Plasma generator

Abstract

This plasma generation device comprises: one electrode; a case that comprises a conductor and that has a cylindrical inner space; a nozzle that comprises a conductor, that is installed so as to be able to rotate around the central axis of the inner space of the nozzle case, and that ejects a generated plasma gas; a fluid supply device that supplies a fluid into the internal space; a rotation mechanism that comprises an insulator and that rotates the nozzle by using the fluid supplied by the fluid supply device; a conduction path that is formed between the nozzle case and the nozzle; and a power source that applies voltage to the electrode. The nozzle case is grounded, and the plasma gas is generated due to a potential difference between the electrode to which the voltage has been applied by the power source, and the nozzle which is grounded by the conduction path.

Description

Technical Field

[0001] The present disclosure relates to a plasma generation device that generates plasma at atmospheric pressure.

Background Art

[0002] Patent Document 1 describes a plasma nozzle having a casing with a diameter-expanded portion at the upper part, and a plasma nozzle that is rotatably held with respect to a fixed support tube by a bearing at the diameter-expanded upper part. A ceramic pipe is inserted into the fixed support tube, and a spiral system having an electrode is inserted inside the ceramic pipe. High-frequency alternating current is supplied to the electrode. The casing is made of metal and is grounded through a bearing and a fixed support tube, functions as a counter electrode, and an arc discharge is generated between the electrode and the casing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the plasma nozzle described in Patent Document 1, since current also flows through the bearing as described above, bearing damage, lubrication deterioration, etc. occur or progress due to electrolytic corrosion, and as a result, the product life may be shortened.

[0005] An object of the present disclosure is to provide a technique capable of extending the product life.

Means for Solving the Problems

[0006] To achieve the above objective, the plasma generator of this disclosure comprises one electrode, a nozzle case made of a conductor having a cylindrical internal space, a nozzle made of a conductor rotatably mounted around the central axis of the internal space of the nozzle case and ejecting the generated plasma gas, a fluid supply device for supplying fluid into the internal space, a rotation mechanism made of an insulator for rotating the nozzle with the fluid supplied by the fluid supply device, a conductive path formed between the nozzle case and the nozzle, and a power supply for applying a voltage to the electrode. The nozzle case is grounded, and the plasma gas is generated by the potential difference between the electrode to which a voltage is applied by the power supply and the nozzle grounded by the conductive path. The nozzle has a cylindrical outer surface, and the rotation mechanism is a bearing made of an insulator that pivotally supports the outer surface of the nozzle as an axis. A conductor vane section is attached to the outer surface of the nozzle, which has vanes that receive the fluid supplied into the internal space. The nozzle rotates when the vanes, which receive the fluid supplied into the internal space, generate a rotational force in the vane section, and this rotational force is transmitted to the nozzle. do. Furthermore, the plasma generator of this disclosure comprises a nozzle case having one electrode, a cylindrical internal space, a fluid supply port for supplying fluid into the internal space, and a fluid discharge port for discharging the fluid from the internal space, a nozzle rotatably mounted around the central axis of the internal space of the nozzle case and ejecting the generated plasma gas, a fluid supply / discharge device that supplies fluid to the fluid supply port and discharges fluid from the fluid discharge port, a conductive path formed between the nozzle case and the nozzle, and a rotating mechanism made of an insulator that rotates the nozzle with the fluid supplied by the fluid supply / discharge device, the nozzle having an inlet for introducing the generated plasma gas into the nozzle and an ejection port for ejecting the introduced plasma gas to the outside, the ejection port being located inside the internal space The fluid supply and discharge device is formed at a position offset from the central axis between the two parts. It supplies fluid into the internal space from the fluid supply port and discharges the fluid from the internal space from the fluid discharge port, thereby rotating the nozzle. The nozzle case is grounded. Plasma gas is generated by the potential difference between the electrode to which voltage is applied and the nozzle which is grounded via a conductive path. The nozzle has a cylindrical outer surface. The rotation mechanism is a bearing made of an insulator that pivotally supports the outer surface of the nozzle as an axis. A conductor vane section, which has vanes that receive the fluid supplied into the internal space, is attached to the outer surface of the nozzle. The nozzle rotates when the vanes that receive the fluid supplied into the internal space generate a rotational force in the vane section, and this rotational force is transmitted to the nozzle. [Effects of the Invention]

[0007] According to this disclosure, it will be possible to extend the product lifespan. [Brief explanation of the drawing]

[0008] [Figure 1] This block diagram shows a schematic configuration of a plasma generator according to one embodiment of the present application. [Figure 2] Figure 1 is a perspective view showing the external appearance of the plasma generator included in the plasma generating device. [Figure 3] This is a partial cross-sectional view of the plasma generator when it is cut along line AA in Figure 2. [Figure 4] Figure 2 shows a partial cross-sectional view of the plasma generator when it is cut along line BB. [Figure 5] Figure 2 is a perspective view showing the components installed in the nozzle case of the plasma generator. [Figure 6] Figure 3 is an enlarged partial cross-sectional view showing the nozzle case and its vicinity within the plasma generator. [Figure 7] This diagram illustrates the mechanism by which the nozzle installed in the nozzle case shown in Figure 5 rotates. [Figure 8] Figure 5 is an enlarged perspective view showing a close-up of the contact plate attached to the blade portion installed in the nozzle case. [Modes for carrying out the invention]

[0009] The embodiments of this disclosure will be described in detail below with reference to the drawings.

[0010] Figure 1 shows a schematic configuration of a plasma generator 1 according to the first embodiment of the present application. The plasma generator 1 of this embodiment generates plasma gas under atmospheric pressure and performs plasma treatment on a workpiece by injecting the plasma gas into the workpiece.

[0011] As shown in Figure 1, the plasma generator 1 mainly consists of a plasma generator 20 that generates plasma gas and a control device 100 that controls the plasma generator 20.

[0012] The plasma generator 20 includes an electrode 34, a processing gas supply device 90, and an air supply / discharge device 92. The processing gas supply device 90 supplies the processing gas, which is the basis of the plasma gas, to the gas passage 30 (see Figure 4), which will be described later. The processing gas is a mixture of an inert gas such as a rare gas or nitrogen gas and an active gas such as oxygen in a predetermined ratio. The electrode 34 is installed in the reaction chamber 33 (see Figure 3), which will be described later, and generates a pseudo-arc in the reaction chamber 33. The processing gas is plasma-generated as it passes through this pseudo-arc, becoming plasma gas. The air supply / discharge device 92 supplies air to the air supply port 23a formed in the nozzle case 23, which will be described later using Figure 7, and discharges air from the air discharge port 23b formed in the nozzle case 23.

[0013] The control device 100 includes a controller 102 mainly composed of a computer, a control circuit 104 for controlling the electrodes 34, a first drive circuit 106 for driving the processing gas supply device 90, and a second drive circuit 108 for driving the air supply and discharge device 92.

[0014] The controller 102 controls the applied voltage to the electrode 34 by controlling the control circuit 104. Also, the controller 102 controls the supply amount of the processing gas supplied by the processing gas supply device 90 by controlling the first drive circuit 106. Further, the controller 102 controls the supply amount and discharge amount of the air supplied and discharged by the air supply / discharge device 92 by controlling the second drive circuit 108.

[0015] Figure 2 shows the appearance of the plasma generator 20. As shown in Figure 2, the plasma generator 20 has a main body 21, a connection terminal attachment portion 22, and a nozzle case 23. And, a gas pipe connection terminal 24 for connecting a gas pipe (not shown) that supplies the processing gas and a power cable connection terminal 25 for connecting the power cable 200 (see Figure 4) are attached to the connection terminal attachment portion 22. In Figures 2 to 7, when referring to directions, the directions of the arrows shown in each figure shall be used.

[0016] As shown in Figure 4, the gas pipe connection terminal 24 is connected to one end of a gas passage 30 having an L-shaped cross section provided in the connection terminal attachment portion 22, and the other end of the gas passage 30 is connected to the peripheral wall of a cable passage 31 to which the power cable connection terminal 25 is connected. Therefore, as shown in Figure 3, a hole 31a is formed in the peripheral wall thereof. As shown in Figure 4, the inner diameter of the cable passage 31 is formed larger than the outer diameter of the power cable 200, and the cable passage 31 also functions as a passage for the processing gas. Arrow A1 indicates a part of the flow of the processing gas, but the processing gas supplied from the gas pipe connection terminal 24 flows into the cable passage 31 via the gas passage 30.

[0017] The upper end of the cable passage 31 is connected to the power cable connection terminal 25 as described above, and the lower end of the cable passage 31 is connected to the upper end of the gas passage 32 formed inside the main body 21. And the lower end of the gas passage 32 is connected to the upper end of the reaction chamber 33 for generating plasma gas. The lower end of the reaction chamber 33 is tapered and has the same diameter as the plasma gas inlet 41 of the nozzle 40. Also, the electrode 34 is provided in the reaction chamber 33 so as to extend downward.

[0018] As shown in FIG. 6, a cylindrical internal space 23c is formed in the nozzle case 23, and the nozzle 40, the blade part 50, the two bearings 60, 70, and the support member 80 are installed in the internal space 23c. The two bearings 60, 70 are made of an insulator, for example, ceramic, and the nozzle case 23, the nozzle 40, and the blade part 50 are made of a conductor, for example, metal. And the nozzle case 23 is grounded.

[0019] The nozzle 40 injects the plasma gas introduced into the plasma gas inlet 41 to the outside, and the lower end is open and functions as the injection port 42. The diameter of the injection port 42 is formed shorter than the diameter of the plasma gas inlet 41, and the center of the injection port 42 extends the center of the plasma gas inlet 41 vertically downward and is shifted outward from the position where it intersects the lower end surface of the nozzle 40 (this position is the same as the position of the central axis of the internal space 23c). This is because the nozzle 40 is installed rotatably around its central axis in the internal space 23c and injects plasma gas from the injection port 42 while rotating. At this time, it is for irradiating the object to be processed with plasma gas over a wide range. The arrow A2 shows an example of the flow of the plasma gas introduced into the plasma gas inlet 41 of the nozzle 40 until it is injected from the injection port 42.

[0020] As shown in Figure 5, the blade section 50 has multiple blades 52 formed on the outer circumferential surface of a cylindrical body 51. Each blade 52 receives air supplied and discharged by the air supply / discharge device 92, generating rotational force in the blade section 50. The blade section 50 is attached to the nozzle 40 by pressing the inner circumferential surface of the body 51 against the outer circumferential surface of the body 43 of the nozzle 40. A metal contact plate 53 is attached to at least one of the multiple blades 52, for example, by a metal screw 54 (see Figure 8). The contact plate 53 is provided to contact the inner circumferential surface of the internal space 23c of the nozzle case 23, so it is attached in a position where it can reliably contact the inner circumferential surface of the internal space 23c, for example, near the tip of the blade 52. Furthermore, since the contact plate 53 contacts the inner circumferential surface of the internal space 23c even when the blade section 50 is rotating, it is preferable to use a material with low contact resistance, such as spring steel with biasing force.

[0021] The two bearings 60 and 70 support the body 43 of the nozzle 40 as an axis, allowing the nozzle 40 to rotate smoothly. Bearing 60 is installed between the upper surface of the blade portion 50 and the lower surface of the flange portion 45 of the nozzle 40, and bearing 70 is installed between the lower surface of the blade portion 50 and the lower end of the body 43 of the nozzle 40.

[0022] Bearing 60 is a so-called ball bearing, in which the ball 63 (see Figure 6) is surrounded by an inner ring 61 and an outer ring 62. Bearing 70 is similarly a ball bearing, in which the ball 73 (see Figure 6) is surrounded by an inner ring 71 and an outer ring 72.

[0023] The support member 80 is installed on the bottom surface of the nozzle case 23 to support the inner ring 71 of the bearing 70.

[0024] Figure 7 is a diagram illustrating the mechanism by which the nozzle 40 installed in the nozzle case 23 rotates. An air supply port 23a and an air discharge port 23b are formed on the right side of the nozzle case 23 in the front-to-back direction. One end of an air pipe (not shown) is connected to the air supply port 23a, and the other end of the air pipe is connected to the air supply / discharge device 92. One end of an air pipe (not shown) is also connected to the air discharge port 23b, and the other end of the air pipe is connected to the air supply / discharge device 92.

[0025] The air supply and discharge device 92 simultaneously supplies and discharges air. As shown by arrow A3, air is supplied from the air supply and discharge device 92 to the air supply port 23a, and as shown by arrow A4, air is discharged from the air discharge port 23b to the air supply and discharge device 92. As a result, as shown by arrow A5, a clockwise rotational force is applied to the blade portion 50, and the same rotational force is applied to the nozzle 40 to which the blade portion 50 is attached. The nozzle 40 rotates on the bearings 60 and 70. Arrow A6 shows the blade portion 50 rotating clockwise.

[0026] In the plasma generator 20 configured as described above, the controller 102 controls the control circuit 104 to apply a voltage to the electrode 34 such that a pseudo-arc is generated from the electrode 34.

[0027] Furthermore, the controller 102 controls the first drive circuit 106 to supply processing gas from the processing gas supply device 90 to the gas passage 30 on the connection terminal mounting section 22 side. The processing gas supplied to the gas passage 30 is supplied to the reaction chamber 33 through the gas passage 32 on the main body 21 side. The processing gas is plasma-generated in the reaction chamber 33 and ejected as plasma gas from the nozzle 42 of the nozzle 40.

[0028] As described above, the plasma generation of the processing gas is achieved by generating a pseudo-arc in the reaction chamber 33 using the electrode 34, and passing the processing gas through this pseudo-arc. The pseudo-arc is generated between a pair of electrodes, but since the plasma generator 20 of this embodiment is only provided with one electrode 34, the nozzle 40 is made to function as the other electrode. In order to use the nozzle 40 as an electrode, a predetermined potential difference must be generated between the electrode 34 and the nozzle 40, so the nozzle 40 needs to be grounded. Since the nozzle case 23 is grounded as described above, it is necessary to form a conductive path between the nozzle 40 and the nozzle case 23. Therefore, in this embodiment, a conductive blade portion 50 is attached to the nozzle 40, and a conductive contact plate 53 is attached to the blade 52 of the blade portion 50 with a conductive screw 54, and the contact plate 53 is brought into contact with the inner circumferential surface of the internal space 23c of the nozzle case 23, thereby forming a conductive path between the nozzle 40 and the nozzle case 23.

[0029] In this way, a predetermined potential difference is generated between the electrode 34 and the nozzle 40, causing a pseudo-arc to form. However, if the bearings 60 and 70 are also included in the formed conductive path, galvanic corrosion can cause or progress bearing damage and lubrication deterioration in the bearings 60 and 70, which is problematic. Therefore, in this embodiment, bearings 60 and 70 are made only of insulating materials, for example, made of ceramic, to prevent current from flowing through the bearings 60 and 70.

[0030] Meanwhile, the controller 102 controls the second drive circuit 108 to supply air from the air supply / discharge device 92 to the air supply port 23a and to discharge air from the air discharge port 23b. As a result, each blade 52 receives the air supplied and discharged by the air supply / discharge device 92, generating rotational force in the blade section 50, so that the nozzle 40 rotates and the plasma gas ejected from the injection port 42 irradiates a wide area.

[0031] As described above, the plasma generator of this embodiment comprises one electrode 34, a nozzle case 23 made of a conductive material having a cylindrical internal space 23c, a nozzle 40 made of a conductive material that is rotatably mounted around the central axis of the internal space 23c of the nozzle case 23 and ejects the generated plasma gas, an air supply / discharge device 92 that supplies air into the internal space 23c, bearings 60 and 70 made of an insulating material that rotate the nozzle 40 with the air supplied by the air supply / discharge device 92, a conductive path formed between the nozzle case 23 and the nozzle 40, and a control circuit 104 that applies a voltage to the electrode 34. The nozzle case 23 is grounded, and the plasma gas is generated by the potential difference between the electrode 34 to which a voltage is applied by the control circuit 104 and the nozzle 40 which is grounded by the conductive path.

[0032] Thus, in the plasma generator 1 of this embodiment, even when a voltage is applied to the electrode 34 when generating plasma gas, no current flows through the bearings 60 and 70, and no electrolytic corrosion occurs. As a result, the lifespan of the bearings 60 and 70 is extended, and consequently, the product lifespan of the plasma generator 1 can be extended.

[0033] Incidentally, in this embodiment, air is an example of a "fluid." The air supply / discharge device 92 is an example of a "fluid supply device." The bearings 60 and 70 are an example of a "rotating mechanism." The control circuit 104 is an example of a "power supply."

[0034] Furthermore, the nozzle 40 has a cylindrical outer surface, and the bearings 60 and 70 are insulator bearings that pivotally support the nozzle 40 with its outer surface as an axis. A conductor vane portion 50, which has vanes 52 that receive air supplied into the internal space 23c, is attached to the outer surface of the nozzle 40. The nozzle 40 rotates when the vanes 52 that receive air supplied into the internal space 23c generate a rotational force in the vane portion 50, and this rotational force is transmitted to the nozzle 40.

[0035] Furthermore, the blade portion 50 has a contact plate 53 made of a conductive material that contacts the wall surface forming the internal space 23c of the nozzle case 23, and the conductive path is a path connecting the nozzle 40, the blade portion 50, the contact plate 53, and the wall surface forming the internal space 23c of the nozzle case 23.

[0036] Furthermore, the contact plate 53 is made of spring steel. This makes it possible to reduce the contact resistance when the nozzle 40 rotates.

[0037] The nozzle case 23 has a cylindrical internal space, an air supply port 23a for supplying external air into the internal space 23c, and an air discharge port 23b for discharging air from the internal space 23c. The nozzle 40 is rotatably mounted around the central axis of the internal space 23c of the nozzle case 23 and ejects the generated plasma gas. The air supply / discharge device 92 supplies air to the air supply port 23a and discharges air from the air discharge port 23b. The nozzle 40 has a plasma gas inlet 41 for introducing the generated plasma gas into the nozzle 40 and a nozzle 42 with a smaller diameter than the plasma gas inlet 41 for ejecting the introduced plasma gas to the outside. The nozzle 42 is formed at a position offset from the central axis of the internal space 23c. The air supply / discharge device 92 rotates the nozzle 40 by supplying air from the air supply port 23a into the internal space 23c and discharging the air from the internal space 23c through the air discharge port 23b.

[0038] In this embodiment, the plasma generator 1 supplies air into the internal space 23c from the air supply port 23a, and the air in the internal space 23c is discharged from the air discharge port 23b, thereby rotating the nozzle 40. This makes it possible to rotate the nozzle 40 at high speed and stably.

[0039] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0040] (1) In the above embodiment, the air supply / discharge device 92 is used to both supply and discharge air into the internal space 23c of the nozzle case 23, but it is also possible to do only one of them. Furthermore, the gas contained in the fluid is not limited to "air" as used in the above embodiment, but may be other types of gases, or it may not be limited to gases but may be a liquid.

[0041] (2) In the above embodiment, ball bearings were used as bearings 60 and 70, but the system is not limited to ball bearings, and other types of bearings may be used. However, they must be made of an insulator, as this would cause problems with electrolytic corrosion.

[0042] (3) In the above embodiment, only the processing gas was supplied to the reaction chamber 33, but an inert gas may also be supplied in addition. [Explanation of symbols]

[0043] 1...Plasma generator, 20...Plasma generator, 23...Nozzle case, 23a...Air supply port, 23b...Air exhaust port, 23c...Internal space, 34...Electrode, 40...Nozzle, 42...Injection port, 50...Blade section, 52...Blade, 53...Contact plate, 60, 70...Bearing, 90...Processing gas supply device, 92...Air supply / discharge device.

Claims

1. One electrode and, A nozzle case made of a conductive material having a cylindrical internal space, A nozzle made of a conductive material is rotatably mounted around the central axis of the internal space of the nozzle case and ejects the generated plasma gas. A fluid supply device that supplies fluid into the internal space, A rotating mechanism made of an insulator rotates the nozzle using the fluid supplied by the fluid supply device, A conductive path formed between the nozzle case and the nozzle, A power supply for applying voltage to the aforementioned electrode, Equipped with, The nozzle case is grounded, The plasma gas is generated by the potential difference between the electrode to which a voltage is applied by the power supply and the nozzle which is grounded by the conductive path. The nozzle has a cylindrical outer surface, The aforementioned rotation mechanism is a bearing made of an insulator that pivotally supports the outer circumferential surface of the nozzle as its axis. A conductor-made vane portion is attached to the outer circumferential surface of the nozzle, and the vane portion has vanes that receive the fluid supplied into the internal space. The nozzle rotates when the blades, receiving the fluid supplied to the internal space, generate a rotational force in the blade portion, and this rotational force is transmitted to the nozzle. Plasma generator.

2. The blade portion has a contact plate made of a conductive material that contacts the wall surface forming the internal space of the nozzle case, The conductive path is a path connecting the nozzle, the blade portion, the contact plate, and the wall surface forming the internal space of the nozzle case. The plasma generator according to claim 1.

3. The contact plate is made of spring steel. The plasma generator according to claim 2.

4. One electrode and A nozzle case having a cylindrical internal space, a fluid supply port for supplying fluid into the internal space, and a fluid discharge port for discharging the fluid in the internal space, A nozzle is rotatably mounted around the central axis of the internal space of the nozzle case and ejects the generated plasma gas, A fluid supply and discharge device that supplies fluid to the fluid supply port and discharges fluid from the fluid discharge port, A conductive path formed between the nozzle case and the nozzle, A rotating mechanism made of an insulator rotates the nozzle using the fluid supplied by the fluid supply and discharge device, Equipped with, The nozzle has an inlet for introducing the generated plasma gas into the nozzle and an ejection port for ejecting the introduced plasma gas to the outside. The injection nozzle is formed at a position offset from the central axis of the internal space, The fluid supply and discharge device rotates the nozzle by supplying fluid from the fluid supply port into the internal space and discharging the fluid from the internal space through the fluid discharge port. The nozzle case is grounded, The plasma gas is generated by the potential difference between the electrode to which a voltage is applied and the nozzle which is grounded by the conductive path. The nozzle has a cylindrical outer surface, The aforementioned rotation mechanism is a bearing made of an insulator that pivotally supports the outer circumferential surface of the nozzle as its axis. A conductor-made vane portion is attached to the outer circumferential surface of the nozzle, and the vane portion has vanes that receive the fluid supplied into the internal space. The nozzle rotates when the blades, receiving the fluid supplied to the internal space, generate a rotational force in the blade portion, and this rotational force is transmitted to the nozzle. Plasma generator.

Images