Pulse valve and application device

Abstract

To provide a pulse valve which can apply a fluid to a base material at a desired resolution.SOLUTION: A pulse valve according to one embodiment of the invention includes: a housing portion having a channel in which a fluid containing a supercritical fluid flows; a nozzle plate having a nozzle hole to discharge the fluid flowing through the channel; a needle which is inserted into the housing part and opens or closes the channel; and an orifice which has an opening and abuts on the needle to openably close the channel. The nozzle hole has a laval shape.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a pulse valve and a coating device. [Background technology]

[0002] There is a known paint application technology that replaces VOCs (Volatile Organic Compounds) with a supercritical fluid such as supercritical carbon dioxide during the paint drying process. Patent Document 1 discloses a pulse valve that discharges the supercritical fluid in a gaseous state. Summary of the Invention [Problem to be solved by the invention]

[0003] Pulse valves that eject supercritical fluids spray high-pressure supercritical fluids into low-pressure areas, which causes the fluid to spread out from the nozzle opening, making it difficult to apply the fluid to a substrate with the desired resolution.

[0004] In order to solve the above-mentioned problems, an object of the present invention is to provide a pulse valve and a coating device that can coat a fluid on a substrate with a desired resolution. [Means for solving the problem]

[0005] A pulse valve according to one aspect of the present invention includes a housing portion having a flow path through which a fluid including a supercritical fluid flows, a nozzle plate including a nozzle hole for ejecting the fluid flowing through the flow path, a needle inserted into the housing portion for opening and closing the flow path, and an orifice having an opening and for opening and closing the flow path by abutting with the needle, wherein the nozzle hole is of a Laval shape. [Effects of the Invention]

[0006] According to the present invention, a fluid can be applied to a substrate with a desired resolution. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram illustrating an overall configuration of a coating apparatus according to an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram showing a configuration of a pulse valve according to an embodiment of the present invention. [Figure 3] 1 is a cross-sectional view showing the configuration of a housing portion of a pulse valve according to an embodiment of the present invention. [Figure 4] FIG. 2 is a cross-sectional view showing the configuration of a nozzle plate of a pulse valve according to one embodiment of the present invention. [Figure 5] FIG. 2 is a partial cross-sectional view showing the shape of a nozzle hole of a pulse valve according to one embodiment of the present invention. [Figure 6] 10A and 10B are diagrams showing examples of design of the shape of a nozzle hole of a pulse valve according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes the preferred embodiments of the present invention with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals, and redundant explanations may be omitted.

[0009] FIG. 1 is a schematic diagram showing the overall configuration of a coating apparatus 1 according to one embodiment of the present invention. The coating apparatus 1 includes a generator 30 that generates supercritical carbon dioxide and a high-pressure vessel 6 that mixes the supercritical carbon dioxide generated in the generator 30 with a resin to obtain a fluid mixture of the two. The coating apparatus 1 also includes a pulse valve 10 that discharges the fluid supplied from the high-pressure vessel 6 onto a substrate 12, and a pipe 41 that connects the high-pressure vessel 6 to the pulse valve 10. Note that supercritical carbon dioxide is an example of a "supercritical fluid." Other examples of supercritical fluids include supercritical water and supercritical nitrogen. These supercritical fluids are preferred because they have a low environmental impact and are inexpensive. The fluid mixture of supercritical carbon dioxide and a resin will simply be referred to as a "fluid."

[0010] The resin mixed with supercritical carbon dioxide may be a thermosetting resin or a thermoplastic resin. Examples of thermosetting resins include phenolic resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, silicone resin, polyurethane resin, thermosetting polyimide resin, and thermosetting furan resin. Examples of thermoplastic resins include polyester resin, polyethylene resin, polypropylene resin, acrylonitrile-butadiene-styrene resin, acrylic (PMMA) resin, and polyamide resin.

[0011] A colored coating film may be formed by mixing a dye or pigment into the resin, but in order to avoid the generation of VOCs, it is preferable that the fluid in this embodiment does not contain organic solvents.

[0012] Examples of the substrate 12 onto which the fluid is applied include resin materials, metal materials, and porous materials made of carbon fibers, glass fibers, cellulose fibers, and the like.

[0013] The generation unit 30 of this embodiment includes a cylinder 2 for storing liquid carbon dioxide, a cooler 3 for cooling the liquid carbon dioxide supplied from the cylinder 2 via a high-pressure valve 101 to a temperature below its saturation temperature, and a high-pressure pump 4 for pressurizing the liquid carbon dioxide to a predetermined pressure. The generation unit 30 also includes a heater 5 for heating the liquid carbon dioxide supplied from the high-pressure pump 4 to a predetermined temperature, and a back-pressure valve 102 for returning excess liquid carbon dioxide supplied from the high-pressure pump 4 to a side downstream of the high-pressure pump 4.

[0014] An example of the cooler 3 is a chiller device that circulates cooling water to cool an object to be cooled. An example of the high-pressure pump 4 is a double plunger pump that can control the amount of liquid discharged and prevent pulsation. However, the cooler 3 and the high-pressure pump 4 are not limited to these.

[0015] Liquid carbon dioxide pressurized by a high-pressure pump 4 is heated by a heater 5 to produce supercritical carbon dioxide.

[0016] The high-pressure vessel 6 mixes, under a high-pressure environment, supercritical carbon dioxide supplied from the generation unit 30 via the high-pressure valve 103 with a resin supplied via a route separate from that of the supercritical carbon dioxide. An example of the high-pressure vessel 6 is, but is not limited to, an autoclave.

[0017] The high-pressure vessel 6 has a vessel body 21 that contains supercritical carbon dioxide and resin, a stirring mechanism 22 that stirs the supercritical carbon dioxide and resin introduced into the vessel body 21, and a motor 7 that drives the stirring mechanism 22.

[0018] Examples of the stirring mechanism 22 include a magnetic impeller (an impeller that rotates by the driving force of a motor), a single screw, a twin-screw screw that intermeshes with each other, a twin-screw mixer having a number of intermeshing or overlapping stirring elements, a kneader having intermeshing spiral stirring elements, a static mixer, etc. Preferably, the high-pressure vessel 6 further includes a heater 8 for heating the vessel, and a high-pressure valve 104 for opening the inside of the vessel to the atmosphere.

[0019] A high-pressure valve 105 is provided downstream of the high-pressure vessel 6. When the high-pressure valve 105 opens, the fluid in the high-pressure vessel 6 passes through the pipe 41 and is supplied to the pulse valve 10. It is also preferable to provide a heating mechanism or a heat insulating member around the pipe 41. This makes it possible to maintain the pipe 41 at a predetermined temperature, thereby maintaining the supercritical state of the carbon dioxide flowing through the pipe 41 and increasing its fluidity.

[0020] The pulse valve 10 is connected to the tip of the pipe 41. This allows the pulse valve 10 to communicate with the pipe 41, and the fluid that has flowed through the pipe 41 is introduced into the pulse valve 10. The pulse valve 10 then ejects the introduced fluid onto the substrate 12.

[0021] A fluid having a temperature exceeding 200°C (for example, a temperature of 250°C) and a pressure of approximately 50 MPa to 60 MPa is introduced into the pulse valve 10. The pulse valve 10 discharges the fluid toward the substrate 12 while maintaining the temperature and pressure of the fluid at the time of introduction. The pulse valve 10 also performs high-speed opening and closing operations so that the opening time is, for example, 100 μsec or less. This allows the pulse valve 10 to stably discharge a desired amount of fluid. Details of the pulse valve 10 will be described later in the section <Configuration of Pulse Valve 10>.

[0022] <Operation of Coating Apparatus 1> 1, the fluid discharging operation in the coating device 1 will be described. First, liquid carbon dioxide stored in the cylinder 2 passes through the high-pressure valve 101 and is cooled in the cooler 3 to a temperature below the saturation temperature.

[0023] Subsequently, the supercritical carbon dioxide that has passed through the cooler 3 is introduced into the suction part of the high-pressure pump 4. The liquid carbon dioxide introduced into the high-pressure pump 4 from the suction part is pressurized to a predetermined pressure (for example, 7.3 MPa, which is the critical pressure of carbon dioxide) or higher inside the high-pressure pump 4. During constant-pressure operation, the liquid carbon dioxide introduced into the high-pressure pump 4 is returned to the suction part of the high-pressure pump 4 by the back-pressure valve 102.

[0024] Next, the pressurized liquid carbon dioxide is heated to a predetermined temperature (for example, 31° C., which is the critical temperature of carbon dioxide) or higher by the heater 5. As a result, supercritical carbon dioxide is produced from the liquid carbon dioxide.

[0025] The generated supercritical carbon dioxide is then introduced via a high-pressure valve 103 into a high-pressure vessel 6 that has been heated to a predetermined temperature by a heater 8. The supercritical carbon dioxide is melted and mixed with a resin that has been introduced into the high-pressure vessel 6 via a separate route by a stirring mechanism 22 connected to a motor 7.

[0026] At this time, the fluid is heated to, for example, about 250° C. by the heater 8. Furthermore, the fluid is pressurized to, for example, a pressure of about 50 MPa to 60 MPa by a predetermined pressure-boosting mechanism.

[0027] Next, the high-pressure valve 105 is opened. As a result, the fluid in the high-pressure vessel 6 flows through the pipe 41 toward the pulse valve 10. The pulse valve 10 maintains the temperature and pressure of the introduced fluid while repeatedly opening and closing the valves provided therein, thereby discharging a desired amount of fluid onto the substrate 12.

[0028] <Configuration of pulse valve 10> 2 is a diagram showing the configuration of a pulse valve 10 according to one embodiment of the present invention, in which (a) is a vertical cross-sectional view of the pulse valve 10, and (b) is a perspective cross-sectional view of the pulse valve 10.

[0029] As shown in the figure, the pulse valve 10 of this embodiment has a housing portion 110 having a flow path 112 inside through which a fluid containing a supercritical fluid to be discharged flows, and a nozzle plate 120 attached to the tip side of the housing portion 110 and including a nozzle hole 123 that discharges the fluid flowing through the flow path.

[0030] The pulse valve 10 also has a needle 130 that is inserted into the housing portion 110 and opens and closes the flow path 112 of the housing portion 110, and a drive mechanism 140 that moves the needle 130 back and forth along the central axis (X-axis direction) of the pulse valve 10. The pulse valve 10 also has a heat-insulating flange 150 that is disposed between the housing portion 110 and the drive mechanism 140. The fluid to be discharged in this embodiment is a fluid that is a mixture of supercritical carbon dioxide and resin, but is not limited to this.

[0031] Here, the X direction shown corresponds to the central axis direction of the pulse valve 10. The Y direction corresponds to the width direction of the pulse valve 10. The Z direction corresponds to the height direction of the pulse valve 10.

[0032] <Drive mechanism> The driving mechanism 140 is a mechanical part that is connected to the needle 130 and that moves the needle 130 forward and backward. Specifically, as shown in Fig. 2, the driving mechanism 140 has a long cylindrical extension bar 141 that is connected to the needle 130, and an actuator 142 that moves the extension bar 141 forward and backward.

[0033] The extension bar 141 is preferably made of a material with a low thermal expansion coefficient to avoid thermal expansion due to heat transfer from the needle in contact with the fluid. Examples of materials with a low thermal expansion coefficient include Invar, an alloy of iron and nickel, and Super Invar, an alloy of iron, nickel, and cobalt. Of these, Super Invar, which has an extremely low thermal expansion coefficient, is preferred.

[0034] A fluid having a temperature of, for example, about 250°C flows through the flow channel 112. The tip region of the needle 130 is inserted into the flow channel 112 and comes into contact with the fluid. On the other hand, the extension bar 141 is connected to the needle 130. Therefore, heat from the fluid is transferred to the extension bar 141 via the needle 130. If the extension bar 141 were to undergo significant thermal expansion, the range of advancement and retreat of the extension bar 141 would change, and the range of advancement and retreat of the needle 130 would also change. As a result, it may become impossible to accurately supply a desired amount of the fluid contained in the flow channel 112 to the nozzle plate 120 side.

[0035] In contrast, if the extension bar 141 is made of a material with a low thermal expansion coefficient, such as Super Invar, thermal expansion can be suppressed even if heat from the fluid is transferred from the needle 130. As a result, the desired amount of fluid can be accurately supplied to the nozzle plate 120 side.

[0036] Furthermore, the extension bar 141 is made of a material that can suppress thermal expansion, such as Super Invar material, so that the operational stability of the actuator 142 can be ensured.

[0037] The actuator 142 includes, for example, a piezoelectric element that expands and contracts in response to the application of a pulsed voltage signal. In this embodiment, the actuator 142 expands and contracts in the X direction. The actuator 142 may be a piezoelectric actuator, or may be a ring actuator that is provided around the outer periphery of the extension bar 141. By using a ring actuator for the actuator 142, there are no sharp corners and the load during operation is distributed evenly over the entire surface, thereby improving durability.

[0038] The actuator 142 is preferably selected from the viewpoint of high-speed response to realize valve opening and closing operations of less than approximately 100 μsec, since the actuator 142 is made of a thin piezoelectric element layer and can obtain a large displacement amount at a low voltage.

[0039] <Insulating flange> The insulating flange 150 prevents heat transfer from the housing part 110 to the actuator 142. The material of the insulating flange 150 is not particularly limited, but it is preferably made of ceramics with high thermal insulation properties. By providing the insulating flange 150 between the housing part 110 and the actuator 142, it is possible to prevent heat from being transferred from the fluid to the actuator 142, which is sensitive to heat. As a result, the operational stability of the actuator 142 can be ensured.

[0040] <Housing section> 3 is a cross-sectional view showing the structure of housing portion 110 in pulse valve 10 according to one embodiment of the present invention. Housing portion 110 is located at the forefront of pulse valve 10 and is a housing that contains fluid introduced from piping 41. The tip surface of housing portion 110 (the forefront surface on the +X direction side) faces substrate 12.

[0041] The housing part 110 has a base part 111. A flow path 112 for a fluid to be discharged is formed inside the base part 111. In this embodiment, the flow path 112 is formed along the X direction.

[0042] Furthermore, a hole 113 recessed toward the flow path 112 is provided on the upper surface (positive side in the Y direction) of the housing. A 1 / 8 inch pipe 441 attached to the tip of the pipe 41 is inserted into the hole 113. The 1 / 8 inch pipe 441 inserted into the hole 113 communicates with the flow path 112. However, the pipe 41 communicating with the flow path 112 may be a pipe of a size or shape other than the 1 / 8 inch pipe 441.

[0043] The housing part 110 may be heated by a heating mechanism (for example, a heating block). By providing the heating mechanism, it is possible to prevent the temperature of the fluid flowing through the pipe 41 and the flow path 112 from decreasing.

[0044] The housing part 110 has a nozzle plate 120 on the tip side (positive side in the X direction). The nozzle plate 120 is fastened to the housing part 110 via screws 115a and 115b. The nozzle plate 120 is detachable from the housing part 110.

[0045] The orifice 131 has an opening 131a, and opens and closes the flow path by abutting against the needle 130. The housing part 110 includes a protrusion 111a that fits into a recess 121 of the nozzle plate 120 and abuts against the orifice 131, and the nozzle plate 120 includes a recess 121 that fits the orifice 131. Specifically, the front end side (positive side in the X direction) of the housing part 110 has a protrusion 111a that protrudes toward the nozzle plate 120, and fits into a recess 121 provided on the rear end side (negative side in the X direction) of the nozzle plate 120.

[0046] The pressure of the fluid contained in housing 110 is preferably 60 MPa or less. The temperature of the fluid contained in housing 110 is preferably 250° C. or less, although this is not limitative.

[0047] The housing 110 is preferably made of a metal, such as stainless steel, inconel, or hastelloy, which can improve corrosion resistance to fluids and thermal conductivity through the heating mechanism.

[0048] <Needle> The needle 130 is inserted into the housing portion 110 and functions as a valve that opens and closes the flow path 112 of the housing portion 110 .

[0049] Specifically, as the needle 130 advances, the tip of the needle 130 blocks the opening 131a of the orifice 131 provided between the flow path 112 and the rear end of the nozzle pipe portion 122 of the nozzle plate 120. This closes the flow path 112. Next, as the needle 130 retreats, the tip of the needle 130 moves away from the orifice 131. This opens the opening 131a of the orifice 131, and the flow path 112 opens.

[0050] By opening and closing the flow channel 112 in the needle 130, a desired amount of the fluid that has reached the flow channel 112 can be supplied to the nozzle plate 120. The response speed of the needle 130 (valve opening time) is preferably 100 μsec or less.

[0051] <Nozzle plate> The nozzle plate 120 has nozzle holes 123 drilled in the +X direction. The nozzle holes 123 have a Laval shape, which will be described later, and a flow parallel to the +X direction side is formed, allowing the fluid to be applied to the opposing substrate 12 with the desired resolution.

[0052] The diameter of the nozzle hole 123 is preferably 5 μm or more and 500 μm or less, more preferably 100 μm or more and 300 μm or less, and even more preferably 150 μm or more and 250 μm or less.

[0053] If the diameter of the nozzle holes 123 is less than 5 μm, the small diameter may hinder stable ejection of the fluid. Also, if the diameter of the nozzle holes 123 is more than 500 μm, the thickness of the nozzle plate 120 in the area excluding the nozzle holes 123 becomes too thin, and there is a possibility that it may not be able to withstand the pressure when ejecting the fluid.

[0054] The nozzle plate 120 is preferably made of metal, such as stainless steel, inconel, or hastelloy, which improves corrosion resistance to fluids and thermal conductivity through the heating mechanism, and ensures strength.

[0055] The nozzle plate 120 may be heated by a heating mechanism. By providing a heating mechanism, it is possible to prevent the temperature of the fluid flowing through the nozzle holes 123 from decreasing.

[0056] <Orifice> The orifice 131 has a disk shape formed on the YZ plane and includes an opening 131a drilled in the X direction. The outer diameter portion of the orifice 131 is fitted into the inner diameter portion of the recess 121 of the nozzle plate 120. An inclined portion 131b is provided at the corner on the tip side of the orifice 131, and the tip side of the orifice 131 abuts against the recess 121 of the nozzle plate 120. The material of the orifice 131 can be suitably selected from resin, metal, ceramics, etc. depending on the pressure and temperature of the fluid.

[0057] The protrusion 111a of the housing part 110 and the outer diameter part of the orifice 131 are fitted into the recess 121 of the nozzle plate 120, and the housing part 110 and the nozzle plate 120 are fastened together by screws 115a and 115b, sandwiching the orifice 131 therebetween.

[0058] This structure can prevent the fluid from leaking to the outside even when the fluid pressure is high. Also, by providing the orifice 131 between the needle 130 and the nozzle plate 120, the needle 130 and the nozzle plate 120 do not come into direct contact with each other, which can prevent deterioration of the nozzle plate 120. Furthermore, when attaching or detaching the nozzle plate 120, misalignment between the nozzle hole 123, the opening 131a of the orifice 131, and the housing part 110 can be prevented.

[0059] <Shape of the nozzle hole 123 of the pulse valve 10> Figure 5 is a partial cross-sectional view showing the shape of nozzle hole 123 of pulse valve 10 according to one embodiment of the present invention. In Figure 5, the axis corresponding to the central axis of nozzle hole 123 is set as the X axis, and the axis perpendicular to the central axis of nozzle hole 123 at the throat of nozzle hole 123 is set as the Y axis. The distance from the throat of nozzle hole 123 is set as x, and the distance perpendicular to the central axis of nozzle hole 123 is set as y, with the value of x at the throat of nozzle hole 123 being 0 and the value of y at the central axis of nozzle hole 123 being 0.

[0060] The shape of the nozzle hole 123 is symmetrical about the central axis of the nozzle hole 123 and includes an inflection point P1 in a cross section including the central axis of the nozzle hole 123. A first region R1 is defined as the region from the throat to the inflection point P1, and the first region R1 has a convex shape toward the central axis of the nozzle hole 123. A second region R2 is defined as the region from the inflection point P1 to the discharge port, and the second region R2 has a convex shape toward the opposite side of the central axis of the nozzle hole 123.

[0061] The shape of the nozzle hole 123 is a Laval shape based on the cross-sectional area of ​​the discharge port and the pressure of the fluid at the inlet. Therefore, by narrowing the flow of fluid from the inlet at the throat to make the flow velocity faster than the speed of sound, and by gently expanding the expansion wave of the fluid generated in the first region R1 in the second region R2, a supersonic flow parallel to the central axis of the nozzle hole 123 can be formed from the discharge port.

[0062] <Design Method of Nozzle Hole 123 of Pulse Valve 10> The following describes a method for designing the shape of the nozzle hole 123. The shape of the nozzle hole 123 in this embodiment is designed in accordance with the pressure and temperature of the fluid and the desired resolution.

[0063] The method for designing the shape of the nozzle hole 123 includes the steps of calculating a cross-sectional area at the outlet of the nozzle hole 123, and calculating a flow velocity of the fluid at the outlet of the nozzle hole 123 based on the pressure condition and specific heat ratio at the inlet of the nozzle hole 123. The method for designing the shape of the nozzle hole 123 also includes the steps of calculating a throat cross-sectional area of ​​the nozzle hole 123, calculating the shape of the nozzle hole 123 in the first region R1, and calculating the shape of the nozzle hole 123 in the second region R2.

[0064] First, we will explain the step of calculating the cross-sectional area of ​​the outlet of the nozzle hole 123. The pulse valve 10 according to this embodiment ejects a fluid containing a supercritical fluid and applies it onto the substrate 12 with the desired resolution. Therefore, it is preferable that the cross-sectional area At of the outlet of the nozzle hole 123 is a desired value.

[0065] Next, a description will be given of a step of calculating the flow velocity of the fluid at the outlet of the nozzle hole 123 based on the pressure condition and specific heat ratio at the inlet of the nozzle hole 123. The pressure condition at the inlet may be the inlet pressure. The flow velocity may be the Mach number.

[0066] Discharge port x of nozzle hole 123 = x t Mach number M of fluid flow velocity at t When expressed as a one-dimensional entropy flow equation, it is as shown in the following equation (1). о is the inlet pressure (Pa), p t is the outlet pressure (Pa), and γ is the specific heat ratio, which is expressed as equation (2).

[0067]

number

[0068] In equation (2), c p is the specific heat at constant pressure, c v is the specific heat at constant volume, and these are expressed as the following equations (3) to (5). Equations (3) to (5) are based on the thermodynamic equation of state described in Roland Span and Wolfgang Wagner, "A New Equation of State for Carbon Dioxide Covering the Fluid Region from the Triple-Point Temperature to 1100 K at Pressures up to 800 MPa," Journal of Physical and Chemical Reference Data 25, 1509 (1996). Here, ρ is the density, ρ c is the critical density, T is the temperature, T c is the critical temperature, and δ and τ are variables.

[0069]

number

[0070] Next, a step of calculating the throat cross-sectional area of ​​the nozzle hole 123 will be described. * Then, based on J. Conrad Crown, "Supersonic Nozzle Design" NACA Technical Note No. 1651, it can be expressed as the following equation (6).

[0071]

number

[0072] Next, the step of calculating the shape of the nozzle hole 123 in the first region R1 will be described. Assuming that the streamline at the throat (x=0) in FIG. 5 is parallel to the x-axis and that the streamline passing through the inflection point P1(x1, y1) traces a radial line centered on an arbitrary point, y1 in the first region R1 can be geometrically obtained by the following equation (7): where y0 is the vertical distance from the central axis of the valve at the throat, and θ1 is the angle between the tangent to the inflection point P1(x1, y1) and the central axis of the nozzle hole 123.

[0073]

number

[0074] Also, A1 / A * is expressed as equation (8) based on the relationship between the Mach number and cross-sectional area of ​​the entropy flow.

[0075]

number

[0076] Furthermore, the Mach number M1 at the inflection point P1(x1, y1) is expressed by the implicit numerical method as shown in equation (9).

[0077]

number

[0078] In equation (9), v is expressed by the following equation (10) based on the Brandt-Meyer function.

[0079]

number

[0080] In the first region R1, if the shape of the nozzle hole 123 in the first region R1 is assumed to be a cubic curve, the value of x1 is expressed by the following equation (11).

[0081]

number

[0082] Substituting x1 and y1 into equation (11) and rearranging with respect to x1, we obtain the following equation (12).

[0083]

number

[0084] As described above, by changing the value of x from 0 to x1, the shape of the nozzle hole 123 in the first region R1 can be calculated.

[0085] Finally, a step of determining the shape of the nozzle hole 123 in the second region R2 will be described. In the first region R1, point P2, which intersects with Mach line L1 starting from inflection point P1, has vector r starting from the same origin as r1 and angle θ.

[0086] In this case, θ is the angle between the streamline and the central axis of nozzle hole 123, and variable r is the distance from the intersection of the tangent to inflection point P1 and the central axis of nozzle hole 123 to the intersection of the streamline and Mach line L1. Then, the point where Mach line L2 starting from point P2 intersects with nozzle hole 123 is defined as Q, the point where an arc of radius r that passes through point P2 intersects with nozzle hole 123 is defined as P', the point from point Q that is perpendicular to the streamline that passes through point P2 is defined as Q', and the distance between point P2 and point Q is defined as 1.

[0087] That is, the variable l is the length of the Mach line L2. The variable α is the angle between the Mach line L2, which is a straight line connecting the intersection of the streamline and the Mach line L1 to the intersection of the streamline and the perpendicular to the surface of the nozzle hole 123. At this time, the following equation (13) is obtained based on the equation of continuity and the geometric relational equation.

[0088]

number

[0089] When formula (13) is rearranged with respect to the distance l between point P2 and point Q, the following formula (14) is obtained: Formulas (15) to (18) represent the formulas for each parameter in formula (14).

[0090]

number

[0091] From the above, the following equations (19) and (20) are obtained.

[0092]

number

[0093] Mach number M is calculated from M1 to M t By changing the value of the angle .theta.

[0094] <Design example of the nozzle hole 123 of the pulse valve 10> 6 is a diagram showing a design example of the shape of the nozzle hole 123 of the pulse valve 10 according to one embodiment of the present invention. The example shown is an example designed based on the steps described above in <Method for designing the nozzle hole 123 of the pulse valve 10>.

[0095] 6 shows the case where the inlet pressure is changed from 10 MPa to 50 MPa when a fluid, which is carbon dioxide at a temperature of 120°C, is discharged from the nozzle hole 123. In FIG. 6, (a) shows the case where the diameter of the discharge port cross section as the desired resolution of the nozzle hole 123 is 100 μm, (b) shows 50 μm, and (c) shows 200 μm.

[0096] In Figure 6, as in Figure 5, the axis corresponding to the central axis of the nozzle hole 123 is the X-axis, the axis perpendicular to the central axis of the nozzle hole 123 at the throat of the nozzle hole 123 is the Y-axis, and the value of y on the central axis of the nozzle hole 123 is y=0.

[0097] As shown in the illustrated example, the pulse valve 10 according to this embodiment can form a nozzle plate 120 having a suitable nozzle hole 123 shape depending on the fluid to be ejected, the temperature, the pressure, and the desired resolution.

[0098] <Action and effect> The shape of the nozzle hole 123 in the pulse valve 10 according to this embodiment is a Laval shape based on the cross-sectional area of ​​the discharge port and the pressure of the fluid at the inlet. Therefore, by narrowing the flow of fluid from the inlet at the throat to a flow velocity faster than the speed of sound, and by gently expanding the expansion wave of the fluid generated in the first region R1 in the second region R2, a supersonic flow parallel to the central axis of the nozzle hole 123 can be formed from the discharge port. Therefore, the pulse valve 10 according to this embodiment can apply the fluid to the substrate 12 with the desired resolution.

[0099] Furthermore, in the pulse valve 10 according to this embodiment, the convex portion 111a of the housing portion 110 and the outer diameter portion of the orifice 131 are fitted into the concave portion 121 of the nozzle plate 120, and the housing portion 110 and the nozzle plate 120 are fastened together with the orifice 131 sandwiched between them. Therefore, the pulse valve 10 utilizes the shape of the nozzle hole 123 and has a structure that can withstand high-pressure fluids.

[0100] Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and various modifications and improvements are possible within the scope of the present invention.

[0101] For example, aspects of the present invention are as follows. <1> a housing portion having a flow path through which a fluid including a supercritical fluid flows; a nozzle plate including nozzle holes for discharging the fluid flowing through the flow path; a needle inserted into the housing portion to open and close the flow path; an orifice having an opening and configured to open and close the flow path by contacting the needle; Including, The nozzle hole is a Laval shape. Pulse valve. <2> the shape of the nozzle hole is symmetrical with respect to a central axis of the nozzle hole, and includes an inflection point in a cross section including the central axis of the nozzle hole, and a first region from a throat to the inflection point has a convex shape toward the central axis of the nozzle hole, and a second region from the inflection point to a discharge outlet has a convex shape toward the opposite side to the central axis of the nozzle hole. The shape is based on the cross-sectional area of ​​the outlet and the pressure of the fluid at the inlet. The aforementioned <1> The pulse valve according to claim 1. <3> The shape of the nozzle hole is expressed as follows, where x is the distance of the nozzle hole from the throat and y is the distance in the vertical direction from the central axis of the nozzle hole: In the first region, the following formula (i) is expressed: In the second region, the following formula (ii) and formula (iii) are represented: The aforementioned <2> where y0 is the vertical distance from the central axis of the nozzle hole in the throat, θ is the angle between the streamline and the central axis of the nozzle hole, θ1 is the angle between the tangent to the inflection point and the central axis of the nozzle hole, coordinates (x1, y1) are x and y coordinates at the inflection point, and r, α, and l are variables.

number

[0102] 1 Coating device 10 Pulse valve 110 Housing section 112 Channel 120 nozzle plate 123 Nozzle hole 130 Needle 131 Orifice 131a opening 140 Drive Mechanism 142 Actuator 150 Insulation flange P1 inflection point R1 1st area R2 2nd area [Prior art documents] [Patent documents]

[0103] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-30669

Claims

1. a housing portion having a flow path through which a fluid including a supercritical fluid flows; a nozzle plate including nozzle holes for discharging the fluid flowing through the flow path; a needle inserted into the housing portion to open and close the flow path; an orifice having an opening and configured to open and close the flow path by contacting the needle; Including, The nozzle hole is a Laval shape. Pulse valve.

2. the shape of the nozzle hole is symmetrical with respect to a central axis of the nozzle hole, and includes an inflection point in a cross section including the central axis of the nozzle hole, and a first region from a throat to the inflection point has a convex shape toward the central axis of the nozzle hole, and a second region from the inflection point to a discharge port has a convex shape toward the opposite side to the central axis of the nozzle hole. The shape is based on the cross-sectional area of ​​the outlet and the pressure of the fluid at the inlet. The pulse valve according to claim 1 .

3. The shape of the nozzle hole is expressed as follows, where x is the distance of the nozzle hole from the throat and y is the distance in the vertical direction from the central axis of the nozzle hole: In the first region, the following formula (i) is expressed: In the second region, the following formula (ii) and formula (iii) are represented: The pulse valve according to claim 2 . However, y ０ is the vertical distance from the central axis of the nozzle hole at the throat, θ is the angle between the streamline and the central axis of the nozzle hole, and θ １ is the angle between the tangent to the inflection point and the central axis of the nozzle hole, and the coordinate (x １ , y １ ) are the x and y coordinates at the inflection point, and r, α, and l are variables. [Equation 1]

4. the housing portion includes a protrusion that fits into a recess of the nozzle plate and abuts against the orifice, the nozzle plate includes a recess that fits over the orifice; The pulse valve according to claim 1 .

5. The nozzle plate is detachable from the housing portion. The pulse valve according to claim 1 .

6. a drive mechanism that moves the needle back and forth in the central axis direction of the pulse valve; The drive mechanism includes: an extension bar connected to the needle and made of Super Invar material; an actuator that moves the extension bar forward and backward; Including, The pulse valve according to claim 1 .

7. The actuator is a piezoelectric actuator. The pulse valve according to claim 6.

8. The piezoelectric actuator is a ring actuator. The pulse valve according to claim 7.

9. an insulating flange disposed between the housing portion and the drive mechanism; The pulse valve according to claim 6.

10. A pulse valve according to any one of claims 1 to 9, Coating equipment.

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