JPH0697627B2 - Discharge tube and ignition device with series gap using the discharge tube - Google Patents

Description

TECHNICAL FIELD The present invention relates to a discharge tube suitable for an ignition device with a series gap such as an automobile engine, and an ignition device with a series gap using the discharge tube.

[Conventional technology]

In recent years, as shown in FIG. 4, a so-called series gap S is provided in series with the spark plug P to prevent smoldering of the spark plug P due to adhesion of carbon or the like to keep the ignition timing constant. The ignition mounting I is known (see Japanese Patent Publication No. 51-32180), and it is considered to form the series gap S by a so-called discharge tube.

As shown in FIG. 5, the automobile series gap igniter I has a high voltage cable 1 connected to the power supply side, and
A plug cap 2 that is detachably fitted to the spark plug P is attached, and a connection terminal 4 engageable with a terminal 3 of the spark plug P is provided in the plug cap 2.
A power supply terminal 5 connected to an end of the high-voltage cable 1 is arranged so as to face it, and a discharge tube T that forms the series gap S between the terminals 4 and 5 is incorporated. In this discharge tube T, an open end of an insulating tube 6 as a sealing tube made of ceramics or the like is sealed with a pair of electrodes composed of a discharge electrode section 7 and an electrode plate 8, and a predetermined gap is formed inside the discharge tube. An active gas is sealed in, and a sufficient discharge space is formed around the pair of discharge electrode portions 7, 7 forming the series gap S. The discharge gas is formed on the electrode plate 8. It is configured to be connected to and supported by the terminals 4 and 5 via the support fitting 9. The ignition device I having the above-described configuration is embedded in the recess 11 formed in the cylinder head or the cylinder head cover 10 of the engine, and is fitted to the spark plug P screwed to the engine side. . Reference numeral 12 in the drawing denotes a metal pipe for guiding the ignition device I and at the same time protecting the ignition device I from contamination by engine oil.

[Problems to be Solved by the Invention]

However, in the conventional ignition device I with a series gap, a slight gap 13 is inevitably formed between the built-in discharge tube T and the plug cap 2 around the discharge tube T, and the discharge tube T is ignited. The ignition device I is in a state of floating with respect to the ground (earth) by the amount of the plug P, and the ignition device I in the above-described state is the cylinder head or the cylinder head cover.
Since the discharge tube T and the metal pipe 12 at the ground potential are guided by the metal pipe 12 having the same potential as the ground potential of 10 and the metal pipe 12 at the ground potential is close to each other, an electrode for sealing both ends of the discharge tube T is formed. A so-called corona discharge D may occur from the edge portion of the electrode plate 8 which is a part toward the metal pipe 12 having the ground potential, and when the discharge tube T repeatedly discharges tens of thousands of times, the corona discharge D causes the corona discharge D. The plug cap 2 around the discharge tube T may deteriorate, and in the worst case, the plug cap 2 may be dielectrically broken and a predetermined voltage may not be applied to the spark plug P, resulting in misfire.

Therefore, it is conceivable that the entire electrode portions at both ends of the discharge tube T where the corona discharge D may occur are covered with the electrically insulating material, but both end portions of the discharge tube T are both covered with the electrically insulating material. And the discharge tube T itself becomes larger, and as a result, the ignition device with a series gap having the discharge tube T built therein becomes larger, and both ends of the discharge tube T are covered with an electrically insulating material. Moreover, there is also a problem that the manufacturing cost increases.

The present invention has been made in view of the above-mentioned points, and prevents so-called corona discharge generated from the discharge tube due to a potential difference generated between an electric element and the like arranged around the discharge tube, and the The present invention provides a discharge tube capable of reducing the size of the entire discharge tube and also reducing the manufacturing cost thereof, which is designed to prevent deterioration of the assembly located therein, and uses the discharge tube to provide an engine. It is an object of the present invention to provide an ignition device with a series gap capable of achieving higher performance.

[Means for Solving the Problems]

In order to achieve the above object, the discharge tube according to the present invention is such that both end openings of the insulating tube are sealed with a pair of electrode parts facing each other.
In a discharge tube in which a high-pressure inert gas is sealed in the insulating tube, the inner peripheral surface of the insulating tube is formed into a substantially conical surface shape, and the discharge space in the insulating tube is formed into a substantially conical shape. The insulating tube opening on the bottom side of the space is sealed with an electrode plate on which the discharge electrode section is provided, and the insulating tube opening on the apex side of the conical discharge space has an outer diameter approximately equal to that of the opening. It is characterized in that it has the same diameter and is sealed by rod-shaped electrode portions that face the discharge electrode portion and face each other via a discharge gap.

Further, on the outer peripheral surface of the end portion of the insulating tube on the electrode plate side, a conductive member having the same potential as the electrode plate surrounding the discharge electrode portion of the electrode plate is provided, or the discharge electrode portion of the electrode plate and the rod-shaped electrode portion. The discharge electrode portion is formed so as to project on the electrode plate so that the discharge gap of 1 is close to the electrode plate side.

Further, the ignition device with a series gap according to the present invention incorporates a discharge tube that forms a series gap in which one end is connected to the center electrode side of the spark plug and the other end is connected to the high-voltage cable side extending from the power supply side. In the ignition device with a series gap consisting of, in the discharge tube, the inner peripheral surface of the insulating tube is formed into a substantially conical surface shape, and the discharge space in the insulating tube is formed into a substantially conical shape. The insulating tube opening is sealed with an electrode plate on which the discharge electrode section is provided, and the insulating tube opening on the apex side of the conical discharge space has an outer diameter substantially equal to that of the opening, An electrode surrounding the discharge electrode portion of the electrode plate on the outer peripheral surface of the end portion of the insulating tube of the discharge tube on the electrode plate side of the discharge tube sealed with the rod-shaped electrode portion facing each other through the discharge gap. Provide a conductive member with the same potential as the plate A discharge tube or a discharge tube in which the discharge electrode section is formed on the electrode plate so that the discharge gap between the discharge electrode section of the electrode plate of the discharge tube and the rod-shaped electrode section is close to the electrode plate side is used. The discharge tube is incorporated so that the electrode plate side of these discharge tubes serves as the cathode.

[Action]

According to the discharge tube of the present invention, the edge portion is formed only on the electrode plate that seals the insulating tube opening on the bottom side of the conical discharge space, and the insulating tube opening on the apex side of the conical discharge space is sealed. An edge is not formed in the rod-shaped electrode portion that stops, so-called corona discharge generated from the discharge tube due to the potential difference between the rod-shaped electrode portion and the electric elements arranged around the discharge tube is mainly the electrode plate portion. It occurs only in the above, and hardly occurs in the rod-shaped electrode portion. Therefore, it is sufficient to take the above corona discharge prevention measures only on the electrode plate side, and it is not necessary to take corona discharge prevention measures for both electrode portions at both ends of the discharge tube as in the conventional case.

Further, according to the ignition device with a series gap according to the present invention, in the discharge tube incorporated as the series gap, the inner peripheral surface of the insulating tube is formed into a substantially conical surface shape, and the discharge space in the insulating tube is formed into a substantially conical shape. The insulating tube opening on the bottom side of the conical discharge space is sealed with an electrode plate on which the discharge electrode section is provided, and the insulating tube opening on the apex side of the conical discharge space is connected to this opening and the outside. The diameter is almost the same, and the discharge tube is sealed with rod-shaped electrode parts facing each other through a discharge gap with the discharge electrode part, or on the outer peripheral surface of the electrode plate side end of the insulating tube of the discharge tube, Since a discharge tube provided with a conductive member having the same potential as the electrode plate surrounding the discharge electrode part of the electrode plate was used so that the electrode plate side became the cathode, almost corona discharge occurred at the rod-shaped electrode part of the discharge tube. I will not do it, corona release in this part Deterioration of the assembly due to be eliminated. In addition, when a negative voltage is applied from the high voltage cable side to the electrode plate side when the conductive member is provided on the electrode plate side, the conductive member prevents the influence of the surrounding electric field and prevents the cathode inside the discharge tube. The electric field near the side can be stabilized, and the change in the discharge voltage characteristic of the discharge tube is eliminated, so that the overall deviation of the ignition timing can be prevented and the performance of the engine can be improved.

Further, as in the example of FIG. 2, in the discharge tube in which the electrode projections on the electrode plate side are further reduced so that the discharge occurs very close to the electrode plate side, even if no conductive member is specially provided, It is possible to obtain almost the same effect.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3, and the same reference numerals will be used for the same portions as those in the related art.

FIG. 1 shows an embodiment of a discharge tube according to the present invention, in which a hollow cylindrical insulating tube 6 as a sealing tube made of ceramics or the like has a substantially conical shape with a sufficient size. Discharge space 14 is formed, and the discharge space 14 is formed at one end of the insulating tube 6 on the bottom side of the conical discharge space 14.
And a small diameter opening 16 is formed at the other end of the insulating tube 6 on the apex side of the conical discharge space 14. The end surface of the insulating tube 6 on the side of the large-diameter opening 15 is subjected to metallizing treatment or the like, and by brazing or the like, the electrode plate 8 having substantially the same outer diameter as the insulating tube 6 is formed.
It is designed to be sealed. In addition, the electrode plate 8
Is formed with a supporting metal fitting 9 connected to and supported by a power supply terminal of an ignition device with a series gap (not shown) on its outer end surface, and a discharge electrode portion formed on its inner end surface to be short and facing the discharge space 14. 7 is formed, and the large diameter opening 15 of the insulating tube 6 is sealed by a so-called flanged electrode 17 composed of the electrode plate 8 and the discharge electrode portion 7. Further, a metallized band 18 having a predetermined width as a conductive member is formed on the outer peripheral surface of the insulating tube 6 so as to surround the discharge electrode portion 7 of the collared electrode 17, and the metallized band 18 is formed on the electrode plate. 8 is electrically connected.

In addition, the small-diameter opening 16 of the insulating pipe 6 has the small-diameter opening 16
And a substantially equal-diameter electrode 19 as a rod-shaped electrode portion having an outer diameter of approximately the same diameter is fitted and inserted, and the small-diameter opening 16 is sealed by this electrode 19, and the fitted electrode is The tip portion of 19 acts as a discharge electrode portion and extends to near the short discharge electrode portion 7 located in the discharge space 14 to form a predetermined series gap. The end portion of the substantially equal-diameter electrode 19 projecting from the insulating tube 6 is formed as a support metal fitting 9 which is connected to and supported by a connection terminal of an ignition device with a series gap (not shown).
An inert gas such as argon is enclosed in the discharge space 14 of the insulating tube 6 by an enclosed pipe (not shown) coaxially arranged in the chamber 19.

In this embodiment, a high voltage negative voltage is applied to one side of the collar electrode 17 composed of the electrode plate 8 and the discharge electrode portion 7, and the other side of the approximately equal-diameter electrode 19 is connected to the ground side. Tube T is used. Therefore, in this usage state, the one electrode 17 side serves as a cathode (cathode) from which electrons are emitted by a discharge phenomenon, and the other electrode 19 side serves as an anode (anode).

Therefore, in this embodiment, the edge portion is formed only on the electrode plate 8 portion as the flange portion of the collared electrode 17 that seals the large diameter opening 15, and the substantially equal diameter electrode that seals the small diameter opening 16 is formed. 19
Since the above-mentioned collar portion is not formed in the portion and an edge portion due to this collar portion is not formed, so-called corona discharge generated from the discharge tube T due to a potential difference between the discharge tube T and an electric element or the like arranged around the discharge tube T is generated. It occurs only in the electrode plate 8 portion and almost never in the substantially equal diameter electrode 19 portion,
The assembly located around the end on the 19 side will not deteriorate due to corona discharge. In addition, the above-mentioned collared electrode 17
Since it suffices to take corona discharge prevention measures by covering only the side with an electrically insulating material, it is not necessary to take corona discharge prevention measures on both electrode parts of the discharge tube as in the conventional case. The entire discharge tube T can be downsized, and the manufacturing cost of the discharge tube T itself can be suppressed. Further, since the substantially conical discharge space 14 is formed in the insulating tube 6 and the small diameter opening 16 connected to this discharge space 14 is sealed by the substantially equal diameter electrode 19, the end of the insulating tube 6 on the side of the small diameter opening 16 is closed. The inner peripheral surface of the portion becomes tapered, and the thickness of the portion becomes thicker, and the electrode is sealed by the substantially equal-diameter electrode 19. In other words, the strength of the end portion of the insulating tube 6 that holds the approximately equal-diameter electrode 19 can be made sufficient.

Further, in the present embodiment, the discharge tube T is surrounded by the discharge electrode portion 7 of the collared electrode 17 used as the cathode side.
A metallized band 18 serving as a conductive member is provided on the outer peripheral surface of the metallized band 18.
Since the discharge electrode portion 7 and the metallized band 18 have the same electric potential, the metallized band 18 acts as a so-called back electrode, and the discharge tube portion 7 and the metallized band 18 are electrically connected to each other. Even when an electric element or the like having a potential of is located and a predetermined electric field is formed around the electric element or the like, the vicinity of the cathode side inside the discharge tube T is not disturbed, and the discharge electrode portion 7 forms a stable electric field between the opposing electrodes 19 of substantially equal diameter. As a result, a stable discharge phenomenon can be obtained, and the discharge voltage characteristic of the discharge tube T can be stabilized.

FIG. 2 shows another embodiment of the discharge tube according to the present invention, in which the insulating tube 6 itself forming a predetermined discharge space 14 is formed in a substantially conical shape, and an opening 15 having a large diameter is formed at one end thereof. When is formed, an opening 16 having a small diameter is formed at the other end. An electrode plate 8 having a size corresponding to the outer diameter of the end of the insulating tube 6 on the side of the opening 15 is sealed in the large-diameter opening 15 as in the above embodiment. Is formed with the support fitting 9, and the inner end surface of the support fitting 9 is
The discharge electrode portion 7 is formed so as to be shorter than the discharge electrode portion 7 of the above-mentioned embodiment and hardly or not at all protrude from the electrode plate 8. The large-diameter opening 15 of the insulating tube 6 is sealed by a so-called collared electrode 17 composed of the electrode plate 8 and the discharge electrode portion 7.

In addition, the small-diameter opening 16 of the insulating pipe 6 has the small-diameter opening 16
A substantially equal-diameter electrode 19 having substantially the same diameter as that of the electrode 19 is fitted and the small-diameter opening 156 is sealed by the electrode 19, and the electrode 19 formed longer than that of the fitted embodiment.
Of the discharge electrode portion 7 acts as a discharge electrode portion.
And a predetermined series gap is formed therebetween. Further, an end portion of the substantially equal-diameter electrode 19 projecting from the insulating tube 6 is formed as a support fitting 9, and the electrode
As in the above embodiment, an inert gas such as argon is enclosed in the discharge space 14 of the insulating tube 6 by an enclosed pipe (not shown) coaxially arranged in the chamber 19.

Further, the discharge tube T is used so that a high voltage negative voltage is applied to the flanged electrode 17 side and the other substantially equal-diameter electrode 19 side is the ground side. It becomes the emitted cathode (cathode) and the other electrode
The point that the 19th side serves as an anode (anode) is also the same as in the above embodiment.

Therefore, also in this embodiment, the edge portion is formed only on the electrode plate 8 portion as the flange portion of the collared electrode 17 for sealing the large diameter opening 15, and the substantially equal diameter electrode for sealing the small diameter opening 16 is formed. 19
Since the above-mentioned collar portion is not formed in the portion and an edge portion due to this collar portion is not formed, so-called corona discharge generated from the discharge tube T due to a potential difference between the discharge tube T and an electric element or the like arranged around the discharge tube T is generated. Almost no generation occurs in the above-mentioned approximately equal-diameter electrode 19 portion, and the assembly located around this portion does not deteriorate due to corona discharge. Also, since it is only necessary to take measures to prevent corona discharge by covering only the side of the flanged electrode 17 where corona discharge occurs with an electrically insulating material, it is necessary to take measures to prevent corona discharge on both electrode parts of the discharge tube as in the past. Since it is not necessary to apply it, the entire discharge tube T can be made smaller than the conventional one, and the manufacturing cost of the discharge tube T itself can be suppressed.

Further, since the discharge electrode portion 7 on the side of the flanged electrode 17 is formed so as to hardly or not at all protrude from the electrode plate 8 used as the cathode, the outer circumference of the insulating tube 6 as in the above-described embodiment. Even if the conductive member (metallized band) 18 as a so-called back electrode is not provided on the surface, the electrode plate 8 acts on the discharge electrode portion 7 as a conductive member as a back electrode. The cost can be reduced more than that of the above-described embodiment because there is no such amount. further,
Depending on the size of the discharge tube, the insulation distance along the outer surface of the insulating tube 6 from the conductive member on the cathode side to the electrode on the anode side is different from that of the above-described embodiment in which the insulating tube 6 is provided with the conductive member 18 as a back electrode. It may become long and then, at that time,
It is possible to prevent so-called creeping discharge that may occur along the outer surface of the insulating tube 6.

Further, since the insulating tube 6, that is, the outer shape of the discharge tube T is formed in a substantially conical shape as described above, when the discharge tube T is incorporated in the ignition device with a series gap, the flanged electrode 17 is used.
It is possible to determine at a glance that the large-diameter end side sealed with is the cathode, and the small-diameter end side sealed with the substantially equal-diameter electrode 19 is the anode. You can prevent mistakes.

FIG. 3 shows an embodiment of the ignition device 1 with a series gap using the above-described discharge tube T according to the present invention.
Inside the plug cap 2, one is sealed with the collared electrode 17 and the other is sealed with a substantially equal-diameter electrode 19, and a conductive member 18 as a back electrode covering the collared electrode side 17 is provided. ,
The discharge tube T shown in FIG. 1 is incorporated so that the one without the conductive member 18 is connected to the side of the center electrode of the ignition plug P on the side of the high voltage cable 1 extending from the high voltage coil that generates the discharge voltage. Has been done. And the above-mentioned collared electrode
The side 17 is used as a cathode (cathode) from which electrons are emitted by a discharge phenomenon, and the side 19 having substantially the same diameter is used as an anode.

In this embodiment, a so-called corona discharge D is generated only between the flanged electrode 17 of the discharge tube T and the metal pipe 12 which is at the ground potential, and almost no corona discharge is generated at the substantially equal-diameter electrode 19. Therefore, if only the flanged electrode 17 portion is covered with an electrically insulating material or the like, it is located around the discharge tube such as the plug cap 2 due to corona discharge at the approximately equal-diameter electrode 19 portion. The deterioration of the assembly can be prevented.

Further, since the conductive member 18 as a back electrode is provided on the side of the collar electrode 17 serving as a cathode, the electric field strength around the discharge tube T is changed by the presence of the metal pipe 12 at the ground potential. However, the conductive member 18 can prevent the influence of the surrounding electric field and stabilize the electric field in the vicinity of the cathode side inside the discharge tube T, and by eliminating the change in the discharge voltage characteristic of the discharge tube T, the entire ignition timing can be improved. It is possible to improve the performance of the engine by preventing the deviation from occurring.

Reference numeral 20 is an electrically insulating mold material such as a resin injected into the plug cap 2 in order to prevent corona discharge D generated in the flanged electrode 17 portion. Further, the present invention is not limited to the above-described embodiment, but various modifications can be made. For example, the conductive member 18 provided on the outer peripheral surface of the discharge tube T is formed by the metallizing method. Any material having conductivity, such as a conductive paint or a metal foil, may be installed at a place other than the outer peripheral surface, for example, embedded in the wall of the plug cap 2.

〔The invention's effect〕

As described above, in the discharge tube according to the present invention, the so-called corona discharge generated from the discharge tube due to the potential difference between the discharge tube and the electric elements arranged around the discharge tube is generated only in the electrode plate portion, It hardly occurs at the electrode part, and the above corona discharge prevention measures only need to be taken on the electrode plate side, and it is not necessary to take corona discharge prevention measures on both electrode parts of the discharge tube as in the past. Compared with the above, there is an effect that the entire discharge tube can be downsized and the manufacturing cost of the discharge tube itself can be suppressed.

Further, the ignition device with a series gap according to the present invention causes almost no corona discharge at the rod-shaped electrode portion of the discharge tube incorporated as a series gap, and the deterioration of the assembly due to the corona discharge at this portion is eliminated. When a conductive member is provided on the electrode plate side and a negative voltage is applied from the high voltage cable side to the electrode plate side, the conductive member prevents the influence of the surrounding electric field and prevents the influence of the vicinity of the cathode side inside the discharge tube. Can stabilize the electric field,
By eliminating the change in the discharge voltage characteristic of the discharge tube, it is possible to prevent the overall shift of the ignition timing and to achieve higher performance of the engine.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a discharge tube according to the present invention, FIG. 2 is a perspective view showing another embodiment of the discharge tube, and FIG. 3 is a series gap ignition device according to the present invention. FIG. 4 is a sectional view showing an embodiment, FIG. 4 is a circuit diagram of an ignition device with a series gap, and FIG. 5 is a sectional view showing a conventional ignition device with a series gap. T ... discharge tube, P ... spark plug, S ... series gap,
I ... Ignition device with series gap, D ... Corona discharge, 2
... Plug cap, 6 ... Insulation tube, 7 ... Discharge electrode part, 8 ...
Electrode plate, 9 ... Supporting metal fitting, 12 ... Metal pipe, 14 ... Discharge space, 15 ... Large diameter opening, 16 ... Small diameter opening, 17 ... Collared electrode, 18 ...
Conductive member (metallized band), 19 ... Approximately equal diameter electrode, 20 ... Electrically insulating material.

Claims (4)

[Claims] 1. A discharge tube in which opening portions at both ends of an insulating tube are sealed by a pair of electrode portions facing each other, and a high-pressure inert gas is sealed in the insulating tube. Is formed into a substantially conical surface shape so that the discharge space in the insulating tube is formed into a substantially conical shape, and the insulating tube opening on the bottom side of this conical discharge space is sealed with an electrode plate provided with a discharge electrode portion. Together with the insulating tube opening on the apex side of the conical discharge space, the outer diameter of this opening is almost the same,
A discharge tube characterized by being sealed with rod-shaped electrode portions facing each other through the discharge electrode portion via a discharge gap. 2. The discharge according to claim 1, wherein a conductive member having the same potential as the electrode plate surrounding the discharge electrode portion of the electrode plate is provided on the outer peripheral surface of the end portion of the insulating tube on the electrode plate side. tube. 3. The discharge electrode section is formed on the electrode plate so that the discharge gap between the discharge electrode section of the electrode plate and the rod-shaped electrode section is close to the electrode plate side. The discharge tube according to 1. 4. An ignition device with a series gap, comprising a discharge tube having one end connected to a center electrode side of an ignition plug and the other end connected to a high voltage cable side extending from a power supply side to form a series gap. An ignition device with a series gap, characterized in that the discharge tube according to claim 1, 2 or 3 is used as the discharge tube, and the discharge tube is incorporated so that an electrode plate side of the discharge tube serves as a cathode. .