Pulse valve and coating apparatus

Abstract

A pulse valve includes a housing portion having a passage through which a fluid containing a supercritical fluid flows, a nozzle plate having a Laval-shaped nozzle hole to discharge the fluid flowing through the passage in a direction of a central axis of the nozzle hole, an orifice having an opening communicating with the passage, the orifice being disposed between the housing portion and the nozzle plate in the direction of the central axis, and a valve needle inserted into the housing portion to abut on the opening of the orifice to openably close the passage.

Description

Technical Field

[0001] This embodiment relates to a pulse valve and a coating device. Background Technology

[0002] A technique for applying a coating material during a coating material drying process is known, in which volatile organic compounds (VOCs) are replaced with a supercritical fluid such as supercritical carbon dioxide. Patent Document 1 discloses a pulse valve for discharging the supercritical fluid in a gaseous state. Summary of the Invention

[0003] [Technical Issues]

[0004] The pulse valve discharging the supercritical fluid injects high-pressure supercritical fluid into a low-pressure section, causing the fluid to diffuse from the nozzle opening. Therefore, it is difficult to apply the fluid to the base material with the desired resolution.

[0005] To address the aforementioned problems, the objective of this embodiment is to provide a pulse valve and a coating apparatus capable of applying fluid to a base material with a desired resolution.

[0006] [Solution to the problem]

[0007] In one aspect of this disclosure, a pulse valve is provided, comprising: a housing portion having a channel for allowing a fluid containing a supercritical fluid to flow through the channel; a nozzle plate having a Laval-shaped nozzle orifice for discharging fluid flowing through the channel in a central axial direction of the nozzle orifice; an orifice having an opening communicating with the channel, the orifice being disposed between the housing portion and the nozzle plate in the central axial direction; and a valve needle inserted into the housing portion to engage with the opening of the orifice, thereby openably closing the channel.

[0008] [Beneficial effects of the invention]

[0009] According to this embodiment, fluid can be applied to a base material with the desired resolution. Attached Figure Description

[0010] A more complete understanding of the embodiments of this disclosure and its many accompanying advantages and features can be readily obtained and understood from the following detailed description with reference to the accompanying drawings.

[0011] [ Figure 1 ]

[0012] Figure 1 This is a schematic diagram showing the overall configuration of the coating apparatus.

[0013] [ Figure 2A and 2B ]

[0014] Figure 2A and 2B This is a view showing the configuration of the pulse valve.

[0015] [ Figure 3 ]

[0016] Figure 3 This is a cross-sectional view showing the configuration of the housing portion in the pulse valve.

[0017] [ Figure 4 ]

[0018] Figure 4 This is a cross-sectional view showing the configuration of the nozzle plate of the pulse valve.

[0019] [ Figure 5 ]

[0020] Figure 5 This is a partial cross-sectional view showing the shape of the nozzle orifice of the pulse valve.

[0021] [ Figures 6A to 6C ]

[0022] Figures 6A to 6C This is a view showing a design example of the shape of the nozzle orifice of a pulse valve.

[0023] The accompanying drawings are intended to depict embodiments of this disclosure and should not be construed as limiting its scope. Unless explicitly stated otherwise, the drawings are not considered to be drawn to scale. Furthermore, in several views, the same or similar reference numerals denote the same or similar parts. Detailed Implementation

[0024] In describing the embodiments shown in the accompanying drawings, specific terminology has been used for clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology chosen so far, and it should be understood that each particular element includes all technical equivalents that have similar functionality, operate in a similar manner, and achieve similar results.

[0025] Embodiments of this disclosure are now described with reference to the accompanying drawings. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0026] Hereinafter, the embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the drawings, the same parts are indicated by the same reference numerals, and repeated descriptions are omitted.

[0027] Figure 1This is a schematic diagram showing the overall configuration of the coating apparatus 1. The coating apparatus 1 includes a generating section 30 for generating supercritical carbon dioxide and a high-pressure vessel 6 for mixing the supercritical carbon dioxide generated by the generating section 30 with a resin to obtain a fluid as a mixture of the two. Additionally, the coating apparatus 1 includes a pulse valve 10 for discharging the fluid supplied from the high-pressure vessel 6 to a base material 12; and a pipe 41 connecting the high-pressure vessel 6 to the pulse valve 10. 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 due to their low environmental impact and low cost. The fluid, which is a mixture of supercritical carbon dioxide and resin, is simply referred to as "fluid".

[0028] The resin mixed with supercritical carbon dioxide can be a thermosetting resin or a thermoplastic resin. Examples of thermosetting resins include phenolic resins, epoxy resins, melamine resins, urea resins, unsaturated polyester resins, silicone resins, polyurethane resins, thermosetting polyimide resins, and thermosetting furan resins. Examples of thermoplastic resins include polyester resins, polyethylene resins, polypropylene resins, acrylonitrile-butadiene-styrene resins, acrylic (PMMA) resins, and polyamide resins.

[0029] Colored coating films can be formed by mixing dyes and pigments with resins. However, to avoid the generation of VOCs, the fluid in this embodiment is preferably free of organic solvents.

[0030] The base material 12 to which the fluid is applied includes resin materials, metal materials, porous materials formed by carbon fibers, glass fibers, cellulose fibers, etc.

[0031] The generating section 30 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 saturation temperature or lower, and a high-pressure pump 4 for pressurizing the liquid carbon dioxide to a predetermined pressure. The generating section 30 also includes a heater 5 that heats the liquid carbon dioxide supplied from the high-pressure pump 4 to a predetermined temperature, and a back pressure valve 102 that returns any remaining liquid carbon dioxide from the high-pressure pump 4 to the downstream side of the high-pressure pump 4.

[0032] Examples of coolers 3 include refrigerant devices that cool the object being cooled by circulating cooling water. Examples of high-pressure pumps 4 include dual-plunger pumps capable of controlling the fluid discharge rate and preventing pulsation. However, coolers 3 and high-pressure pumps 4 are not limited to these.

[0033] Supercritical carbon dioxide is generated by heating liquid carbon dioxide pressurized by a high-pressure pump 4 using a heater 5.

[0034] High-pressure vessel 6 mixes supercritical carbon dioxide supplied from generation section 30 via high-pressure valve 103 and resin supplied via a different path than that of supercritical carbon dioxide under high-pressure conditions. An example of high-pressure vessel 6 is a high-pressure reactor. However, it is not limited to this.

[0035] The high-pressure vessel 6 includes: a vessel body 21 containing supercritical carbon dioxide and resin; a stirring mechanism 22 for stirring the supercritical carbon dioxide and resin introduced into the vessel body 21; and a motor 7 for driving the stirring mechanism 22.

[0036] Examples of stirring mechanisms 22 include magnetic impellers (impellers that rotate by driving force from a motor), single screws, intermeshing twin screws, twin-screw mixers with a large number of intermeshing or overlapping stirring elements, kneaders with intermeshing helical stirring elements, static mixers, etc. The high-pressure vessel 6 preferably also includes a heater 8 for heating the vessel and a high-pressure valve 104 for opening the interior of the vessel to the atmosphere.

[0037] A high-pressure valve 105 is provided downstream of the high-pressure vessel 6. When the high-pressure valve 105 is opened, fluid in the high-pressure vessel 6 is supplied to the pulse valve 10 through the pipe 41. A heating mechanism or heat insulation component is preferably provided around the pipe 41. This allows the pipe 41 to be maintained at a predetermined temperature, and thereby maintains the supercritical state of the carbon dioxide flowing through the pipe 41, improving its fluidity.

[0038] Pulse valve 10 is connected to the end of pipe 41. Thus, pulse valve 10 and pipe 41 are in communication, and fluid flowing through pipe 41 is introduced into pulse valve 10. Pulse valve 10 discharges the introduced fluid to base material 12.

[0039] For example, a fluid with a temperature exceeding 200 °C (e.g., 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 base material 12 while maintaining the temperature and pressure at which the fluid was introduced. The pulse valve 10 performs a high-speed opening / closing operation, such that the opening time is, for example, 100 μs or less. Thus, the pulse valve 10 stably discharges the desired amount of fluid. Details regarding the pulse valve 10 will be described in the section on "Configuration of the Pulse Valve 10" described later.

[0040] <Operation of Coating Device 1>

[0041] Reference Figure 1 The discharge operation of the fluid in the coating apparatus 1 is described below. First, the liquid carbon dioxide stored in the gas cylinder 2 is cooled to the saturation temperature or lower by the cooler 3 via the high-pressure valve 101.

[0042] Subsequently, the supercritical carbon dioxide that has passed through cooler 3 is introduced into the suction section of high-pressure pump 4. The liquid carbon dioxide introduced from the suction section into high-pressure pump 4 is pressurized in high-pressure pump 4 to a predetermined pressure (e.g., 7.3 MPa, which is the critical pressure of carbon dioxide) or higher.

[0043] During constant pressure operation, the liquid carbon dioxide introduced into the high-pressure pump 4 is returned to the suction section of the high-pressure pump 4 through the back pressure valve 102.

[0044] Subsequently, the pressurized fluid carbon dioxide is heated to a predetermined temperature (e.g., 31 °C, which is the critical temperature of carbon dioxide) or higher by heater 5. This generates supercritical carbon dioxide from liquid carbon dioxide.

[0045] Subsequently, the generated supercritical carbon dioxide is introduced into a high-pressure vessel 6 heated to a predetermined temperature by heater 8 via high-pressure valve 103. The supercritical carbon dioxide melts and is mixed with resin introduced into the high-pressure vessel 6 via a stirring mechanism 22 connected to motor 7.

[0046] At this point, the fluid is heated by heater 8 to, for example, about 250 °C. The fluid is then pressurized by a predetermined pressurization mechanism to, for example, a pressure of about 50 MPa to 60 MPa.

[0047] Subsequently, the high-pressure valve 105 is opened. As a result, fluid within the high-pressure vessel 6 flows through pipe 41 to the pulse valve 10. While maintaining the temperature and pressure of the introduced fluid, the pulse valve 10 repeatedly opens and closes to discharge the required amount of fluid to the base material 12.

[0048] <Configuration of Pulse Valve 10>

[0049] Figure 2A and 2B This is a view showing the configuration of the pulse valve 10. Figure 2A This is a longitudinal cross-sectional view of pulse valve 10. Figure 2B This is a perspective cross-sectional view of the pulse valve 10.

[0050] As shown, the pulse valve 10 includes: a housing portion 110 having a channel 112 in which a supercritical fluid to be discharged flows internally; and a nozzle plate 120 attached to the distal side of the housing portion 110 and having a nozzle orifice 123 for discharging the fluid flowing in the channel.

[0051] The pulse valve 10 includes: a valve needle 130 inserted into a housing portion 110 to open and close a passage 112 of the housing portion 110; and a drive mechanism 140 for advancing and retracting the valve needle 130 along the central axis (X-axis) of the pulse valve 10. The pulse valve 10 includes a heat-insulating flange 150 disposed between the housing portion 110 and the drive mechanism 140. In this embodiment, the fluid to be discharged is a mixture of supercritical carbon dioxide and resin, but is not limited thereto.

[0052] Here, the X direction in the diagram corresponds to the direction of the central axis 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.

[0053] <Drive mechanism>

[0054] The drive mechanism 140 is a component connected to the valve needle 130 and that enables the valve needle 130 to advance and retract. Specifically, as shown... Figure 2A and 2B As shown, the drive mechanism 140 includes an elongated tubular extension rod 141 connected to the valve needle 130, and an actuator 142 that moves the extension rod 141 forward and backward.

[0055] The extension rod 141 is preferably made of a material with low thermal expansion efficiency to avoid thermal expansion due to heat transfer from the valve needle in contact with the fluid. Examples of materials with low thermal expansion coefficients include invar materials, which are alloys of iron and nickel, and super invar materials, which are alloys of iron, nickel, and cobalt. Among these, super invar alloy materials with extremely low thermal expansion efficiency are suitable.

[0056] A fluid with a temperature of, for example, approximately 250 °C flows through channel 112. The distal region of valve needle 130 is inserted into channel 112 and comes into contact with the fluid. Meanwhile, extension rod 141 is connected to valve needle 130. Heat from the fluid is transferred to extension rod 141 via valve needle 130. If extension rod 141 undergoes significant thermal expansion, the range of advance and retraction of valve needle 130 will also change as the range of advance and retraction of extension rod 141 changes. As a result, it may be impossible to accurately supply the desired amount of fluid contained in channel 112 to the nozzle plate 120 side.

[0057] On the other hand, since the extension rod 141 is made of a material with low thermal expansion efficiency (e.g., superinvar material), thermal expansion can be suppressed even when heat of the fluid is transferred from the valve needle 130. As a result, the desired amount of fluid can be accurately supplied to the nozzle plate 120 side.

[0058] Since the extension rod 141 is made of a material that can suppress thermal expansion, such as super Invar material, the operational stability of the actuator 142 can be ensured.

[0059] Actuator 142 includes, for example, a piezoelectric element that expands and contracts in response to the application of a pulse voltage signal. Actuator 142 expands and contracts in the X direction.

[0060] The actuator 142 can be a piezoelectric actuator or a ring actuator circumferentially disposed on the outer periphery of the extension rod 141. When the actuator 142 is a ring actuator, there are no sharp angle portions, and the load during operation is evenly distributed across the entire surface, thereby enhancing durability.

[0061] Because actuator 142 comprises a thin layer of piezoelectric elements, a large displacement can be achieved at low voltages. Actuator 142 is preferably selected based on fast response to achieve valve opening / closing operation in less than about 100 μs.

[0062] <Insulating flange>

[0063] The heat-insulating flange 150 prevents heat transfer from the housing portion 110 to the actuator 142 side. The material of the heat-insulating flange 150 is not particularly limited, but it is preferably made of ceramic with high heat insulation properties. By providing the heat-insulating flange 150 between the housing portion 110 and the actuator 142, heat transfer from the fluid to the heat-sensitive actuator 142 can be suppressed. As a result, the operational stability of the actuator 142 can be ensured.

[0064] <Shell Section>

[0065] Figure 3 This is a cross-sectional view showing the structure of the housing portion 110 in the pulse valve 10. The housing portion 110 is the foremost part of the pulse valve 10 and is a case that houses the fluid introduced from the pipe 41. The distal surface of the housing portion 110 (the foremost surface on the + side in the X direction) faces the base material 12.

[0066] The housing portion 110 has a base portion 111. A channel 112 for the fluid to be discharged is formed inside the base portion 111. The channel 112 is formed along the X direction.

[0067] A recessed portion 113 facing the channel 112 is provided on the upper surface of the housing (Y direction, + side). A 1 / 8-inch tube 441 attached to the distal end of the tube 41 is inserted into the recessed portion 113. The 1 / 8-inch tube 441 inserted into the recessed portion 113 communicates with the channel 112. However, the tube 41 communicating with the channel 112 may be a conduit having a different size or shape than the 1 / 8-inch tube 441.

[0068] The housing portion 110 can be heated by a heating mechanism (e.g., a heating block). By providing a heating mechanism, it is possible to prevent the temperature of the fluid flowing through the pipe 41 and the channel 112 from dropping.

[0069] The housing portion 110 has a nozzle plate 120 on its distal side (+ side in the X direction). The nozzle plate 120 is fastened to the housing portion 110 by screws 115a, 115b. The nozzle plate 120 can be attached to the housing portion 110 and can be detached from the housing portion 110.

[0070] The orifice 131 has an opening 131a and is adjacent to the valve needle 130 to open and close the passage. The housing portion 110 includes a recess 121 that engages with the nozzle plate 120 and a protrusion 111a that is adjacent to the orifice 131. The nozzle plate 120 includes a recess 121 that engages with the orifice 131. Specifically, a protrusion 111a is provided on the distal side (+ side in the X direction) of the housing portion 110, protruding toward the nozzle plate 120, and this protrusion 111a engages with the recess 121 provided on the rear end side (- side in the X direction) of the nozzle plate 120.

[0071] The pressure of the fluid contained in the housing portion 110 is preferably 60 MPa or lower. The temperature of the fluid contained in the housing portion 110 is preferably 250 °C or lower. However, it is not limited thereto.

[0072] The preferred materials for the housing portion 110 are metals, stainless steel, Inconel, Hastelloy, etc. This results in improved corrosion resistance of the fluid and improved thermal conductivity of the heating mechanism.

[0073] <Valve needle>

[0074] The valve needle 130 is inserted into the housing portion 110 and serves as a valve for opening and closing the passage 112 of the housing portion 110.

[0075] Specifically, when the valve needle 130 advances, its distal end closes the opening 131a of the orifice 131 located between the channel 112 and the rear end of the nozzle tube portion 122 of the nozzle plate 120. As a result, the channel 112 is closed. Subsequently, when the valve needle 130 retracts, its distal end separates from the orifice 131. As a result, the opening 131a of the orifice 131 opens, and the channel 112 opens.

[0076] By opening / closing the channel 112 via the valve needle 130, a desired amount of fluid arriving at the channel 112 can be supplied to the nozzle plate 120 side. The response speed (valve opening time) of the valve needle 130 is preferably 100 μs or less.

[0077] <Nozzle Plate>

[0078] The nozzle plate 120 has a nozzle hole 123 drilled in the +X direction. The nozzle hole 123 has a Laval shape as described below, forming a flow parallel to the + side in the X direction, which enables the coating fluid to be applied to the opposing base material 12 with the desired resolution.

[0079] The diameter of the nozzle orifice 123 is preferably 5 μm or more and 500 μm or less. More preferably, the diameter of the nozzle orifice 123 is 100 μm or more and 300 μm or less, and even more preferably 150 μm or more and 250 μm or less.

[0080] When the diameter of the nozzle orifice 123 is less than 5 μm, the small diameter may hinder the stable discharge of fluid. When the diameter of the nozzle orifice 123 exceeds 500 μm, the thickness of the area in the nozzle plate 120 other than the nozzle orifice 123 becomes thinner, which may not be able to withstand the pressure when the fluid is discharged.

[0081] The preferred materials for the nozzle plate 120 are metals, stainless steel, chromium-nickel-iron alloys, Hastelloy, etc. This improves the corrosion resistance of the fluid and the thermal conductivity of the heating mechanism, while ensuring strength.

[0082] The nozzle plate 120 can be heated by a heating mechanism. By providing a heating mechanism, the temperature of the fluid flowing through the nozzle orifice 123 can be prevented from decreasing.

[0083] <Koukou>

[0084] The orifice 131 has a disk shape arranged in 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 of the distal end of the orifice 131, and the distal end of the orifice 131 abuts against the recess 121 of the nozzle plate 120. As the material for the orifice 131, resin, metal, ceramic, etc., can be appropriately used depending on the pressure and temperature of the fluid.

[0085] The protrusion 111a of the housing portion 110 and the outer diameter portion of the orifice 131 fit into the recess 121 of the nozzle plate 120. The housing portion 110 and the nozzle plate 120 are fastened by clamping the orifice 131 with screws 115a and 115b.

[0086] With this structure, fluid leakage to the outside can be suppressed even under high fluid pressure. Since the orifice 131 is located between the valve needle 130 and the nozzle plate 120, the valve needle 130 and the nozzle plate 120 do not directly contact each other, thereby suppressing the deterioration of the nozzle plate 120.

[0087] When attaching or removing the nozzle plate 120, misalignment between the nozzle hole 123, the opening 131a of the orifice 131, and the housing portion 110 can be prevented.

[0088] <Shape of the nozzle orifice 123 of the pulse valve 10>

[0089] Figure 5 This is a partial cross-sectional view showing the shape of the nozzle orifice 123 of the pulse valve 10. Figure 5 In this diagram, the axis corresponding to the central axis of the nozzle orifice 123 is defined as the X-axis, and the axis perpendicular to the central axis of the nozzle orifice 123 at the throat of the nozzle orifice 123 is defined as the Y-axis. The distance from the throat of the nozzle orifice 123 is x, and the lateral distance from the central axis of the nozzle orifice 123 is y. The value of x at the throat of the nozzle orifice 123 is 0, and the value of y at the central axis of the nozzle orifice 123 is 0.

[0090] The shape of the nozzle orifice 123 is linearly symmetrical with respect to its central axis, and includes an inflection point P1 in the cross-section encompassing the central axis of the nozzle orifice 123. A first region R1 extends from the throat to the inflection point P1, and has a protruding shape facing the side opposite to the central axis of the nozzle orifice 123. A second region R2 extends from the inflection point P1 to the discharge port, and has a protruding shape facing the side opposite to the central axis of the nozzle orifice 123.

[0091] The shape of the nozzle orifice 123 is a Laval shape based on the cross-sectional area of ​​the discharge port and the pressure of the fluid at the inflow port. Therefore, by contracting the flow of fluid from the inflow port at the throat to make the flow velocity equal to or higher than the speed of sound and slowly 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 orifice 123 can be formed from the discharge port.

[0092] <Method for designing the nozzle orifice 123 of the pulse valve 10>

[0093] The method for designing the shape of the nozzle orifice 123 will be described below. The shape of the nozzle orifice 123 is designed based on the fluid pressure, temperature, and desired resolution.

[0094] The method for designing the shape of the nozzle orifice 123 includes the steps of calculating the cross-sectional area at the discharge port of the nozzle orifice 123 and calculating the flow velocity of the fluid at the discharge port of the nozzle orifice 123 based on the pressure conditions and specific heat ratio at the inlet port of the nozzle orifice 123. The method for designing the shape of the nozzle orifice 123 also includes the steps of calculating the throat cross-sectional area of ​​the nozzle orifice 123, calculating the shape of the nozzle orifice 123 in the first region R1, and calculating the shape of the nozzle orifice 123 in the second region R2.

[0095] The steps for calculating the cross-sectional area of ​​the discharge port of nozzle orifice 123 will be described. Pulse valve 10 discharges a fluid containing supercritical fluid and applies the fluid to base material 12 with a desired resolution. Therefore, the cross-sectional area At of the discharge port of nozzle orifice 123 is preferably a desired value.

[0096] Next, the steps for calculating the fluid velocity at the discharge port of nozzle orifice 123 based on the pressure conditions and specific heat ratio at the inlet port of nozzle orifice 123 will be described. The pressure condition at the inlet port can be the inlet pressure. The flow velocity can be the Mach number.

[0097] The discharge port x of nozzle orifice 123 is x t The Mach number M of the fluid velocity at that location t As shown in expression (1), it is represented by the one-dimensional entropy flow formula. Symbol P о It is the inlet pressure (Pa), p t γ is the outlet pressure (Pa), and γ is the specific heat ratio, expressed as expression (2).

[0098] [Expressions 1 and 2]

[0099]

[0100] In expression (2), c p It is the specific heat at constant pressure, c v The specific heat of the constant product is expressed as expressions (3) to (5) described below. Expressions (3) to (5) are based on the thermodynamic equation of state, which is described in: Roland Span, 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 density, ρ c It is the critical density, and T is the temperature. c It is the critical temperature, and δ and τ are variables.

[0101] [Expressions 3 to 5]

[0102]

[0103] Next, the steps for calculating the throat cross-sectional area of ​​nozzle orifice 123 will be described. When the throat cross-sectional area is A... At that time, based on J. Conrad Crown, “Supersonic Nozzle Design”, NACA Technical Note No. 1651, it is expressed as the expression described below (6).

[0104] [Expression 6]

[0105]

[0106] Next, the steps for calculating the shape of the nozzle orifice 123 in the first region R1 will be described. Assume... Figure 5 The streamline at the throat (x=0) is parallel to the x-axis, and a radial line is drawn around any point through the streamline at the inflection point P1(x1, y1). Then, for y1 in the first region R1, the expression (7) described below is obtained geometrically. However, y0 is the distance from the central axis of the valve at the throat in the lateral direction, and θ1 is the angle between the tangent at the inflection point P1(x1, y1) and the central axis of the nozzle orifice 123.

[0107] [Expression 7]

[0108]

[0109] Based on the relationship between the Mach number and cross-sectional area of ​​entropy flow, A1 / A This is represented as expression (8).

[0110] [Expression 8]

[0111]

[0112] The Mach number M1 at the inflection point P1(x1, y1) is represented by the implicit numerical method in expression (9).

[0113] [Expression 9]

[0114]

[0115] In expression (9), v is represented by the Prandtl–Meyer function as described below in expression (10).

[0116] [Expression 10]

[0117]

[0118] In the first region R1, assuming that the shape of the nozzle orifice 123 in the first region R1 is a cubic curve, the value of x1 is represented by the expression (11) described below.

[0119] [Expression 11]

[0120]

[0121] When x1 and y1 are substituted into expression (11) and x1 is rearranged, the expression (12) described below is obtained.

[0122] [Expression 12]

[0123]

[0124] As described above, by changing the value of x from 0 to x1, the shape of the nozzle orifice 123 in the first region R1 can be calculated.

[0125] Finally, the steps for determining the shape of the nozzle orifice 123 in the second region R2 will be described. In the first region R1, the point P2 where the nozzle orifice 123 intersects the Mach line L1 starting from the inflection point P1 has a vector r and an angle θ starting from the same origin as r1.

[0126] At this point, θ is the angle between the streamline and the central axis of the nozzle orifice 123, and the variable r is the distance from the intersection of the tangent at inflection point P1 and the central axis of the nozzle orifice 123 to the intersection of the streamline and the Mach line L1. The point where the Mach line L2 starting from point P2 intersects the nozzle orifice 123 is denoted by Q, the point where the arc passing through point P2 with radius r intersects the nozzle orifice 123 is denoted by P', the point from point Q perpendicular to the streamline passing through point P2 is denoted by Q', and the distance between point P2 and point Q is denoted by l.

[0127] That is, variable l is the length of Mach line L2. Variable α is the angle with Mach line L2, which is a straight line connecting the intersection of the streamline and Mach line L1 to the intersection of the perpendicular line from the streamline to the surface of the nozzle orifice 123. At this point, the expression (13) described below is obtained based on the continuity expression and the geometric relation expression.

[0128] [Expression 10]

[0129]

[0130] When the expression (13) is rearranged with respect to the distance l between point P2 and point Q, the expression (14) described below is obtained. Expressions (15) to (18) represent the expressions for the parameters in expression (14).

[0131] [Expression 11]

[0132]

[0133] As described above, we obtain expressions (19) and (20) as described below.

[0134] [Expression 12]

[0135]

[0136] The shape of the nozzle orifice 123 in the second region R2 can be changed by altering the Mach number M from M1 to M... t To calculate.

[0137] <Design Example of Nozzle Orifice 123 of Pulse Valve 10>

[0138] Figures 6A to 6C This is a view showing a design example of the shape of the nozzle orifice 123 of the pulse valve 10. The illustrated example is based on the steps described in the above-described <Method for Designing the Nozzle Orifice 123 of the Pulse Valve 10>.

[0139] Figures 6A to 6C The diagram illustrates the case where the inlet pressure changes from 10 MPa to 50 MPa when carbon dioxide fluid at a temperature of 120 °C is discharged from nozzle orifice 123. Figure 6A This illustrates the case where the diameter of the discharge port section, which serves as the desired resolution for nozzle orifice 123, is 100 μm. Figure 6B This shows the case at 50 μm. Figure 6C The case at 200 μm is shown.

[0140] exist Figures 6A to 6C In, with Figure 5 As in the example, the axis corresponding to the central axis of the nozzle orifice 123 is set as the X-axis, the axis perpendicular to the central axis of the nozzle orifice 123 at the throat of the nozzle orifice 123 is set as the Y-axis, and the value of Y on the central axis of the nozzle orifice 123 is set as Y=0.

[0141] As shown in the example, in the case of pulse valve 10, a nozzle plate 120 with a suitable nozzle orifice 123 shape can be formed according to the fluid to be discharged, temperature, pressure, and desired resolution.

[0142] <Operation and Effects>

[0143] The shape of the nozzle orifice 123 in the pulse valve 10 is a Laval shape based on the cross-sectional area of ​​the discharge port and the pressure of the fluid at the inflow port. Therefore, by contracting the flow of fluid from the inflow port at the throat to make the flow velocity equal to or higher than the speed of sound and slowly 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 orifice 123 can be formed from the discharge port. Thus, the pulse valve 10 is able to apply fluid to the base material 12 with the desired resolution.

[0144] In the pulse valve 10, the protrusion 111a of the housing portion 110 and the outer diameter portion of the orifice 131 are fitted into the recess 121 of the nozzle plate 120, and the housing portion 110 and the nozzle plate 120 are fastened by clamping the orifice 131. Therefore, the pulse valve 10 has a structure that can withstand high-pressure fluids while utilizing the shape of the nozzle orifice 123.

[0145] A pulse valve includes: a housing portion having a channel for allowing a fluid containing a supercritical fluid to flow through the channel; a nozzle plate having a Laval-shaped nozzle orifice for discharging fluid flowing through the channel in a central axial direction of the nozzle orifice; an orifice having an opening communicating with the channel, the orifice being disposed between the housing portion and the nozzle plate in the central axial direction; and a valve needle inserted into the housing portion to abut against the opening of the orifice, thereby openably closing the channel.

[0146] The nozzle orifice is axially symmetrical with respect to its central axis. The nozzle orifice has an inlet for fluid to flow into the nozzle orifice, an outlet port for discharging fluid from the nozzle orifice, a throat located between the inlet and outlet port in the direction of the central axis, and an inflection point located between the throat and outlet port in the direction of the central axis. The nozzle orifice has a cross-sectional area that increases from the throat to the outlet port along the direction of the central axis, wherein the rate of change of cross-sectional area in the first region from the throat to the inflection point in the direction of the central axis is positive, and the rate of change of cross-sectional area in the second region from the inflection point to the outlet port in the direction of the central axis is negative.

[0147] The shape of the nozzle orifice is represented by the above expression (i) in the first region and by the above expressions (ii) and (iii) in the second region, where x is the distance from the throat in the nozzle orifice to the discharge port in the direction of the central axis, y is the distance from the central axis of the nozzle orifice in the transverse direction orthogonal to the direction of the central axis, y0 is the distance from the central axis of the nozzle orifice at the throat in the transverse direction, θ is the angle between the streamline and the central axis of the nozzle orifice, θ1 is the angle between the tangent at the inflection point and the central axis of the nozzle orifice, (x1, y1) are the xy coordinates at the inflection point, and r, α and l are variables.

[0148] The nozzle plate has a recess into which the orifice engages, and the housing portion includes a protrusion that engages with the recess of the nozzle plate and contacts the orifice. The nozzle plate is detachably attached to the housing portion. The pulse valve includes a drive mechanism and an actuator. The drive mechanism includes an extension rod coupled to the valve needle, and the extension rod is made of super invar material. The actuator reciprocates the extension rod to reciprocate the valve needle in the direction of the central axis.

[0149] The actuator includes a piezoelectric actuator. The piezoelectric actuator includes a ring actuator. The pulse valve includes a heat-insulating flange between the housing portion in the direction of the central axis and the drive mechanism. A coating apparatus includes the pulse valve.

[0150] Although the embodiments have been described above, this embodiment is not limited to the above embodiments, and various modifications and improvements can be made within the scope of this embodiment.

[0151] Aspects of this embodiment are described below, for example.

[0152] Aspect 1

[0153] According to aspect 1, a pulse valve includes:

[0154] The housing portion is configured to have channels through which a fluid containing supercritical fluid flows;

[0155] A nozzle plate configured to have nozzle orifices for discharging fluid flowing through the channel;

[0156] A valve needle, configured to insert into the housing portion and open and close the channel; and

[0157] An orifice, configured to have an opening and adjacent to the valve needle, for opening and closing the channel.

[0158] The nozzle orifice therein has a Laval shape.

[0159] Aspect 2

[0160] According to aspect 2, in the pulse valve of aspect 1,

[0161] The shape of the nozzle orifice is based on the cross-sectional area at the discharge port and the pressure of the fluid at the inflow port.

[0162] The shape is axially symmetrical with respect to the central axis of the nozzle orifice and includes an inflection point in the cross-section including the central axis of the nozzle orifice. The shape is a protruding shape facing the central axis side of the nozzle orifice in a first region from the throat to the inflection point, and a protruding shape facing the side opposite to the central axis of the nozzle orifice in a second region from the inflection point to the discharge port.

[0163] Aspect 3

[0164] According to aspect 3, in the pulse valve of aspect 2,

[0165] The shape of the nozzle orifice is:

[0166] The first region is represented by the following expression (i), and

[0167] The second region is represented by the following expressions (ii) and (iii).

[0168] When the distance from the throat of the nozzle orifice is defined as x, and the distance from the central axis of the nozzle orifice in the lateral direction is defined as y,

[0169] Where y0 is the distance from the central axis of the nozzle orifice at the throat in the lateral direction, θ is the angle between the streamline and the central axis of the nozzle orifice, θ1 is the angle between the tangent at the inflection point and the central axis of the nozzle orifice, the coordinates (x1, y1) are the xy coordinates at the inflection point, and r, α, l are variables.

[0170] [Expression 13]

[0171]

[0172] Aspect 4

[0173] According to aspect 4, in any of aspects 1 to 3, the pulse valve

[0174] The housing portion includes a protrusion that fits into a recess in the nozzle plate and is adjacent to the orifice.

[0175] The nozzle plate includes a recess that mates with the orifice.

[0176] Aspect 5

[0177] According to aspect 5, in any of aspects 1 to 4, the pulse valve

[0178] The nozzle plate can be attached to the housing and can also be removed from the housing.

[0179] Aspect 6

[0180] According to aspect 6, the pulse valve in any one of aspects 1 to 5 further includes:

[0181] A drive mechanism configured to move the valve needle forward and backward in the direction of the central axis of the pulse valve;

[0182] The drive mechanism includes:

[0183] An extension rod, which is connected to the valve needle and comprises a super Invar alloy material, and

[0184] An actuator that moves the extension rod forward and backward.

[0185] Aspect 7

[0186] According to aspect 7, in the pulse valve of aspect 6,

[0187] The actuator is a piezoelectric actuator.

[0188] Aspect 8

[0189] According to aspect 8, in the pulse valve of aspect 7,

[0190] The piezoelectric actuator is a ring actuator.

[0191] Aspect 9

[0192] According to aspect 9, in any of aspects 6 to 8, the pulse valve

[0193] The heat insulation flange is located between the housing part and the drive mechanism.

[0194] Aspect 10

[0195] According to aspect 10, a coating apparatus includes:

[0196] The pulse valve is described in any one of aspects 1 to 9.

[0197] The above embodiments are illustrative and do not limit the invention. Therefore, many additional modifications and variations are possible based on the above teachings. For example, within the scope of the invention, elements and / or features of different illustrative embodiments may be combined with and / or substituted for each other.

[0198] This patent application is based on and claims priority to Japanese Patent Application No. 2024-039615, filed on March 14, 2024, with the Japan Patent Office, the entire disclosure of which is incorporated herein by reference.

[0199] [List of reference numerals]

[0200] 1. Coating device

[0201] 10 Pulse Valve

[0202] 110 Casing Section

[0203] Channel 112

[0204] 120 Nozzle Plate

[0205] 123 Nozzle orifice

[0206] 130 valve needle

[0207] 131 orifice

[0208] 131a Opening

[0209] 140 drive mechanism

[0210] 142 Actuator

[0211] 150 thermal insulation flange

[0212] P1 Inflection Point

[0213] R1 First Area

[0214] R2 Second Region

[0215] [List of Citations]

[0216] [Patent Literature]

[0217] [Patent Document 1]

[0218] Japanese Unexamined Patent Application Publication No. 2009-30669

Claims

1. A pulse valve, comprising: The housing portion has a channel through which a fluid containing supercritical fluid flows; A nozzle plate having a Laval-shaped nozzle orifice for discharging fluid flowing through the channel in the direction of the central axis of the nozzle orifice; An orifice having an opening communicating with the channel, the orifice being disposed between the housing portion and the nozzle plate in the direction of the central axis; and A valve needle is inserted into the housing portion to abut an opening of the orifice, thereby enabling the passage to be closed openably.

2. The pulse valve according to claim 1, The nozzle orifice is axially symmetrical with respect to its central axis. The nozzle orifice has: The fluid in the channel flows from the inlet into the nozzle orifice; A discharge port for discharging the fluid from the nozzle orifice; A throat, located between the inlet and the outlet port in the direction of the central axis; and The inflection point is located between the throat and the discharge port in the direction of the central axis. The nozzle orifice has a cross-sectional area that increases from the throat to the discharge port along the central axis, wherein: In the first region from the throat to the inflection point along the central axis, the rate of change of the cross-sectional area is positive; and In the second region along the central axis from the inflection point to the discharge port, the rate of change of the cross-sectional area is negative.

3. The pulse valve according to claim 2, The nozzle orifice has the following shape: The first region is represented by the following expression (i); and The second region is represented by the following expressions (ii) and (iii). Where x is the distance from the throat to the discharge port in the nozzle orifice along the central axis. y is the distance from the central axis of the nozzle orifice in the transverse direction orthogonal to the central axis. y0 is the distance in the lateral direction from the central axis of the nozzle orifice at the throat. θ is the angle between the streamline and the central axis of the nozzle orifice. θ1 is the angle between the tangent at the inflection point and the central axis of the nozzle orifice. (x1, y1) are the x and y coordinates at the inflection point, and r, α, and l are variables. [Expression 1] 。 4. The pulse valve according to claim 1, The nozzle plate has a recess, and the orifice fits into the recess. The housing portion includes a protrusion that fits into a recess in the nozzle plate and contacts the orifice.

5. The pulse valve according to claim 1, The nozzle plate is detachably attached to the housing portion.

6. The pulse valve according to claim 1, further comprising a driving mechanism, the driving mechanism comprising: An extension rod is connected to the valve needle, and the extension rod is made of super Invar alloy material; and An actuator that reciprocates the extension rod to cause the valve needle to reciprocate in the direction of the central axis.

7. The pulse valve according to claim 6, The actuator mentioned above includes a piezoelectric actuator.

8. The pulse valve according to claim 7, The piezoelectric actuator mentioned above includes a ring actuator.

9. The pulse valve of claim 6 further includes a heat-insulating flange between the housing portion and the drive mechanism in the direction of the central axis.

10. A coating apparatus, comprising: The pulse valve according to any one of claims 1 to 9.

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