CA2019909A1 - Gas-filled discharge tube - Google Patents
Gas-filled discharge tubeInfo
- Publication number
- CA2019909A1 CA2019909A1 CA002019909A CA2019909A CA2019909A1 CA 2019909 A1 CA2019909 A1 CA 2019909A1 CA 002019909 A CA002019909 A CA 002019909A CA 2019909 A CA2019909 A CA 2019909A CA 2019909 A1 CA2019909 A1 CA 2019909A1
- Authority
- CA
- Canada
- Prior art keywords
- tube
- discharge
- gas
- discharge tube
- openings
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000007789 gas Substances 0.000 claims abstract description 24
- 239000011261 inert gas Substances 0.000 claims abstract description 7
- 239000012777 electrically insulating material Substances 0.000 claims description 5
- 238000010276 construction Methods 0.000 abstract description 8
- 238000010304 firing Methods 0.000 abstract description 5
- 238000007789 sealing Methods 0.000 abstract description 2
- 230000002159 abnormal effect Effects 0.000 description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 239000011521 glass Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- PWKWDCOTNGQLID-UHFFFAOYSA-N [N].[Ar] Chemical compound [N].[Ar] PWKWDCOTNGQLID-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000565 sealant Substances 0.000 description 1
- 238000005476 soldering Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J17/00—Gas-filled discharge tubes with solid cathode
- H01J17/38—Cold-cathode tubes
- H01J17/40—Cold-cathode tubes with one cathode and one anode, e.g. glow tubes, tuning-indicator glow tubes, voltage-stabiliser tubes, voltage-indicator tubes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J17/00—Gas-filled discharge tubes with solid cathode
- H01J17/02—Details
- H01J17/18—Seals between parts of vessels; Seals for leading-in conductors; Leading-in conductors
- H01J17/186—Seals between leading-in conductors and vessel
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T1/00—Details of spark gaps
Landscapes
- Ignition Installations For Internal Combustion Engines (AREA)
- Spark Plugs (AREA)
Abstract
A gas-filled discharge tube of a compact construction for use as a series gap in the ignition system of an automotive spark-ignition engine and the like. The gas-filled discharge tube comprises an insulating tube unit having a tube provided with openings of a diameter smaller than the inside diameter thereof in the opposite ends thereof, a pair of electrode bases closely attached to the opposite ends of the tube so as to seal the openings, a pair of perforated discharge electrodes attached respectively to the opposite inner surfaces of the electrode bases to form a series gap, and an inert gas filling the tube. Since the diameter of the electrode bases sealing the comparatively small openings is comparatively small, the electrode bases of a comparatively small diameter may be used. Thus, the capacitance between the electrode bases, hence the capacitance of the gas-filled discharge tube, is comparatively small, which enables the firing potential of the gas-filled discharge tube to be increased without increasing the capacitance of the same.
Description
The present invention relates to a gas-filled discharge tube suitable for use in the ignition system with a series gap of an automotive engine and the like.
The ignition system with a series gap has a discharge tube having a predetermined capacitance and connected in series to a spark plug to prevent the soothing of the spark plug with carbon. Such an ignition system with a series gap disclosed in Japanese Utility Model Laid-open (Kokai) No. 63-lnl486 has a circuit configuration. This known ignition system comprises an ignition coil, a discharge tube, and a spark plug. Each of the discharge tube and the spark plus has a capacitance. The electric potential of the center electrode of the spark plug, i.e., the electric potential of a first predetermined point increases in proportion to the ratio between the respective capacitances of the discharge tube and the spark plug when the voltage V applied across the discharge tube, i.e. the electric potential of another predetermined point, is increased. Discharge occurs in the discharge tube when the electric potential of a first point reaches a sufficiently high level, and then the electric potential of the another predetermined point drops sharply and the electric potential of the first predetermined point increases sharply.
If the circumference of the center electrode of the spark plug is soothed with a carbon layer, it is possible that a leakage current flows through the carbon layer to a portion of the center electrode deep from the extremity. When the center electrode of the spark plug,~3)is in such a soothed condition, the potential of the deep portion of the cen-ter electrode, i.e. the potential of a second predetermined point, increases with the potential of the center electrode with a delay as the potential of the center electrode is increased sharply by the discharge of , .
. ~
' ; . ' ',~ ' .
,; . . :
the discharge tube. Suppose that the firing potential of the center electrode is 8 kV. Then, the firing potential of the deep portion is about 6 kV, because the gap between the deep portion and the casing is smaller than that between the center electrode and the opposite electrode. Consequently, a normal spark discharge is passed between the center elec-trode and the opposite electrode at the point of intersec-tion of a line corresponding to 8 kV and a curve repre-senting the variation of the potential of the center electrode, and an abnormal spark discharge is passed between the deep portion and the casing at the point of intersection of a line corresponding to 6 kV and the curve representing the variation of the potential of the deep portion.
~ However, the normal spark discharge occurs earlier by a - 15 predetermined time between the center electrode and the opposite electrode than the abnormal spark discharge, and hence the spark plug may not be soothed due to the abnormal spark discharge.
The conventional discharge tube comprises a tube formed of an electrically insulating material, such as a ceramic, and having opposite open ends, a pair of electrode bases closely fitted respectively in the opposite ends of the tube, and a pair of discharge electrodes held on the electrode bases within the tube. The tube is filled with an inert gas. The sum of the capacitance between the pair of discharge electrodes and the capacitance between the pair of electrode bases is the capacitance of the discharge tube In such an ignition system, it is desired to employ a compact discharge tube to enable the plug cap attached to the extremity of the high-tension cable to be formed in a compact construction. When the length of the discharge tube of a construction is reduced to increase the capacitance of the discharge tube and such a discharge tube ; ~, ., . ' ': ' , having a comparatively large capacitance is employed in the ignition system and the same spark plug having the same capacitance is used, the potential of the center electrode and the potential of the deep portion of the spark plug increase according to the increase in the capacitance of the discharge tube. Consequently, a time interval between the point of occurrence of the normal spark discharge between the center electrode and the opposite electrode, and the point of occurrence of the abnormal spark discharge becomes very short and hence it is a matter of probability that which of the normal spark discharge and the abnormal spark discharge will occur first. Therefore, increase in the capacitance of the discharge tube entails increase in the possibility of the abnormal spark discharge soothing the spark plug.
Accordingly, it is an object of the present invention to provide a gas-filled discharge tube of a compact construction, having an appropriate capacitance which will not cause soothing the spark plug.
According to the present invention, there is provided a gas-filled discharge tube comprising an insulating tube unit having a tube formed of an electrically insulating material and having openings in the opposite ends thereof, a pair of electrode bases closely attached to the opposite ends of the tube so as to close the openings, respectively, a pair of discharge electrodes attached respectively to opposite inner surfaces of the electrode bases to form a series gap, and an inert gas filling the insulating tube unit, wherein the diameter of peripheries of the openings covered with the electrode bases is smaller than the inside diameter of the tube.
.
.
.
Since the diameter of the portions of the opposite ends of the tube provided with the openings closed by the electrode bases is smaller -.
..
. ?
than that of other portions, the diame~er, hence the area, of the electrode bases may be comparatively small, so that the capacitance between the electrode bases, hence the capacitance of the sas-filled discharge tube, is comparatively small and hence the gas-filled dis-charge tube can be formed in a compact construction without excessively increasing the capacitance.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present invention will become more apparent from the following descrip-tion taken in connection with the accompanying drawings, in which:
Figure 1 is a longitudinal sectional view of a gas-filled dis-charge tube in a first embodiment according to the present invention;
Figure 2 is a longitudinal sectional view of a gas-filled dis-charge tube in a second embodiment according to the present invention;
Figure 3 is a circuit diagram of an ignition system with a series gap;
Figure 4 is a graph showing potential variations at different points in the ignition system of Fig. 3;
Figure 5 is an enlarged fragmentary sectional view of the ex-tremity of a spark plug; and Figure 6 is a longitudinal sectional view of a conventional discharge tube.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
.
'', ; '' Gas-filled discharge tubes embodying the present invention will be described hereinafter with reference to Figs. 1 and 2, in which parts like or corresponding to those of the conventional discharge tube previously described with reference to Figs. 3 to 6 will be denoted by the same reference characters.
First Embodiment Referring to Fig. 1, a gas-filled discharge tube 2 comprises an insulating tube unit 7 formed of an electrically insulating material, such as alumina ceramic, steatite or crystallized glass, and provided with openings 10 and 12 of the same diameter R2 at its opposite ends, a pair of metallic electrode bases 9 attached to the opposite ends of the insulating tube unit 7 so as to close the openings, respectively, a pair of discharge electrodes 8 projecting from the opposite inner surfaces of the electrode bases 9 so as to form a series gap, and an inert gas, such as argon gas or an argon-nitrogen mixed gas, filling the insulating tube unit 7.
The insulating tube unit 7 consists of a tube 11 and an end cap 13 fitted in one end of the tube ll and provided with an opening 12.
The other end of the insulating tube 7 is reduced to form the opening 10 having a diameter R2 smaller than the diameter Rl of the open end of the tube 11 closed by the end cap 13. The tube ll and the end cap 13 are joined together with glass frit 14 or the like to form the insulating tube unit 7 provided with the openings 10 and 12 of the same diameter R2 smaller than the diameter Rl of the open end of the tube 11, i.e., the inside diameter of the tube ll.
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The pair of discharge electrodes 8 are inserted through the openings 10 and 12 in the insulating tube unit 7 so as to form a dis-charge gap between the opposite top surfaces thereof. Each of the discharge electrodes 8 is of a so-called Rogowskii type having a flat top surface 8a having a curved periphery 8b, and provided with a number of small holes. Flanges 8c formed around the base ends of -the discharge electrodes 8 are seated on the peripheries of the openings 10 and 12, respectively. The electrode bases 9 have the shape of a cap and are jointed to the peripheries of the openings 10 and 12 so as to hold the flanges 8c of the discharge electrodes 8 on the peripheries of the openings 10 and 12 and to close the openings 10 and 12, respectively.
The openings 10 and 12 may be sealed by soldering the flanges 8c of the discharge electrodes 8 held by the electrode bases 9 to the metallized surfaces 15 of the peripheries of the openings 10 and 12, respectively.
A yas-charging pipe 16 connected to the electrode base 9 is sealed with a sealant after charging the insulating tube unit 7 with the inert gas.
Since the diameters R2 f the openings 10 and 12 formed at the opposite ends of the insulating tube unit 7 are smaller than the diame-ter R1 of the other portion of the tube 11, the electrode bases 9 having a comparatively small diameter, hence a comparatively small area, can be used for sealing the openings 10 and 12 after inserting the perforated discharge electrodes 8 of a Rogowskii type through the openings 10 and 12 in the insulating tube unit 7, so that the gas-filled discharge tube
The ignition system with a series gap has a discharge tube having a predetermined capacitance and connected in series to a spark plug to prevent the soothing of the spark plug with carbon. Such an ignition system with a series gap disclosed in Japanese Utility Model Laid-open (Kokai) No. 63-lnl486 has a circuit configuration. This known ignition system comprises an ignition coil, a discharge tube, and a spark plug. Each of the discharge tube and the spark plus has a capacitance. The electric potential of the center electrode of the spark plug, i.e., the electric potential of a first predetermined point increases in proportion to the ratio between the respective capacitances of the discharge tube and the spark plug when the voltage V applied across the discharge tube, i.e. the electric potential of another predetermined point, is increased. Discharge occurs in the discharge tube when the electric potential of a first point reaches a sufficiently high level, and then the electric potential of the another predetermined point drops sharply and the electric potential of the first predetermined point increases sharply.
If the circumference of the center electrode of the spark plug is soothed with a carbon layer, it is possible that a leakage current flows through the carbon layer to a portion of the center electrode deep from the extremity. When the center electrode of the spark plug,~3)is in such a soothed condition, the potential of the deep portion of the cen-ter electrode, i.e. the potential of a second predetermined point, increases with the potential of the center electrode with a delay as the potential of the center electrode is increased sharply by the discharge of , .
. ~
' ; . ' ',~ ' .
,; . . :
the discharge tube. Suppose that the firing potential of the center electrode is 8 kV. Then, the firing potential of the deep portion is about 6 kV, because the gap between the deep portion and the casing is smaller than that between the center electrode and the opposite electrode. Consequently, a normal spark discharge is passed between the center elec-trode and the opposite electrode at the point of intersec-tion of a line corresponding to 8 kV and a curve repre-senting the variation of the potential of the center electrode, and an abnormal spark discharge is passed between the deep portion and the casing at the point of intersection of a line corresponding to 6 kV and the curve representing the variation of the potential of the deep portion.
~ However, the normal spark discharge occurs earlier by a - 15 predetermined time between the center electrode and the opposite electrode than the abnormal spark discharge, and hence the spark plug may not be soothed due to the abnormal spark discharge.
The conventional discharge tube comprises a tube formed of an electrically insulating material, such as a ceramic, and having opposite open ends, a pair of electrode bases closely fitted respectively in the opposite ends of the tube, and a pair of discharge electrodes held on the electrode bases within the tube. The tube is filled with an inert gas. The sum of the capacitance between the pair of discharge electrodes and the capacitance between the pair of electrode bases is the capacitance of the discharge tube In such an ignition system, it is desired to employ a compact discharge tube to enable the plug cap attached to the extremity of the high-tension cable to be formed in a compact construction. When the length of the discharge tube of a construction is reduced to increase the capacitance of the discharge tube and such a discharge tube ; ~, ., . ' ': ' , having a comparatively large capacitance is employed in the ignition system and the same spark plug having the same capacitance is used, the potential of the center electrode and the potential of the deep portion of the spark plug increase according to the increase in the capacitance of the discharge tube. Consequently, a time interval between the point of occurrence of the normal spark discharge between the center electrode and the opposite electrode, and the point of occurrence of the abnormal spark discharge becomes very short and hence it is a matter of probability that which of the normal spark discharge and the abnormal spark discharge will occur first. Therefore, increase in the capacitance of the discharge tube entails increase in the possibility of the abnormal spark discharge soothing the spark plug.
Accordingly, it is an object of the present invention to provide a gas-filled discharge tube of a compact construction, having an appropriate capacitance which will not cause soothing the spark plug.
According to the present invention, there is provided a gas-filled discharge tube comprising an insulating tube unit having a tube formed of an electrically insulating material and having openings in the opposite ends thereof, a pair of electrode bases closely attached to the opposite ends of the tube so as to close the openings, respectively, a pair of discharge electrodes attached respectively to opposite inner surfaces of the electrode bases to form a series gap, and an inert gas filling the insulating tube unit, wherein the diameter of peripheries of the openings covered with the electrode bases is smaller than the inside diameter of the tube.
.
.
.
Since the diameter of the portions of the opposite ends of the tube provided with the openings closed by the electrode bases is smaller -.
..
. ?
than that of other portions, the diame~er, hence the area, of the electrode bases may be comparatively small, so that the capacitance between the electrode bases, hence the capacitance of the sas-filled discharge tube, is comparatively small and hence the gas-filled dis-charge tube can be formed in a compact construction without excessively increasing the capacitance.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present invention will become more apparent from the following descrip-tion taken in connection with the accompanying drawings, in which:
Figure 1 is a longitudinal sectional view of a gas-filled dis-charge tube in a first embodiment according to the present invention;
Figure 2 is a longitudinal sectional view of a gas-filled dis-charge tube in a second embodiment according to the present invention;
Figure 3 is a circuit diagram of an ignition system with a series gap;
Figure 4 is a graph showing potential variations at different points in the ignition system of Fig. 3;
Figure 5 is an enlarged fragmentary sectional view of the ex-tremity of a spark plug; and Figure 6 is a longitudinal sectional view of a conventional discharge tube.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
.
'', ; '' Gas-filled discharge tubes embodying the present invention will be described hereinafter with reference to Figs. 1 and 2, in which parts like or corresponding to those of the conventional discharge tube previously described with reference to Figs. 3 to 6 will be denoted by the same reference characters.
First Embodiment Referring to Fig. 1, a gas-filled discharge tube 2 comprises an insulating tube unit 7 formed of an electrically insulating material, such as alumina ceramic, steatite or crystallized glass, and provided with openings 10 and 12 of the same diameter R2 at its opposite ends, a pair of metallic electrode bases 9 attached to the opposite ends of the insulating tube unit 7 so as to close the openings, respectively, a pair of discharge electrodes 8 projecting from the opposite inner surfaces of the electrode bases 9 so as to form a series gap, and an inert gas, such as argon gas or an argon-nitrogen mixed gas, filling the insulating tube unit 7.
The insulating tube unit 7 consists of a tube 11 and an end cap 13 fitted in one end of the tube ll and provided with an opening 12.
The other end of the insulating tube 7 is reduced to form the opening 10 having a diameter R2 smaller than the diameter Rl of the open end of the tube 11 closed by the end cap 13. The tube ll and the end cap 13 are joined together with glass frit 14 or the like to form the insulating tube unit 7 provided with the openings 10 and 12 of the same diameter R2 smaller than the diameter Rl of the open end of the tube 11, i.e., the inside diameter of the tube ll.
, ~
7 z~
The pair of discharge electrodes 8 are inserted through the openings 10 and 12 in the insulating tube unit 7 so as to form a dis-charge gap between the opposite top surfaces thereof. Each of the discharge electrodes 8 is of a so-called Rogowskii type having a flat top surface 8a having a curved periphery 8b, and provided with a number of small holes. Flanges 8c formed around the base ends of -the discharge electrodes 8 are seated on the peripheries of the openings 10 and 12, respectively. The electrode bases 9 have the shape of a cap and are jointed to the peripheries of the openings 10 and 12 so as to hold the flanges 8c of the discharge electrodes 8 on the peripheries of the openings 10 and 12 and to close the openings 10 and 12, respectively.
The openings 10 and 12 may be sealed by soldering the flanges 8c of the discharge electrodes 8 held by the electrode bases 9 to the metallized surfaces 15 of the peripheries of the openings 10 and 12, respectively.
A yas-charging pipe 16 connected to the electrode base 9 is sealed with a sealant after charging the insulating tube unit 7 with the inert gas.
Since the diameters R2 f the openings 10 and 12 formed at the opposite ends of the insulating tube unit 7 are smaller than the diame-ter R1 of the other portion of the tube 11, the electrode bases 9 having a comparatively small diameter, hence a comparatively small area, can be used for sealing the openings 10 and 12 after inserting the perforated discharge electrodes 8 of a Rogowskii type through the openings 10 and 12 in the insulating tube unit 7, so that the gas-filled discharge tube
2 can be formed in a comparatively small length without entailing increase in the capacitance, because the capacitance between the ,,, . ~ ' ~
' electrode bases, hence the capacitance of the gas-filled discharge tube 2, is comparatively small.
The insulating tube unit 7 thus constructed has a comparatively large surface area so that electric discharge passed along the surface of the insulating tube unit, i.e., so-called creeping discharge, can be prevented. An electric discharge can stably be passed between the discharge electrodes 8 of a Rogowskii type at a comparatively high firing potential even if the discharge electrodes 8 are disposed with a small discharge gap.
Second Embodiment Referring to Fig. 2, a gas-filled discharge tube 2 in a second embodiment according to the present invention is substantially the same in construction as the gas-filled discharge tube 2 in the first embodi-ment, except that the gas-filled discharge tube 2 in the second embodi-ment employs an insulating tube unit 7 consists of two short tubes 19.
One end of each of the short tubes 19 is reduced to form an opening 17 of a diameter Rz smaller than the inside diameter R1 of the short tube 19. The edge of the fully open end of one of the short tubes 19 is cut to form an external taper surface 18, and the edge of the fully open end of the other short tube 19 is cut to form an internal taper surface 18;
the taper surfaces 18 are joined closely when the short tubes 19 are joined together with glass frit or the like to construct the insulating tube unit 7.
The effects and advantages of the gas-filled discharge tube 2 in the second emboaiments are the same as those of the gas-filled discharge .
, ~ ~ .
tube 2 in the first embodiment.
If we now refer to the prior art shown in Figures
' electrode bases, hence the capacitance of the gas-filled discharge tube 2, is comparatively small.
The insulating tube unit 7 thus constructed has a comparatively large surface area so that electric discharge passed along the surface of the insulating tube unit, i.e., so-called creeping discharge, can be prevented. An electric discharge can stably be passed between the discharge electrodes 8 of a Rogowskii type at a comparatively high firing potential even if the discharge electrodes 8 are disposed with a small discharge gap.
Second Embodiment Referring to Fig. 2, a gas-filled discharge tube 2 in a second embodiment according to the present invention is substantially the same in construction as the gas-filled discharge tube 2 in the first embodi-ment, except that the gas-filled discharge tube 2 in the second embodi-ment employs an insulating tube unit 7 consists of two short tubes 19.
One end of each of the short tubes 19 is reduced to form an opening 17 of a diameter Rz smaller than the inside diameter R1 of the short tube 19. The edge of the fully open end of one of the short tubes 19 is cut to form an external taper surface 18, and the edge of the fully open end of the other short tube 19 is cut to form an internal taper surface 18;
the taper surfaces 18 are joined closely when the short tubes 19 are joined together with glass frit or the like to construct the insulating tube unit 7.
The effects and advantages of the gas-filled discharge tube 2 in the second emboaiments are the same as those of the gas-filled discharge .
, ~ ~ .
tube 2 in the first embodiment.
If we now refer to the prior art shown in Figures
3 to 6, we see that an ignition system with a series gap has a circuit configuration as shown in Fig. 3. This known ignition system comprises an ignition coil 1, a discharge tube 2, and a spark plug 3. Indicated at C1 and C2 are the respective fixed capacitances of the discharge tube 2 and the spark plug 3. As shown in Fig. 4, the electric potential v1 of the center electrode of the spark plug, i.e., the electric potential of a point B in Fiy. 3, increases in proportion to the ratio between the respective capacitances C1 and C2 of the discharge tube 2 and the spark plug 3 when the voltage V applied across the discharge tube 2, i.e., the electric potential of a point A in Fig. 3, is increased.
lS Discharge occurs in the discharge tube 2 when the electric potential of the point A reaches a sufficiently high level, and then the electric potential of the point A drops sharply and the electric potential of the point B increases sharply.
Fig. 5 shows a portion of the spark plug 3. If the circumference of the center electrode 4 of the spark plug 3 is sooted with a carbon layer 5 as shown in Fig. 5, it is possible that a leakage current flows through the carbon layer 5 to a portion 6 of the center electrode 4 deep from the extremity. When the center electrode 4 of the spark plug 3 is in such a sooted condition, the potential V2 of the deep portion 6 of the center electrode 4, i.e., the potential of a point C in Fig. 3, increases with the potential V1 of the center electrode 4 with a delay as the potential V1 of the center electrode 4 is increased sharply by the discharge of the discharge tube 2. Suppose that the firing potential of the center electrode 4 (point B) is 8 kV. Then, the firi.ng potential of the deep portion 6 (point C) is about 6 kV, because the gap between the deep portion ~., __ . .
9a !
6 and the casing is smaller than that between the center electrode 4 and the opposite electrode. Consequently, as shown in Fig. 4, a normal spark discharge s1 is passed between the center electrode 4 and the opposite electrode at the point of intersection of a line corresponding to 8 kV
and a curve representing the variation of the potential V1, and an abnormal spark discharge S2 is passed between the deep portion 6 and the casing at the point of intersection of a line corresponding to 6 kV and the curve representing the variation of the potential V2. However, as is obvious from Fig. 4, the normal spark discharge S1 occurs earlier by a time t1 between the center electrode 4 and the opposite electrode than the abnormal spark discharge S2, and hence ths ~ spark plug may not be sooted due to the abnormal spark ; l5 discharge S2 .
Fig. 6 shows the discharge tube 2 having the predetermined capacitance C1. The discharge tube 2 comprises a tube 7 formed of an electrically insulating material, such as a ceramic, and having opposite open ends, a pair of electrode bases 9 closely fitted respectively in the opposite ends of the tube 7, and a pair of discharge electrodes 8 held on the electrode bases 9 within the tube 7. The tube 2 is filled with an inert gas. The sum of the capacitance C3 between the pair of discharge electrodes B and the capacitance C4 between the pair of electrode bases 9 is the capacitance C1 of the discharge tube 2.
In such an ignition system, it is desired to employ a compact discharge tube to enable the plug cap attached to the extremity of the high-tension cable to be formed in a compact construction. When the length of the discharge tube 2 of a construction shown in Fig. 6 is reduced to increase the capacitance C1 of the discharge tube 2 and such a discharge tube having a comparatively large ,,, ~
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' ' I , "
9b capacitance is employed in the ignition system and the ~ame spark plug 3 having the same capacitance C2 is used, the potential V1 of the center electrode ~ (point B) and the potential Vz of the deep portion 6 (point C) of the spark plug 3 increase according to the increase in the capacitance of the discharge tube 2 as indicated by broken lines in Fig.
lS Discharge occurs in the discharge tube 2 when the electric potential of the point A reaches a sufficiently high level, and then the electric potential of the point A drops sharply and the electric potential of the point B increases sharply.
Fig. 5 shows a portion of the spark plug 3. If the circumference of the center electrode 4 of the spark plug 3 is sooted with a carbon layer 5 as shown in Fig. 5, it is possible that a leakage current flows through the carbon layer 5 to a portion 6 of the center electrode 4 deep from the extremity. When the center electrode 4 of the spark plug 3 is in such a sooted condition, the potential V2 of the deep portion 6 of the center electrode 4, i.e., the potential of a point C in Fig. 3, increases with the potential V1 of the center electrode 4 with a delay as the potential V1 of the center electrode 4 is increased sharply by the discharge of the discharge tube 2. Suppose that the firing potential of the center electrode 4 (point B) is 8 kV. Then, the firi.ng potential of the deep portion 6 (point C) is about 6 kV, because the gap between the deep portion ~., __ . .
9a !
6 and the casing is smaller than that between the center electrode 4 and the opposite electrode. Consequently, as shown in Fig. 4, a normal spark discharge s1 is passed between the center electrode 4 and the opposite electrode at the point of intersection of a line corresponding to 8 kV
and a curve representing the variation of the potential V1, and an abnormal spark discharge S2 is passed between the deep portion 6 and the casing at the point of intersection of a line corresponding to 6 kV and the curve representing the variation of the potential V2. However, as is obvious from Fig. 4, the normal spark discharge S1 occurs earlier by a time t1 between the center electrode 4 and the opposite electrode than the abnormal spark discharge S2, and hence ths ~ spark plug may not be sooted due to the abnormal spark ; l5 discharge S2 .
Fig. 6 shows the discharge tube 2 having the predetermined capacitance C1. The discharge tube 2 comprises a tube 7 formed of an electrically insulating material, such as a ceramic, and having opposite open ends, a pair of electrode bases 9 closely fitted respectively in the opposite ends of the tube 7, and a pair of discharge electrodes 8 held on the electrode bases 9 within the tube 7. The tube 2 is filled with an inert gas. The sum of the capacitance C3 between the pair of discharge electrodes B and the capacitance C4 between the pair of electrode bases 9 is the capacitance C1 of the discharge tube 2.
In such an ignition system, it is desired to employ a compact discharge tube to enable the plug cap attached to the extremity of the high-tension cable to be formed in a compact construction. When the length of the discharge tube 2 of a construction shown in Fig. 6 is reduced to increase the capacitance C1 of the discharge tube 2 and such a discharge tube having a comparatively large ,,, ~
` ~!
' ' I , "
9b capacitance is employed in the ignition system and the ~ame spark plug 3 having the same capacitance C2 is used, the potential V1 of the center electrode ~ (point B) and the potential Vz of the deep portion 6 (point C) of the spark plug 3 increase according to the increase in the capacitance of the discharge tube 2 as indicated by broken lines in Fig.
4. Consequently, a time interval t2 between the point of occurrence of the normal spark discharge S1 (the point of intersection of the line correpsonding to 8 kV and the curve representing the variation of the potential V1 of the center electrode) between the center electrode 4 and the opposite electrode, and the point of occurrence of the abnormal spark discharge Sz (the point of intersection of the line corresponding to 6 kV and a curve representing the variation of the potential V2 of the deep portion 6) becomes very short and hence it is a matter of probability that which of the normal spark discharge S1 and the abnormal spark discharge S2 will occur first. Therefore, increase in the capacitance C1 of the discharge tube 2 entails increase in the possibility of the abnormal spark discharge S2 sooting th0 spark plug 3.
Although the invention has been described in its preferred forms with a certain degree of particularity, obviously many changes and variations are possible therein.
It is therefore to be understood that the present invention may be practiced otherwise than as specifically described herein without departing from the scope and spirit thereof.
:, ~
' ~,
Although the invention has been described in its preferred forms with a certain degree of particularity, obviously many changes and variations are possible therein.
It is therefore to be understood that the present invention may be practiced otherwise than as specifically described herein without departing from the scope and spirit thereof.
:, ~
' ~,
Claims (3)
1. A gas-filled discharge tube comprising:
an insulating tube unit having a tube formed of an electrically insulating material and having openings in opposite ends thereof;
a pair of electrode bases closely attached to the opposite ends of the tube unit so as to seal the openings, respectively;
a pair of discharge electrodes attached respectively to opposite inner surfaces of the electrode bases to form a series gap; and an inert gas filling the insulating tube unit;
characterized in that the diameter of peripheries of the openings covered with the electrode bases is smaller than the inside diameter of the tube.
an insulating tube unit having a tube formed of an electrically insulating material and having openings in opposite ends thereof;
a pair of electrode bases closely attached to the opposite ends of the tube unit so as to seal the openings, respectively;
a pair of discharge electrodes attached respectively to opposite inner surfaces of the electrode bases to form a series gap; and an inert gas filling the insulating tube unit;
characterized in that the diameter of peripheries of the openings covered with the electrode bases is smaller than the inside diameter of the tube.
2. A gas-filled discharge tube according to Claim 1, wherein the tube of the insulating tube unit consists of two shorter tubes, one end of each of the shorter tubes is reduced to form the opening.
3. A gas-filled discharge tube according to Claim 1 or 2, wherein the discharge electrodes are perforated discharge electrodes of a Rogowskii type.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1989082242U JPH0322388U (en) | 1989-07-14 | 1989-07-14 | |
| JP1-82242 | 1989-07-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2019909A1 true CA2019909A1 (en) | 1991-01-14 |
Family
ID=13768949
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002019909A Abandoned CA2019909A1 (en) | 1989-07-14 | 1990-06-27 | Gas-filled discharge tube |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0407837A3 (en) |
| JP (1) | JPH0322388U (en) |
| CA (1) | CA2019909A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10203649A1 (en) * | 2002-01-30 | 2003-08-14 | Karlsruhe Forschzent | Switching spark gap |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH537521A (en) * | 1970-11-16 | 1973-05-31 | Bosch Gmbh Robert | Coil ignition system for the operation of internal combustion engines with at least one pre-spark gap switched on on its high voltage side |
| NL7415840A (en) * | 1974-12-05 | 1976-06-09 | Philips Nv | High pressure discharge tube for lamp with narrow ends - has mould with flexible polyurethane outer jacket and polycrystalline wall structure |
| DE3035730A1 (en) * | 1980-09-22 | 1982-05-13 | Kraftwerk Union AG, 4330 Mülheim | TEA TYPE HIGH-ENERGY LASER WITH LASER AXIS PARALLEL PRE-IONIZING RODS |
| DE3523299A1 (en) * | 1985-06-28 | 1987-01-08 | Beru Werk Ruprecht Gmbh Co A | Auxiliary spark gap |
| JPS62262384A (en) * | 1986-05-08 | 1987-11-14 | 株式会社 サンコ−シヤ | Arrestor |
| EP0361357B1 (en) * | 1988-09-27 | 1996-12-18 | Yazaki Corporation | Discharge lamp |
| JPH0638358B2 (en) * | 1988-09-28 | 1994-05-18 | ウエスト電気株式会社 | Gas filling method for constant voltage discharge tube for ignition device of internal combustion engine |
| JPH0355786A (en) * | 1989-04-14 | 1991-03-11 | West Electric Co Ltd | Constant voltage discharge tube for igniter |
-
1989
- 1989-07-14 JP JP1989082242U patent/JPH0322388U/ja active Pending
-
1990
- 1990-06-27 CA CA002019909A patent/CA2019909A1/en not_active Abandoned
- 1990-06-29 EP EP19900112498 patent/EP0407837A3/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| EP0407837A3 (en) | 1991-08-07 |
| EP0407837A2 (en) | 1991-01-16 |
| JPH0322388U (en) | 1991-03-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |