JPH02168588A - discharge tube - Google Patents

Abstract

PURPOSE:To obtain stabilized and high discharge voltage from initial period of discharge at a narrow interval of electrodes, and to disperse electrode consumption by means of increasing an electrode surface area by making a points of a pair of electrodes that are opposed each other in non-acute form, and by forming irregularities by providing holes on the surface. CONSTITUTION:A casing 2 of a discharge tube 1 is composed of an insulating tube of hollow cylinder of such as alumina ceramics or crystal glass, and a ridge 3 is provided in a longitudinal direction along an inner circumferential surface, while openings on both edges of the casing 2 are closed by the threading of a metallic electrode board 4. In the inner surface 4a of each electrode board 4 exposed in the casing 2, a Rogowskii type electrode 6 is opposed one another at a short interval through a metal ring 5, and the form of the electrode 6 is as follows: a point surface 6a is defined as a plane while a peripheral part 6b is rolled in a curved surface toward the ring 5 side, with multiple small holes 7 in each. In the inner space 8 of the discharge tube 1, inert gas, for example N1 is filled in, while the space between the casing 2 and the electrode board 4 is sealed with such as an epoxy resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a discharge tube, and more particularly to a discharge tube suitable for a series gap ignition device such as an automobile engine.

[Problems to be solved by conventional techniques and inventions] Generally,
2. Description of the Related Art Discharge tubes, in which gas is sealed inside the tube and a voltage is applied between electrodes provided at both ends of the tube to cause discharge, are widely used in various fields.

FIG. 9 shows a discharge tube 61 used in the series gap ignition device C for an automobile engine or the like shown in FIG. The inside is filled with inert gas.

The discharge tube 61 acts as a series gap S in the ignition device C, and this series gap S
By keeping the discharge voltage at a certain level high and applying the series gap voltage after discharge to the electrode of the spark plug P, the influence of electrical shunts caused by carbon etc. attached to the spark plug P can be reduced. The ignition voltage required for the ignition plug P can be obtained without receiving the ignition voltage.

However, as shown in FIGS. 1O and 11, the electrode 6 of the discharge tube 61 on the side to which the voltage of the ignition coil 65 is applied
3 is formed into a needle shape as described above, an uneven electric field is generated between the electrodes 63 and 64 of the discharge tube 61, which tends to cause discharge, and the discharge voltage .
There was a problem that 1 did not become very high. Therefore, in order to increase the discharge voltage V of the discharge tube 61 to a certain extent, the distance between the needle electrode 63 and the flat electrode 64, that is, the series gap S, is widened to a certain extent.

However, when the series gap S is widened in this way, there is a problem that the overall shape of the discharge tube becomes larger, and there is also a problem that the discharge sustaining voltage (2) in Fig. 12 increases, resulting in an increase in energy loss during discharge. there were. Furthermore, since the needle-shaped electrode 63 has a small electrode surface area, there is a problem that the electrode wears out due to discharge and is not very durable.

Therefore, the electrodes of the discharge tube 61 are a pair of substantially parallel plate electrodes (Logowski electrodes), which are often used in experiments on discharge phenomena, and have a flat tip and a rounded peripheral edge of the tip. , it is difficult to discharge by approximating an equal electric field between the electrodes of the discharge tube (discharge voltage ■1 shown in Figure 12).
In addition to increasing the discharge sustaining voltage, the electrode spacing is narrowed.
It is possible to reduce energy loss by lowering 2.

However, this Rogowski electrode is easily affected by the amount of electrons floating between the electrodes, and has the characteristic that electrons are difficult to emit from the electrodes, so the discharge voltage vl is not stable, and the discharge voltage ■1 is lower than the discharge frequency. The problem was that it was influenced by

Therefore, the present invention solves the problems of the above-mentioned conventional technology, and enables a high discharge voltage to be obtained with a relatively narrow electrode spacing, and
It is an object of the present invention to provide a discharge tube in which the obtained discharge voltage is stabilized.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a discharge tube in which a voltage is applied between a pair of electrodes to cause discharge between an anode side electrode and a cathode side electrode, in which the pair of electrodes are substantially opposite to each other. The distal end portion of the cathode electrode is formed in a non-sharp shape, and a large number of uneven portions are formed on at least the surface of the cathode side electrode.

[For production]

Since the opposing ends of the pair of electrodes are formed in a non-sharp shape, it is possible to approximate an equal electric field between the electrodes, and the electric field is small (both because many uneven parts are formed on the surface of the cathode side electrode). These uneven portions can also form an electric field that is microscopically similar to an unequal electric field.

〔Example〕

Embodiments of the discharge tube according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which reference numeral l indicates a discharge tube, and the casing 2 of the discharge tube l is a hollow body made of ceramics such as alumina ceramics, steatite, and crystallized glass. It is formed as a cylindrical insulating tube. A thread 3 is provided on the inner peripheral surface of the casing 2 in the longitudinal direction, and metal electrode stands 4, 4 are screwed so as to close the openings at both ends of the casing 2. On the inner surfaces 4a, 4a of each electrode stand located in the casing 2, Rogowski type electrodes 6, 6 formed of a material passed through an electric discharge are arranged so as to face each other at a relatively narrow interval via a metal ring 5. It is provided.

The Rogowski type electrode 6 is a type of substantially flat plate electrode with a non-pointed tip, in which the tip surface 6a is flat and the peripheral edge 6b of the tip surface 6a is rounded toward the metal ring 5 side to form a curved surface. However, the electrode 6 of the present invention has a larger number of small holes 7 formed therein. In order to form such a Rogowski-type electrode 6 with holes, for example, a thin stainless steel plate with a thickness of 0.2 m is etched or punched so that the hole pitch is 0.5 rm - 1.5 ml and the diameter is A small hole 7 with a diameter of O,ltm~0.8M may be formed, and a thin stainless steel plate with this hole 7 opened may be press-molded.

In addition, in order to attach the Rogowski type electrode 6 to the electrode stand 4, the base end of the electrode 6 is externally fitted onto the boss portion 4b protruding from the inner surface 4a of the electrode stand, and the metal ring 5 is forcefully submerged. That's what I do. Here, the electrode pedestal 4 is preferably made of a material having a coefficient of thermal expansion almost equal to that of the casing 2 and a small value, such as 4270I or Kovar, and the metal ring 5 has a coefficient of thermal expansion approximately equal to that of the casing 2. Preferably, it is equal to or smaller than the electrode stand 4.

Furthermore, the internal space 8 of the discharge tube 1 is filled with an inert gas such as nitrogen gas, and an epoxy adhesive is used between the casing 2 and the electrode stand 4 to prevent the sealed gas from leaking. It is sealed with a sealing material 9 such as , glass adhesive, metallizing brazing, etc.

According to the above-mentioned configuration, since the pair of electrodes 6, 6 of the discharge tube 1 are both of the Rogowski type and the distance between the electrodes is narrow, it is possible to approximate an equal electric field between the electrodes 6.6 of the discharge tube 1. A discharge tube can be obtained which is difficult to discharge, has a high discharge voltage (2) shown in FIG. 10, and has a low discharge sustaining voltage (8) and little energy loss. Also, discharge tube 1
Since a large number of small holes 7 are formed in the electrode 6 and a large number of uneven parts are formed on the electrode surface, microscopically the small holes 7L are formed in the electrode 6.
7, an electric field similar to an unequal electric field is formed and electrons are easily emitted from the electrodes, so that the discharge voltage vI, which is a characteristic of the unequal electric field, is stabilized and a discharge tube that is not affected by the discharge frequency can be obtained.

In particular, since the pair of electrodes 6 and 6 are formed as a Rogowski type, it is possible to prevent the electric field from concentrating on the periphery of the flat plates and having an unfavorable effect on the discharge characteristics when simply parallel flat plates are opposed. This allows discharge to occur only in a parallel electric field.

Furthermore, the thermal expansion coefficients of the casing 2 and the electrode stand 4 are made almost the same, and the electrode 6 made of a material suitable for electric discharge is attached to the electrode stand 4, so that the discharge tube l can withstand heat cycles. It is possible to have a strong structure, maintain a sealed state between the casing 2 and the electrode stand 4, and prevent leakage of the inert gas sealed in the tube.

Furthermore, since the electrode 6 is formed as a type of flat plate electrode and has a larger electrode surface area than a conventional needle-shaped electrode, the electrode is less affected by electrode wear due to discharge and has good durability.

In the above-mentioned discharge tube 1, the pair of electrodes 6, 6 provided opposite to each other are both of the same perforated Rogowski type, so that one electrode is a cathode and the other is an anode. The tube itself has no directionality, and impulse signals can be applied to any electrode. Therefore, the discharge tube 1 can also be used as an AC power source.

By the way, as a result of conducting various experiments by forming a discharge tube l having the Rogowski-type electrode 6 described above, it was found that in the discharge voltage characteristics shown in FIG. It has been found that the discharge sustaining voltage V2 is determined by the material, shape, electrode spacing, type and pressure of the charged gas, and the level of the discharge sustaining voltage V2 is determined by the electrode spacing and the conditions of the filled gas.

Therefore, it was found that the shape of the anode side electrode does not matter much as long as the electrode on the cathode side is the same perforated Rogowski type as in the above example. An example in which only the electrode on the anode side is modified will be described. Note that the structure of the cathode side electrode is the same as that in the previous embodiment, so its explanation will be omitted.

In FIGS. 2A and 2B, the anode side electrodes are both formed into a flat plate shape. In the case of discharge pipe construction 0 in FIG.
A large number of small holes 13 are provided on the surface of the electrode 11.
is formed.

The method of forming this small hole 13 is the same as the processing method shown in the above embodiment.

Therefore, in the case of this embodiment, the obtained voltage characteristics are almost the same as those of the discharge tube 1 of the above embodiment, and since the electrode 11 on the anode side is changed from a Rogowski type to a flat plate shape, the longitudinal length of the casing 14 can be made smaller, and the entire discharge tube lO can be made smaller. However, the Rogowski type electrode 6 is a cathode, and the flat electrode 11 is not a cathode.
Since this becomes the anode, the discharge tube becomes directional, making it unsuitable for AC power supply. This also applies to the embodiments described below.

Furthermore, in the case of the discharge tube 15 shown in FIG. 2B, the electrode stand 17 also serves as the anode side electrode, and unlike in FIG. 2A, small holes are not formed on the electrode surface.
Since the electrode also serves as the anode, the number of parts is reduced, which can be expected to be cost-effective, and the number of assembly steps is also reduced, making it easier to assemble.However, compared to electrodes with small holes, the effective surface area of the electrode capable of discharging is smaller. Therefore, due to the influence of electrode wear due to discharge, it is not very suitable for discharge tubes that are used continuously.

In addition, in any of the above embodiments, each anode side electrode stand 12
．． The IT is screwed onto each of the casings 14 and 16 through threaded threads 18 and 19 formed on the inner circumferential surface of each of the casings 14 and 16, so that the inert gas inside each discharge tube 10 and 15 does not leak. The screwed portion is sealed with a sealant. Further, the coefficient of thermal expansion of the electrode stand 12.degree. 17 is approximately equal to that of each of the casings 14.degree. 16.

The discharge tube 20.21 in FIGS. 3A and 3B is the second
This is a smaller version of the discharge tube shown in Figures A and 2B. That is, screw threads 24 and 25 are provided on the outer circumferential surface of one end of each casing 22 and 23, respectively, and each anode side electrode plate 26 formed in a substantially lid shape is inserted through the threads.
．． 27 is fitted onto the casing and screwed onto the casing so as to cover each cathode side electrode. In the case shown in FIG. 3A, a thin plate with holes is sandwiched between the anode side electrode plate 26 and the anode side end surface of the casing 22.

According to the embodiment described above, the length in the longitudinal direction of the casing can be made smaller, and each of the anode side electrode plates 26 and 27 fitted onto the casing covers a part of the cathode side electrode 6. , there is no change in voltage characteristics due to usage conditions, and in the case of FIG. 3A, since there is a perforated thin plate 28, the effective surface area of the electrode capable of discharging is increased, and the influence of electrode wear is reduced.

In each of the embodiments described above, the electrode stand is screwed onto both open ends of the discharge tube, and the screwed parts are sealed with a sealing material. The means for sealing is not limited to the above-mentioned embodiments.Hereinafter, embodiments using other sealing means will be described. In each of the following examples, a pair of electrodes are both of the perforated Rogowski type, and there is no directionality of the discharge tube itself, with one electrode being a cathode and the other electrode being an anode.

The discharge tube 29 shown in FIG. 4 has a casing 30 made of ceramics with metallization applied to the open end surface 31. Similarly to the above-mentioned embodiment, the electrodes 6 are forced into place by a metal ring 5. Attached electrode stand 3
With the flange portion 32a of No. 2 in close contact with the opening end surface 31, an airtight connection is performed using brazing or oxide solder 33. Also, one electrode stand 3
2 is attached with a filling pipe 34 for filling an inert gas such as nitrogen gas into the tube, and brazing 35 is also done between this filling pipe 34 and the electrode stand 32. The filling pipe 34 is configured to be sealed with a predetermined sealing material after gas is filled into the pipe.

Here, the above-mentioned brazing or oxide solder joints 33 and 35 are
It is preferable that it can withstand at least 300°C. In addition, a high temperature atmosphere is formed by the above bonding work, and the electrode stand 3
Since there is a risk that the electrode 6 attached to the H! ,N! It is necessary to carry out the process in an oxygen-free environment, such as in a forming gas mixed with the above, in a vacuum, or in an inert gas.

Further, in the case of this embodiment, it is particularly necessary to make the coefficients of thermal expansion of the electrode stand 32 and the casing 30 substantially equal to prevent cranking of the joint portion 33 due to heat cycles.

In the discharge tube 36 shown in FIG. 5, the electrode stand 38 that seals the open end of the casing 37 has a small area. The casing 37 is composed of a main body part 37a whose negative end is narrowed inward and whose other end is open, and a lid part 37b that fits into the open end of the main body part 37a. The main body portion 37a and the lid portion 37b are airtightly connected by an oxide solder 39 or the like.

Further, each opening 40 of the main body 37a and the lid 37b
The Rogowski type electrode 41 having a smaller diameter than those of the above-mentioned embodiments is inserted into the opening 40 so that a flange 41a formed at its base end engages with the peripheral edge of the opening 40. Then, metallizing is applied to the peripheral edge of the opening 40, and the flange 41a that engages with the peripheral edge is held between the electrode base 38, which is formed in a substantially lid shape, and brazing 42 is performed, thereby forming an electrode. The opening end of the casing 37 is sealed while maintaining conduction between the base 38 and the electrode 41.

Note that the coefficient of thermal expansion of the electrode stand 38 should be approximately the same as that of the casing 37, that each of the above bonding operations should be performed in an oxygen-free condition, and that the heat resistance temperature of each bonded portion should be the same as in the above embodiment. .

The discharge tube 43 shown in FIG. 6 also has a smaller area of the electrode stand 45 that seals the open end of the casing 44, similar to the above embodiment. An electrode 46 is attached to the electrode stand 45 by brazing with a Rogowski type electrode 46 fitted inside the boss portion 45a, and this electrode stand 45 is attached to the open end of the casing 44 by brazing. The casing 44 is hermetically sealed by an oxide solder 47.

Note that the casing 44 has a main body portion 44a and a lid portion 44b.
The electrode stand 45 has approximately the same coefficient of thermal expansion as the casing 44, the joining operation is performed in an oxygen-free condition, etc., which are the same as in the above embodiment.

Incidentally, in each of the embodiments described above, various electrodes are shown in which the tip portion is formed in a non-sharp shape and a large number of uneven portions are formed on at least the cathode side, and at least the cathode side is of a Rogowski type with holes. However, the electrode shape that has both the characteristics of an equal electric field and an unequal electric field is not limited to the perforated Rogowski type. below,
Electrode shapes other than the perforated Rogowski type having characteristics of both an equal electric field and an unequal electric field will be described. In each of the following examples, a pair of electrodes have the same shape, and the discharge tube itself has no directionality.

The discharge tube 48 shown in FIG. 7 has a pincushion formed by bundling a plurality of needle electrodes 51 to form an unequal electric field on a boss portion 50a of an electrode stand 50 that seals the open end of a casing 49. The electrodes 52 are fitted inside, and the tips 51a of each needle electrode 51 are aligned with the virtual plane 5 in order to form an equal electric field.
It was designed to be located above 3.

In this way, compared to the perforated Rogowski type electrode, the characteristics of the unequal electric field can be further strengthened, and the discharge voltage (1) can be made more stable.

Further, the virtual plane 53 is made into a Rogowski shape, and the tip 51 of each needle electrode 51 is placed on this Rogowski type plate imaginary plane.
A more preferable electrode can be obtained by arranging the position a.

Further, in the discharge tube 54 shown in FIG. 8, a plurality of recesses 58 are formed on the inner surface 56a of the electrode stand 56, which seals the open end of the casing 55, on the tip surface 57a to form an unequal electric field. A substantially pipe-shaped electrode 57 is fixed thereto, and the tip surface 57a is positioned within a virtual plane 59 to form a uniform electric field.

Even in this case, the characteristics of the unequal electric field can be further strengthened, and the discharge voltage (2) can be stabilized, and the tip surface 57a is located within the virtual plane 59 formed as a Rogowski type. By doing so, a more preferable electrode can be obtained.

In each of the embodiments described above, nitrogen gas was used as an example of an inert gas to be filled in the discharge tube, but this nitrogen gas is especially suitable for series gap ignition devices such as automobile engines. By changing the gas to air, argon, helium, etc., the discharge voltage of the discharge tube can be changed from several tens of kilovolts to several tens of volts depending on the gas enclosed. Therefore, the electrode structure of the present invention can be applied not only to series gap igniters but also to various types of discharge tubes, such as discharge tubes for strobes and discharge tubes used in lightning arresters for telephone exchanges and the like.

Further, the Rogowski type electrode shown in the above embodiment is an example of a substantially flat plate electrode shape with a non-sharp tip, and is not limited to this shape. For example, the electrode tip has a large radius. The same effect can be obtained even if it is formed into a substantially hemispherical shape.

〔Effect of the invention〕

As is clear from the above description, in the present invention, the tips of the pair of electrodes that are substantially opposed to each other are formed into non-sharp shapes, and at least the surface of the cathode side electrode is formed with a large number of uneven parts. A stable high discharge voltage can be obtained from the beginning of discharge with a narrow electrode spacing.

Furthermore, since the electrode surface area is large, electrode wear is dispersed and the durability is excellent. Furthermore, since the electrode spacing is narrow, the discharge sustaining voltage is low and energy loss is reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the discharge tube according to the present invention, FIGS. 2A to 3B are sectional views showing partially modified embodiments of the above embodiment, and FIGS. 4 to 8 is a sectional view showing another embodiment, FIG. 9 is a sectional view showing a conventional discharge tube, FIG. 1θ is a sectional view showing an ignition device with a series gap using the above discharge tube, and FIG. A circuit diagram of the ignition device, and FIG. 12 is a diagram showing the voltage characteristics of the discharge tube. 1.10, 15, 20, 21, 29, 36, 43.48
．． ．． 54...discharge tube, 2,14,16,22°23.
30, 37, 44, 49, 55...Casing, 4,
12, 17. 26, 27, 32, 3B. 45.50.56... Electrode stand, 5... Metal ring, 6.41.46... Rogowski type electrode, 7,13
... Small hole, 9 ... Sealing material, 52 ... Needle electrode, 5
7... Pipe type electrode, C... Ignition device with series gap, S... Series gap, P... Spark plug, ■1... Discharge voltage, ■2... Discharge sustaining voltage. Figure 1b Figure 2A Figure 2B Figure 3A Figure 1Q Figure 7 Figure 8 Figure 12

Claims (7)

[Claims] (1) In a discharge tube in which a voltage is applied between a pair of electrodes and a discharge is caused between an anode side electrode and a cathode side electrode, the ends of the pair of electrodes that are substantially opposed to each other are formed in a non-sharp shape. A discharge tube characterized in that a large number of uneven portions are formed on at least the surface of the cathode side electrode. (2) The discharge tube according to claim 1, wherein the plurality of uneven portions are formed from a large number of holes. (3) The non-sharp tip of the cathode side electrode has a plane surface that faces substantially opposite the anode side electrode, and a peripheral edge of the surface is formed into a curved shape bent away from the anode side electrode. Claim (1) or (2) characterized in that
The discharge tube described in . (4) According to claim (1), the cathode side electrode having a large number of uneven portions at least on its surface is formed as a pincushion electrode bundled so that the tips of the needles are located on a virtual plane. The discharge tube described. (5) The above-mentioned cathode side electrode having a large number of uneven portions on at least its surface is formed as a pipe-shaped electrode in which the end surface of the pipe is located within a virtual plane, and the uneven portion is formed on the end surface over the entire circumference. Characteristic discharge tube. (6) The cathode side electrode has at least two parts: an electrode stand that seals the open end of the discharge tube casing and has approximately the same coefficient of thermal expansion as the discharge tube casing, and an electrode that is attached to this electrode stand. The discharge tube according to any one of claims (1) to (5), characterized in that it is comprised of: (7) The anode side electrode is formed such that an anode side electrode plate fitted onto the casing of the discharge tube covers the cathode side electrode. Discharge tube described in Crab.