuracy, and the flow rate of the processing liquid can be accurately measured. That is, the magnetic sensor 50 may be disposed on the longitudinal extension line of the bar magnet 21 of the float 20 supported in an upright posture in the casing 11.

  In the above embodiment, the lower ring magnet 30 and the upper ring magnet 35 are ring-shaped permanent magnets, but the present invention is not limited to the ring shape, and these are arranged so as to surround the outer peripheral surface of the casing 11. A plurality of permanent magnets may be used. However, in order to give the bar magnet 21 a magnetic force that remains stably in the radial center of the casing 11, it is most preferable that the lower ring magnet 30 and the upper ring magnet 35 have a ring shape.

  Further, in the above embodiment, the S pole is formed on the upper side of the ring shape of the lower ring magnet 30, the N pole is formed on the lower side, the N pole is formed on the lower side of the ring shape of the upper ring magnet 35, and the S pole is formed on the upper side. However, the present invention is not limited to this. If the magnetic poles of the bar magnets 21 are reversed, the magnetic poles of the lower ring magnet 30 and the upper ring magnet 35 need to be reversed. That is, if the S pole is formed on the upper side of the bar magnet 21 and the N pole is formed on the lower side, the N pole is formed on the upper side of the ring shape of the lower ring magnet 30 and the S pole is formed on the lower side. It is necessary to form an S pole on the lower side of the ring shape and an N pole on the upper side.

  Further, the present invention is not limited to forming NS magnetic poles above and below the ring shape of the lower ring magnet 30. NS magnetic poles may be formed on the inner peripheral side and the outer peripheral side of the ring shape of the lower ring magnet 30.

  Further, in the above embodiment, the lower ring magnet 30 is provided around the outer peripheral surface of the casing 11 and below the center in the longitudinal direction, and the upper ring magnet 35 is provided around the upper side. The lower ring magnet 30 may be provided on the lower side of the outer peripheral surface of the casing 11 and the upper ring magnet 35 may be provided on the upper side of the outer peripheral surface. For example, the installation position of the lower ring magnet 30 may exceed the center in the longitudinal direction of the casing 11, and conversely, the installation position of the upper ring magnet 35 may exceed the center in the longitudinal direction. Further, the installation positions of the lower ring magnet 30 and the upper ring magnet 35 may exceed both longitudinal ends of the casing 11. Further, the lower ring magnet 30 and the upper ring magnet 35 may be provided with a slight gap from the outer peripheral surface of the casing 11.

  In short, the lower permanent magnet that is attached to the lower part of the casing 11 and exerts repulsive force on the primary side, that is, the lower end of the bar magnet 21, and the secondary permanent magnet that is attached to the secondary side of the casing 11, ie, the upper part. If it is a structure provided with the upper side permanent magnet which is a secondary side magnet which exerts repulsive force on the secondary side, ie, an upper end part, it will be prevented that float 20 contacts a channel inner wall surface like the above-mentioned embodiment, As a result, the generation of particles can be prevented.

  Moreover, in the said embodiment, although the height position of the float 20 was detected with the magnetic sensor 50, if it is a transparent process liquid, the height position of the float 20 will be visually recognized and the flow volume of a process liquid May be measured. Further, the flow position of the processing liquid may be measured by detecting the height position of the float 20 using an optical sensor (for example, a transmissive optical sensor).

  Moreover, in the said embodiment, although the specific gravity of the float 20 is larger than the specific gravity of the process liquid used as flow volume measurement object, you may make it the same with the specific gravity of a process liquid. In the same manner, when the processing liquid is not flowing, the float 20 is a primary magnet so that the float 20 stays at a predetermined position (for example, the same position as when the processing liquid does not flow in the above embodiment). The magnetic force received from the ring magnet 30 and / or the magnetic force received from the upper ring magnet 35 that is a secondary side magnet may be adjusted. That is, by making the specific gravity of the float 20 the same as that of the processing liquid, the magnetic force of the lower ring magnet 30 is weakened or the upper ring magnet is compensated so that the force that the float 20 is attracted to the primary side by gravity is lost. What is necessary is just to strengthen the magnetic force of 35.

  Further, the specific gravity of the float 20 may be made smaller than the specific gravity of the processing liquid that is a flow rate measurement target. Even if the processing liquid is small, the float 20 is a magnetic force received from the lower ring magnet 30 that is a primary side magnet and / or a secondary side magnet so that the float 20 remains in a predetermined position when the processing liquid does not flow. The magnetic force received from the upper ring magnet 35 may be adjusted. That is, the magnetic force of the lower ring magnet 30 is reduced or the magnetic force of the upper ring magnet 35 is reduced so that the float 20 is attracted to the secondary side by buoyancy by making the specific gravity of the float 20 smaller than that of the processing liquid. Should be strengthened.

  Moreover, in the said embodiment, although the flowmeter 10 was installed so that a primary side might be down and a secondary side might be up, you may make it upside down. In other words, when the specific gravity of the float 20 is larger than the specific gravity of the processing liquid, the float 20 receives a force in a direction attracted to the secondary side by gravity, but the float 20 remains in the predetermined position. In order to achieve this, the magnetic force of the primary magnet may be weakened and / or the magnetic force of the secondary magnet may be increased.

  Further, the flow meter 10 may be horizontal. In this case, it is optimal that the float 20 has the same specific gravity as the processing liquid. Even if the specific gravity of the float 20 is different from the specific gravity of the treatment liquid, the primary side magnet and the secondary side magnet are arranged so as to surround the bar magnet 20 of the float 20 if there is a slight difference. Is restricted to the center of the casing 11 in the radial direction.

  Moreover, you may install the flow meter 10 up and down diagonally. In short, the flow meter 10 may be installed in any direction. Furthermore, the flow meter 10 may be installed in a weightless environment.

  In the above embodiment, the calculation unit 55 has the same configuration as that of a normal computer, and the CPU executes a predetermined calculation program to calculate the flow rate of the processing liquid from the output signal of the magnetic sensor 50. However, you may make it comprise the calculating part 55 as an electric circuit which has a specific function.

Further, the treatment liquid to be measured by the flowmeter 10 according to the present invention is not limited to pure water, but hydrochloric acid (Hcl), sulfuric acid (H ₂ SO ₄ ), ammonia water (NH ₃ + H ₂ O), etc. It may be a chemical solution. Furthermore, the fluid to be measured by the flow meter 10 according to the present invention is not limited to a liquid, but may be a gas. However, the fluid to be measured by the flow meter 10 needs to be a nonmagnetic fluid.

DESCRIPTION OF SYMBOLS 1 Substrate processing apparatus 5 Processing unit 6 Cleaning nozzle 7 Processing liquid piping 10 Flowmeter 11 Casing 12 Flow path 15 Tapered tube 16 Tapered surface 20 Float 21 Bar magnet 30 Lower ring magnet 35,135 Upper ring magnet 40 L-shaped tube 50 Magnetic sensor 55 Calculation part 60,160 Electromagnet W board

Claims (7)

A cylinder in which one end of the cylinder is a primary side which is a flow path inlet and the other end is a secondary side which is a flow path outlet, and a flow path for flowing fluid along the cylindrical longitudinal direction is formed inside Shaped casing,
A rod-like float that is movably accommodated along the flow channel in the flow channel and incorporates a bar magnet;
A primary magnet attached to a primary side of the casing and exerting a repulsive force on a primary side end of the bar magnet;
A secondary magnet attached to the secondary side of the casing and exerting a repulsive force on the secondary side end of the bar magnet;
A flow meter comprising: The flow meter according to claim 1, wherein
The flowmeter according to claim 1, wherein the primary side magnet and the secondary side magnet have a ring shape and are provided around the outer peripheral surface of the casing. The flow meter according to claim 2, wherein
The primary magnet has an NS magnetic pole formed in the longitudinal direction of the casing,
The flowmeter according to claim 2, wherein the secondary magnet is formed with NS magnetic poles on an inner peripheral side and an outer peripheral side of a ring shape. In the flow meter according to any one of claims 1 to 3,
A magnetic sensor disposed on a longitudinal extension of the bar magnet of the float housed in the flow path;
A measurement unit that detects a position of the float in the casing based on an output from the magnetic sensor and measures a flow rate of the fluid flowing through the flow path;
A flow meter further comprising: The flow meter according to claim 4, wherein
The casing is installed so that the flow path inlet is on the bottom and the flow path outlet is on the top,
A flow direction changing member that is provided in an upper part of the casing and changes a flow direction of the fluid flowing upward from the lower side of the flow path;
The magnetic sensor is provided on an upper part of the flow direction changing member. In the flow meter according to claim 4 or 5,
An electromagnet that exerts a magnetic force on the bar magnet so that the flow rate of the fluid flowing through the flow path becomes a predetermined amount by adjusting the position of the float in the casing to a predetermined position based on the output from the magnetic sensor. A flow meter characterized by comprising. A mass flow controller for adjusting a flow rate of fluid to a predetermined amount,
A cylinder in which one end of the cylindrical shape is a primary side that is a flow path inlet and the other end is a secondary side that is a flow path outlet, and a flow path for flowing fluid along the cylindrical longitudinal direction is formed on the inside. Shaped casing,
A rod-like float that is movably accommodated along the flow channel in the flow channel and incorporates a bar magnet;
A primary magnet attached to the primary side of the casing and exerting a repulsive force on a primary side end of the bar magnet;
A secondary magnet attached to the secondary side of the casing and exerting a repulsive force on the secondary side end of the bar magnet;
A magnetic sensor disposed on a longitudinal extension of the bar magnet of the float housed in the flow path;
A measurement unit that detects a position of the float in the casing based on an output from the magnetic sensor and measures a flow rate of the fluid flowing through the flow path;
An electromagnet that exerts a magnetic force on the bar magnet so that the flow rate of the fluid flowing through the flow path becomes a predetermined amount by adjusting the position of the float in the casing to a predetermined position based on the output from the magnetic sensor;
A mass flow controller comprising:

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