JPH01313873A - Voltage regulator tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a constant voltage discharge tube used in series connection with a spark plug in an ignition system for an internal combustion engine.

BACKGROUND OF THE INVENTION It is known that contamination of spark plugs has a very large effect on the lifespan of ignition systems for internal combustion engines that have been commonly used in the past.

Fouling of a spark plug is caused by conductive substances such as carbon, water, or lead compounds adhering to the surface of the insulating porcelain body of the spark plug.
Spark current leaks through this conductive material and causes the spark to fly sideways, preventing sparks from flying normally between the electrodes. Depending on the type of conductive material mentioned above, it is broadly classified into smoldering contamination and lead contamination. .

On the other hand, in order to eliminate the negative effects of contamination as described above, a series spark gap discharge tube is installed between the ignition plug and the ignition coil, and the voltage applied to the ignition plug is suddenly increased to remove the energy required for ignition from contamination. For example, Japanese Patent Application Laid-Open No. 47-1980 suggests that the leakage current can be supplied to the spark plug before it subsides.
It has been proposed and disclosed in Publication No. 10556 and the like.

The above document describes that 8 kV in a high voltage conductor connected with a certain series spark spacing in terms of gas-filled closed discharge space.
The free end of the series spark gap responds with a fixed ignition voltage value between
+a apart from each other, made of materials that do not scatter at least within the range of spark flashover, and 1 to 1
An ignition coil device for operating an internal combustion engine is proposed, characterized in that it is surrounded by a gas that does not react with the above-mentioned materials at a pressure of 0 atmospheres, more preferably 2 to 5 atmospheres.

and the gas is nitrogen with a purity of at least 98% or argon with a purity of at least 99%;
Further, the free end, that is, the electrode contains 90% by weight or more of aluminum, cerium, hafnium, lanthanum, niobium, tantalum, or titanium.

Consisting of vanadium or zirconium nitrides, or a mixture of these metal nitrides, two of the compounds
It is also disclosed that it contains an oxide or oxynitride corresponding to an oxygen content of 58% or less.

Problems to be Solved by the Invention The above proposal having the above-mentioned configuration is such that even if the spark plug is contaminated, the time from voltage application to dielectric breakdown between the electrodes of the spark plug and sparks flying is short. The effect of not being significantly affected by leakage current can be expected.

However, considering the following points, there is still a problem that the spark plug may not be able to perform proper ignition operation, and an improvement is desired when considering its practical use.

In other words, the ignition voltage of the spark plug responds to the supplied average voltage value of 8 to 30 kV as described in the previous proposal, and it is better to reduce it to avoid noise generation or miniaturization of the ignition device. It is well known that it is preferable in terms of
On the other hand, in recent years, taking into consideration the tendency for the compression ratio to increase with the aim of improving fuel efficiency, the voltage is usually set at about 10 to 25 kV.

However, in order to reliably prevent the internal combustion engine from smoldering, the supply voltage must be set to a certain high value even when the voltage is supplied to the spark plug steeply across the series spark interval. This has been confirmed through experiments; for example, in one internal combustion engine, the steep voltage supplied to the spark plug that could reliably prevent smoldering due to contamination was 18 kV or more.

That is, when a voltage of 18 kV or less is supplied, a problem arises in that the internal combustion engine smolders and the rotational speed during idling becomes extremely unstable.

In addition, even if the atmosphere mixes in the closed discharge space where the series spark interval is provided, the series spark interval length is set to approximately 12 m or less in order to ensure discharge at a voltage of 25 kV or less that can be supplied by the ignition coil. This has been confirmed from experimental results that take into account the extremely large variation in discharge voltage in the atmosphere shown in FIG.

Now, if we look at the proposal mentioned above, the electrode spacing is set at 1 to 5 mm, more preferably 1.5 to 3 W11, but at such a discharge length, for example, the 18 k
Setting the discharge starting voltage at a high voltage of V is possible by using nitrogen or argon as a filler gas as disclosed in the above proposal.
It becomes extremely difficult to use it under an enclosed pressure condition of ~10 atm, more preferably 2 to 5 atm.

In other words, the proposed device described above has a short discharge length between sparks, the gas pressure is not very high, and the discharge starting voltage is 18k.
It cannot be easily set to a high voltage of V or higher, and there is a risk that proper ignition operation may not be possible depending on the state of contamination.

It is also possible to set the above-mentioned discharge length to 5I1w11 or more, but in this case, the influence of the grounding body existing on the outer periphery of the series spark interval begins to appear.

In other words, the above-mentioned spark interval is generally provided just above the spark plug to prevent energy loss, and in this case, the internal combustion engine body serves as a grounding body, and the conductance between this body and the tip of the main electrode, that is, the discharge part. As shown in Fig. 5, the conductance C becomes electrically equivalent to the spark interval and the state in which the spark plug is connected in parallel with the series body, and the discharge starting voltage increases, contrary to the aim. There is a risk that it will decrease.

Therefore, in the proposed device described above, it was not possible to unnecessarily lengthen the discharge length.

Further, in the above-mentioned proposal, the discharge length is limited to 5 lengths or less also from the viewpoint of the after-discharge voltage.

In other words, it is preferable that the after-discharge voltage, so-called discharge sustaining voltage, is lower because it can reduce the amount of energy on the input side, and in the previous proposal, it is set to 1/4 or less of the ignition voltage, more preferably 1/10 or less. The electrode spacing is 1 to 5 meters,
More preferably, it is set to 1.5 to 3 mm.

However, according to the applicant's experiments, although the length or shortness of the discharge length certainly contributes to the high or low discharge sustaining voltage, the type and pressure of the gas sealed in the discharge space have a greater influence. It has been confirmed that it has.

That is, to put it simply, the discharge sustaining voltage is much lower when argon is filled than when nitrogen is filled.

Therefore, in the previous proposal, if only the discharge sustaining voltage is considered, it is sufficient to use argon, but in this case, the discharge starting voltage also decreases, and as mentioned in that document, for example, if the discharge starting voltage is 12 kV or less, It is only applicable to the case of discharge starting voltage, and the proposed device as it is cannot set a discharge starting voltage of 18 kV or more as mentioned above, and has the disadvantage that problems caused by contamination cannot be reliably prevented. It turns out.

The present invention has been made in consideration of the above-mentioned points, and provides a constant voltage discharge tube for an ignition device of an internal combustion engine, which has a high discharge starting voltage of 18 kV or more and has an extremely low discharge sustaining voltage. The purpose is to

Means for Solving the Problems The constant voltage discharge tube of the present invention is a discharge tube equipped with a pair of main electrodes hermetically sealed at both ends of a cylindrical envelope, and the main electrode spacing G is set at 5 to 12 m. Then, xenon gas with a purity of 99% or more is sealed in a cylindrical envelope at a gas pressure of 6.5 to 20 atmospheres, and the distance between the main electrodes G and the discharge part of the main electrode and the inner wall surface of the outer envelope is determined. The relationship with the shortest distance is 0.2×G≦D,
Furthermore, the main electrode spacing G and gas pressure are adjusted to 5 to 12 mm as described above so that the discharge starting voltage is within the range of 18 to 25 kV.
Alternatively, the pressure is within the range of 6.5 to 20 atmospheres.

Operation The constant voltage discharge tube according to the present invention has a condition that the distance between the discharge part of the main electrode and the inner wall of the envelope is at least 0.2 times the main electrode spacing G, so that the discharge part of the main electrode and the earth body are connected to each other. The distance between the internal combustion engine and the main body is large (this means that it can be set).

Therefore, even when the interval between the main electrodes is increased, the influence of the conductance due to the grounding body can be prevented, and the discharge starting voltage can be prevented from decreasing.

That is, in the constant voltage discharge tube according to the present invention, the distance between the main electrodes is set to a length of 5IIlII+ or more, and as a result of this length, a high discharge starting voltage can be achieved as intended.

In addition, although xenon gas, which has a low discharge starting voltage and discharge sustaining voltage, is used as the filling gas, the filling pressure is set high, so the discharge starting voltage is The pressure will be increased.

Embodiment FIG. 1 is a sectional view showing an embodiment of a constant voltage discharge tube for an internal combustion engine according to the present invention.

As is clear from the figure, this embodiment includes a cylindrical envelope 1 made of an insulator such as ceramic, and a first main electrode 2 connected to an ignition coil (not shown) of an ignition device at both ends; A second main electrode 3 connected to a spark plug (not shown) is hermetically sealed by a well-known heat sealing process using an adhesive member 4.

The first main electrode 2 is formed of a metal conductor cap 5 and a sintered metal electrode 6 containing an emission agent welded to this cap 5, and the second main electrode 3 is formed of a metal conductor cap 7 and a sintered metal electrode 6 that is welded to this cap 5. It is formed with a rod-shaped electrode 8 to be welded.

The sintered metal electrode 6 is made of a main metal such as a high-melting point metal such as tungsten, tantalum, or molybdenum, a reducing agent such as nickel, titanium, vanadium, or zirconium, and cesium.

It is composed of emission agents such as aluminum, barium, and strontium. On the other hand, the rod-shaped electrode 8 is made of a pure metal with a high melting point such as tungsten, tantalum, or molybdenum, or an oxide or nitride thereof.

A cylindrical envelope 1 and a first main electrode 2. The closed space 9 formed by the second main electrode 3 is filled with xenon gas having a purity of 99% or more at a pressure of, for example, 10 atmospheres based on the experimental results described later.

Further, the dimensions of each part in the illustrated example are based on the experimental results described later, and the cylindrical envelope 1 has an outer diameter of 16 m+a and an inner diameter of 8 mm.

The tip of the sintered metal electrode 6, that is, the discharge part has an outer diameter of 2
m, the outer diameter of the rod-shaped electrode 8 is 1 min, and the distance between the two electrodes is G.
That is, the discharge length G is set to 10 ww.

That is, it is clear that the relationship between the discharge length G and the shortest distance between the discharge part of the electrode and the inner wall surface of the cylindrical envelope 1 satisfies the condition 0.2×G≦D.

Furthermore, the metal conductor caps 5 and 7 and the adhesive member 4 are appropriately selected so that their thermal expansion coefficients are equal or approximately equal to that of the cylindrical envelope 1.

Needless to say, it is also used. In addition, as is clear from FIG. 1, the metal conductor caps 5 and 7 have protrusions 5a on their peripheries that are positioned in grooves 1a provided on the end face of the cylindrical envelope 1 via adhesive members 4; 7a,
Therefore, the range of action of the adhesive member 4 between the cylindrical envelope 1 and the metal conductor caps 5, 7 is extremely wide, and this embodiment can form a strong sealed portion of the metal conductor caps 5, 7.

Now, in one embodiment of the constant voltage discharge tube according to the present invention having the above-described structure, when examining the discharge amount, starting voltage, and discharge sustaining voltage, it is found that they are 20 kV and 0.2 kV, respectively.
The value was 5kV.

In other words, the discharge starting voltage is the above-mentioned value of 18 kV or more, and the discharge sustaining voltage is extremely reduced to 1/80 of that value, making it possible to prevent the internal combustion engine from smoldering due to fouling of the spark plug with a small amount of energy. It has been confirmed that extremely favorable characteristics can be obtained.

On the other hand, it goes without saying that the above-mentioned discharge starting voltage and the like are influenced by the dimensions of each part such as the discharge length in the illustrated embodiment, or the pressure of the filled gas (this point will be described in detail below).

First, the relationship between the discharge length G and the shortest distance between the electrode discharge section and the inner wall surface of the cylindrical envelope 1 will be described.

In order to confirm the above relationship, the applicant created discharge tubes in which the relationship between the discharge length G and the distance was varied in various ways. An experiment was conducted to examine the discharge starting voltage when the battery was placed close to the main body, that is, when the discharge was caused in the presence of a grounding body, and to investigate the ratio.

FIG. 2 is a characteristic diagram showing the experimental results, and as is clear from this diagram, when the relationship between the discharge length G and the distance, that is, D/G becomes 0.2 or more, the ground It was confirmed that the effect of In addition,
Even if the above D/G is the same, some variation in characteristics will occur depending on the value of the discharge length G, for example, but most of these variations occur in the region where the above D/G is 0.2 or less, There are no particular problems with the above confirmation details.

That is, even if the discharge length G is set long, the above D/G is 0.
If the distance is set to be 2 or more, it can be expected that the discharge starting voltage will be increased by increasing the discharge length G, regardless of the presence or absence of a grounding body.

Next, the relationship between the discharge starting voltage or discharge sustaining voltage, the filled gas pressure, and the discharge length G will be described.

In order to ensure the above relationship, the applicant has various discharge lengths in which the relationship D/G between the discharge length G and the distance 1ll1D is 0.2 or more and 12+m or less, and xenon gas is Various pressure-sealed discharge tubes having the structure shown in FIG. 1 were made, and experiments were conducted to investigate the discharge starting voltage and discharge sustaining voltage of each discharge tube.

Figure 3 (a) and (b) are characteristic diagrams showing the experimental results. As is clear from Figures (a) and (b), both the discharge starting voltage and the discharge sustaining voltage have a long discharge length. It was also confirmed that the higher the sealed gas pressure, the higher the voltage. Regarding the discharge sustaining voltage, we investigated the characteristics for various input voltage values, but there was almost no difference when discharging, and Figure 3 (b) shows the characteristics when a high voltage of 35 kV is input. ing.

Now, let's first look at the relationship between the discharge starting voltage, discharge length, and sealed gas pressure.

Regarding the discharge starting voltage, as mentioned earlier, in order to reliably prevent the negative effects caused by fouling of the spark plug, it is necessary to set the discharge starting voltage to 18k.
Considering that a high voltage of V or more must be rapidly supplied to the spark plug, and the ignition voltage of the spark plug is usually set to 10 to 25 kV, it is preferable to set it in the range of 18 to 25 kV. Needless to explain in detail, the applicant of the present application has also conducted further studies within the above range.

In other words, if we look in more detail at the relationship between the discharge length and the filled gas pressure within the above voltage range, we find that in the region where the discharge length is short, the filled gas pressure is extremely high, and therefore it is difficult to manufacture discharge tubes in such a region. It is possible that it will become.

In other words, in the embodiment of the constant voltage discharge tube according to the present invention shown in FIG. 1, the envelope 1 and the electrodes 2 and 3 are hermetically sealed by heating using the adhesive member 4. Although it depends on the heating temperature, it goes without saying in detail that the higher the pressure of the sealed gas, the more difficult the gas filling work and the heat sealing work described above, considering the thermal expansion of the sealed gas and the mechanical strength of the sealed part. do not have.

Therefore, the discharge length cannot be unnecessarily set to a short value as disclosed in the proposed device mentioned at the beginning, and according to the applicant's study, the current limit for increasing the filled gas pressure is about 20 atm. Therefore, when setting the discharge starting voltage in the voltage range mentioned above from this point, the discharge length is 5 mm.
It was confirmed that the above settings were necessary.

On the other hand, as is clear from Figure 3(b), the discharge sustaining voltage varies slightly depending on the discharge length and the filled gas pressure, but under the conditions of 12 mm or less and 20 atmospheres or less as described above, 0. The voltage was 6 kV or less, and it was confirmed that the discharge tube having the structure shown in FIG. 1 and filled with xenon gas had extremely favorable characteristics.

In addition, when considering the mass production of discharge tubes or the miniaturization of ignition devices, it is better to keep the filled gas pressure low (and also the input voltage required for discharge to be low), so the discharge length is more preferably 8 to 8. 10m+ and discharge starting voltage is 20kV±2kV
It should be set to a certain degree. This is because, considering only the decrease in the pressure of the filled gas, by setting the discharge length to 12 mm, the
Although a discharge starting voltage of 18kV can be obtained at atmospheric pressure, the ignition device is larger than when the discharge length is set to 12+ma or less.

From this point of view, the discharge length and discharge starting voltage range as described above are particularly practical ranges when considering mass productivity and device shape.

Effects of the Invention The constant voltage discharge tube according to the present invention has a discharge starting voltage of 18 to 2
In order to obtain a high voltage of 5 kV, the discharge length was set in the range of 5 to 12 mm, and the pressure of the xenon gas sealed in the discharge space was adjusted to 6 mm.
．． It is set to a value within the range of 5 to 20 atmospheres, and the shortest distance between the main electrode discharge part and the inner wall of the envelope is at least 0.2 times the discharge length, making it suitable for use as a spark plug for internal combustion engines. By using them in series, it is possible to expect the effect of reliably preventing smoldering due to contamination of the spark plug.

・In addition, since xenon gas with a purity of 99% or more is used as the filler gas, the discharge sustaining voltage can be controlled to a low value. You can also expect good results.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a constant voltage discharge tube according to the present invention, and FIG. 2 shows the relationship between the discharge length G and the shortest distance between the main electrode discharge part and the inner wall surface of the envelope. Characteristic diagram showing the ratio of discharge starting voltage when it exists and when it does not exist, 3rd
Figures (a) and (b) are characteristic diagrams showing the relationship between discharge starting voltage and xenon gas filling pressure and the relationship between discharge sustaining voltage and xenon gas filling pressure at various discharge lengths, respectively.
FIG. 4 is a characteristic diagram showing the relationship between discharge starting voltage and discharge length in the atmosphere, and FIG. 5 is an equivalent circuit diagram for explaining the influence of the internal combustion engine main body as a grounding body. DESCRIPTION OF SYMBOLS 1... Cylindrical envelope, 2... First main electrode, 3... Second main electrode, 4... Adhesive member, 5.7. ...Metal conductor cap, 6...
・Sintered metal electrode, 8... Rod-shaped electrode, 9...
...closed space. Name of agent: Patent attorney Toshio Nakao and 1 other person t・-F1
GL outer eye each 2-...Sai ft * 2nd figure 3rd figure stroke input ° space pressure r atmospheric pressure] (b) Seasonal pressure

[翫ε]

Figure 4 Figure 5 7-Also%

Claims (1)

[Claims] A cylindrical envelope made of an insulator such as ceramic is provided with a pair of main electrodes at both ends, and the main electrode interval G is 5 to 12 m.
m, and xenon gas with a purity of 99% or more is sealed in the cylindrical envelope at a gas pressure of 6.5 to 20 atmospheres, and the distance between the main electrodes G, the discharge part of the main electrodes, and the outside of the cylinder is The relationship between the shortest distance D to the inner wall surface of the enclosure is 0.2×G≦D, and the main electrode spacing G and the filled gas pressure are set as above so that the discharge starting voltage is within the range of 18 to 25 kV. 5～
A constant voltage discharge tube of 12 mm or within the range of 6.5 to 20 atmospheres.