Inductively coupled plasma generator

Abstract

A conductive rod body is embedded in an insulative torch adapter into which a plasma torch is fitted so that a leading end protrudes from its outer circumferential surface. Further, a metal plate member electrically connected to a cable line to which a voltage for plasma ignition is applied is attached to a lower holder, and a conductive leaf spring member having a V-shaped cross section is attached to an upper holder. When the torch adapter is placed on the lower holder so that the protruding part of the rod body faces upward and the upper holder is closed to tighten a draw latch, the rod body and the metal plate member are electrically connected via the leaf spring member, and a high voltage for ignition can be applied to the plasma torch.

Claims

1. An inductively coupled plasma generator which supplies high-frequency power to an inductive coil disposed outside a leading end portion of a plasma torch having a substantially cylindrical outer shape to form an inductively coupled plasma flame at a leading end of the torch, the inductively coupled plasma generator comprising: a) a torch adapter which is a substantially flat annular insulative body having an opening portion into which the plasma torch is inserted, and within which a conductive rod body is disposed, the conductive rod body extending in a radial direction relative to the torch, one end of the conductive rod body being exposed to face the opening portion, and the other end of the conductive rod body protruding by a predetermined length toward an outer circumferential side; b) a torch holder which holds the plasma torch substantially horizontally by grasping the torch adapter into which the plasma torch is inserted, and has a lower holder which supports a lower side of the torch adapter, an upper holder which suppresses an upper side of the torch adapter, and an engaging part which fixes the upper holder to the lower holder in a state in which the torch adapter is interposed; and c) a conductive first member which is electrically connected to a cable line for applying a voltage for plasma ignition and provided in the upper holder, and has a first contact part which abuts on the rod body to press the rod body downward by an elastic force, when the upper holder is closed and engaged by the engaging part in a state in which the torch adapter is placed on the lower holder so that the protruding part of the rod body of the torch adapter faces upward.

2. The inductively coupled plasma generator according to claim 1, wherein the conductive first member is a conductive leaf spring member.

3. The inductively coupled plasma generator according to claim 1, wherein the torch adapter has an inner diameter of an opening portion corresponding to an outer diameter of a plasma torch to be used, and an outer diameter, which is a substantially flat annular body, is common regardless of the outer diameter of the plasma torch.

4. The inductively coupled plasma generator according to claim 1, wherein the upper holder is pivotally mounted about an axis substantially horizontal to the lower holder, and the engaging part is a draw latch which engages the upper holder and the lower holder in a state in which the upper holder is closed with respect to the lower holder.

5. The inductively coupled plasma generator according to claim 1, wherein a conductive second member extending vertically and electrically connected to a cable line for applying a voltage for plasma ignition is provided in the lower holder, and the conductive first member has a second contact part which abuts on the upper end of the conductive second member to press the second member downward by elastic force, when the upper holder is closed and engaged by the engaging part.

6. The inductively coupled plasma generator according to claim 2, wherein a conductive second member extending vertically and electrically connected to a cable line for applying a voltage for plasma ignition is provided in the lower holder, and the conductive first member has a second contact part which abuts on the upper end of the conductive second member to press the second member downward by the elastic force, when the upper holder is closed and engaged by the engaging part.

7. The inductively coupled plasma generator according to claim 3, wherein a conductive second member extending vertically and electrically connected to a cable line for applying a voltage for plasma ignition is provided in the lower holder, and the conductive first member has a second contact part which abuts on the upper end of the conductive second member to press the second member downward by the elastic force, when the upper holder is closed and engaged by the engaging part.

8. The inductively coupled plasma generator according to claim 4, wherein a conductive second member extending vertically and electrically connected to a cable line for applying a voltage for plasma ignition is provided in the lower holder, and the conductive first member has a second contact part which abuts on the upper end of the conductive second member to press the second member downward by the elastic force, when the upper holder is closed and engaged by the engaging part.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of an inductively coupled plasma generator according to an embodiment of the invention;

(2) FIG. 2 is a perspective view of a state in which an upper holder is seen through in the inductively coupled plasma generator of the present embodiment;

(3) FIG. 3 is a cross-sectional view taken along a Y-Z plane of a torch holder portion in the inductively coupled plasma generator of the present embodiment;

(4) FIG. 4 is a schematic cross-sectional view illustrating a state of a conductive leaf spring at the time of opening and closing the upper holder in the inductively coupled plasma generator of the present embodiment;

(5) FIG. 5 is a schematic configuration diagram of a conventional inductively coupled plasma generator; and

(6) FIG. 6 is a perspective view of a conventional inductively coupled plasma generator.

DETAILED DESCRIPTION

(7) Hereinafter, an inductively coupled plasma generator according to an embodiment of the invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of the inductively coupled plasma generator of this embodiment, FIG. 2 is a perspective view in a state in which an upper holder is seen through, FIG. 3 is a cross sectional view of the torch holder part in the Y-Z plane, and FIG. 4 is a schematic cross-sectional view illustrating a state of a conductive leaf spring at the time of opening and closing of the upper holder. For the sake of convenience, in FIGS. 1 to 4, an X-axis, a Y-axis and a Z-axis orthogonal to each other are set as illustrated. The same or corresponding constituent elements as those already described with reference to FIGS. 5 and 6 are denoted by the same reference numerals.

(8) A plasma torch 3 made of quartz glass, which is a coaxial triple cylindrical pipe structure similar to the conventional example, is fitted through a torch adapter 4 having a substantially flat annular outer shape. The torch adapter 4 is made of an insulator such as polytetrafluoroethylene (PTFE) resin, and as illustrated in FIGS. 3 and 4, a conductive rod body 41, which has one end exposed to an inner circumferential surface of a central opening portion and the other end extending outward from an outer circumferential surface, is buried in the torch adapter 4 to extend in the radial direction. Since the plasma torch 3 is fitted in the central opening portion of the torch adapter 4, the leading end of the rod body 41 on the inner circumferential side is in contact with the outer circumferential surface of the plasma torch 3. There is a plurality of types of plasma torch 3 having different outer diameters, but a plurality of torch adapters 4 having a central opening portion of an inner diameter corresponding to each outer diameter and having the same (common) outer diameter are prepared, and a torch adapter matching the outer diameter of the plasma torch is used. Therefore, even when any type of plasma torch is used, the outer diameter of the torch adapter 4 or a protruding length of the rod body 41 from the outer circumferential surface of the adapter 4 is the same.

(9) A torch holder 2 has a lower holder 21 fixed to a base 1 with a metal fitting fixing screw 31 via a metal fitting 30, and an upper holder 22 fixed to the lower holder 21 by a hinge 24 so as to be freely pivotable. The lower holder 21 and the upper holder 22 are made of an insulator such as polyethylene terephthalate (PET) resin. As can be seen from FIG. 3, although the lower holder 21 is not a single member but combinations of a plurality of members, it is obvious that the lower holder 21 may be made up of a single member. The upper holder 22 is free to pivot with respect to the lower holder 21 about an axis A (parallel to the X-axis in this example) of the hinge 24, and a draw latch (corresponding to the engaging part in the present invention) 23 is provided to fix the upper holder 22 to the lower holder 21 in a state in which the upper holder 22 is closed so as to sandwich the torch adapter 4 between the upper holder 22 and the lower holder 21. This is the same as the conventional configuration illustrated in FIG. 6.

(10) A metal plate member (corresponding to the conductive second member in the invention) 25 having a substantially L-shaped cross section is attached to the upper surface of the lower holder 21 so as to be accommodated in a gap formed between the lower holder 21 and the upper holder 22 when the upper holder 22 is closed. The distal end of a cable line 6, one end of which is connected to the ignition circuit, is fixed to the lower holder 21 by a wiring fixing plate fixing screw 27, in a state of being sandwiched between the metal plate member 25 and a wiring fixing plate 26 placed to overlap the top thereof. Thus, the electrical connection between the ignition circuit and the metal plate member 25 is secured through the cable line 6.

(11) The upper holder 22 integrally has a horizontal part 22a which is substantially horizontal in the state in which the upper holder 22 is closed, and an inclined part 22b which is inclined. Recessed parts 22c and 22d are formed on lower surfaces (surfaces on an inner side in a state in which the upper holder 22 is closed) of the horizontal part 22a and the inclined part 22b, respectively. The recessed part 22c on the side of the horizontal part 22a is formed at a position where the protruding part of the rod body 41 protruding just above the torch adapter 4 held by the lower holder 21 is received, when the upper holder 22 is closed. On the other hand, the recessed part 22d of the inclined part 22b side is formed at a position where the leading end of the vertically rising upright piece part of the metal plate member 25 fixed to the lower holder 21 is received, when the upper holder 22 is closed.

(12) A conductive leaf spring member (electrically conductive first member in the invention) 28 bent in a V-shaped cross section is fixed on the lower surface of the inclined part 22b of the upper holder 22, by a leaf spring fixing screw 29. One flexible piece 28a of the leaf spring member 28 extends to a position which substantially covers the recessed part 22c on the horizontal part 22a side, and the other flexible piece 28b of the leaf spring member 28 extends to a position which substantially covers the recessed part 22d on the inclined part 22b side.

(13) When the plasma torch 3 is mounted on the torch holder 2, the operator places the torch adapter 4 with the plasma torch 3 fitted in the central opening portion on a support receiving part 21a of the lower holder 21 so that the protruding part of the rod body 41 faces approximately directly above, in a state in which the draw latch 23 is unlocked and the upper holder 22 is opened so as not to cover the upper side of the lower holder 21. Further, as illustrated in FIG. 4b, when closing the upper holder 22 and tightening the draw latch 23, the plasma torch 3 is held by the torch holder 2 via the torch adapter 4. At this time, the leading end of the protruding part of the rod body 41 pushes one flexible piece 28a of the leaf spring member 28 upward (Z-axis direction), and the flexible piece 28a is deflected and enters the recessed part 22c. Since the rod body 41 is pushed downward by the elastic force of the deflected flexible piece 28a, electrical conduction through the contact part in which the leaf spring member 28 and the rod body 41 abut against each other is securely ensured. Further, since the torch adapter 4 is pressed against the support receiving part 21a of the lower holder 21 from above, positional deviation or the like is hard to occur and the torch adapter 4 is stably held.

(14) On the other hand, the upper end of the rising piece part of the metal plate member 25 pushes the flexible piece 28b of the leaf spring member 28 upward, and the flexible piece 28b is deflected to enter the recessed part 22d. That is, each of the recessed parts 22c and 22d is a space for escaping when the flexible pieces 28a and 28b of the leaf spring member 28 are deflected. Since the rising piece part of the metal plate member 25 is pushed downward by the elastic force of the deflected flexible piece 28b, the electrical conduction via the contact part in which the leaf spring member 28 and the metal plate member 25 abut against each other is surely ensured. Thus, in a state in which the plasma torch 3 is appropriately loaded and the draw latch 23 is tightened, electrical conduction between the metal plate member 25 and the rod body 41 via the leaf spring member 28 is ensured, and an electrical conduction path from the ignition circuit to the outer circumferential surface of the plasma torch 3 is secured. As a result, when a high-voltage pulse is generated in the ignition circuit, the high-voltage pulse can be reliably applied to the plasma torch 3 to ignite the plasma.

(15) Unlike the conventional device, in the inductively coupled plasma generator of this embodiment, since the operation of replacing the cable line 6 for plasma ignition at the time of replacing the plasma torch 3 is not necessary at all, replacement operation can be efficiently performed. This also applies to the case where the plasma torch is replaced for one having a different outer diameter.

(16) The above-mentioned embodiment is an example of the invention, and even when a change, a correction or an addition is appropriately made within the scope of the spirit of the invention, it is natural that they are included within the scope of the claims of the invention.

(17) For example, in the above embodiment, the distal end of the cable line 6 is fixed to the lower holder 21, and the electrical conduction between the cable line 6 and the plasma torch 3 is secured via the metal plate member 25 attached to the lower holder 21, the leaf spring member 28 attached to the upper holder 22, and the rod body 41 buried in the torch adapter 4. However, the distal end of the cable line 6 may be fixed to the upper holder 22 so that the cable line 6 is electrically connected to the leaf spring member 28 without passing through the metal plate member 25. However, in that case, as the upper holder 22 is opened and closed, an unnecessary load is applied to the cable line 6. Therefore, it is preferable that the distal end of the cable line 6 be fixed to the lower holder 21 instead of the upper holder 22.

(18) The means for fixing the upper holder 22 to the lower holder 21 when closing the upper holder 22 is not limited to the draw latch 23, another engaging means capable of performing a reliable engagement by a predetermined manipulation and operation of the operator may be used.