DE3028359A1 - SPARK PLUG WITH OXYGEN PROBE - Google Patents

Description

NISSAN MOTOR CO., LTD. TER MEER ■ MÜLLER · STEINMEISTER Case: GO89-80

3028353

DESCRIPTION

The invention relates to a spark plug for internal combustion engines, and more particularly to a spark plug having one of a center electrode surrounded by an insulator and a side electrode forming a spark gap with the center electrode .

Generally, spark plugs consist of a center electrode surrounded by an insulator and one at one end Opposite side electrode, with which it defines a spark gap or a spark gap, so that then, when there is a high electrical voltage generated by an ignition coil between the center electrode and the side electrode is applied, in the spark gap a safer and more intense spark is generated, with the result that the compacted Air / fuel mixture explodes in the combustion chamber of the internal combustion engine.

Such spark plugs are used in the internal combustion engines of conventional automobiles, racing vehicles, powered aircraft, agricultural machines, ships, generators or the like. Furthermore are a variety of Spark plugs have been proposed in which the heat values or the degree of thermal radiation of the spark plugs vary and with which the generation of noise is prevented.

Recently it is with the development of internal combustion engines It has become necessary for automobiles to purify the exhaust gas by improving the combustion efficiency and save energy. For this purpose it has already been proposed to take the exhaust gases from the internal combustion engine

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N.TSSAN MOTOR CO., LTD. TER MEER -MÜLLER · SY ^ IN.vlEISTER Case: GO89-8 0

Using a 3-way catalytic converter too clean in which converter the components carbon monoxide and Hydrocarbon is oxidized and nitrogen oxide is reduced and are converted into the harmless products carbon dioxide, water vapor and nitrogen gas. The catalytic 3-way converter works best when supplied with exhaust gases created by burning an air-fuel mixture with a stoichiometric air / fuel ratio (where the weight ratio of air to fuel in the case of the combustion of gasoline is approximately 14.7: 1). One continues to run Combustion is most effective and thus contributes to energy savings. As a result, an attempt was made to incinerate the air-fuel mixture is always at a stoichiometric one Effecting the air / fuel ratio using an oxygen concentration cell type oxygen probe, with the air / fuel ratio of the mixture fed to the combustion chambers which concentration is controlled as a function of the change in the oxygen concentration in the exhaust gases because of increasing air content it becomes larger when the air / fuel ratio is above the stoichiometric Value increases.

There are already various constructions of oxygen probes of the oxygen concentration cell type has been proposed, for example that in the form of a tube made of an oxygen ion closed at one end conductive solid electrolyte, which is provided with electrodes on its inner and outer surface, such as it is described in, for example, Japanese Patent Laid-Open No. 49-130292, and the probe formed by

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TER MEER · MÜLLER ■ STEINMEISTER

NISSAN MCGXDR CO., LTD. Case: GO89-80

a solid electrolyte and electrodes are placed on top of one another in the form of thin layers, as described in US Pat 3,578,578 and Japanese Patent Laid-Open No. 5 2-136689.

With conventional methods of determining the oxygen concentration in the exhaust gases it is common practice to place the oxygen probe in an exhaust pipe, As a result, it takes a considerable amount of time from the combustion of the air-fuel mixture to its determination of the air / fuel ratio passes, so that the feedback control of the air / fuel ratio is delayed. Accordingly, the conventional measuring devices for determining the air / fuel ratio have apart from the disadvantages mentioned above, the following problems: The oxygen probe is placed in an exhaust pipe, to which the exhaust gases of all cylinders of the internal combustion engine are fed, which are in a multi-cylinder Drischen internal combustion engine are generated. It should be noted that with multi-cylinder internal combustion engines the burns in the cylinders proceed differently, so that it improves the combustion efficiency is not suitable, the air / fuel ratio of all cylinders of the internal combustion engine uniformly depending on an averaged oxygen concentration in the mixed Control exhaust gases from all cylinders of the internal combustion engine.

It would therefore make sense to place the oxygen probe in the combustion chamber of each cylinder in a suitable manner to arrange the internal combustion engine. The ver

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NISSAN MOTOR CO., LTD. TER MEER ■ MÜLLER · STEINMEISTER Case: GO8 9-80

The combustion chamber of the internal combustion engine must, however, have a small volume and only have a few components be equipped to improve the combustion efficiency in the combustion chamber. Hence is it is difficult to place the oxygen probe in the combustion chamber. Furthermore, in the combustion chamber, in which the suction, compression and explosion of the fuel take place, very strict conditions, among which none of the oxygen probes known to date and used in practice are more satisfactory VJeise would work.

Accordingly, the object of the present invention is to solve the above problems and an apparatus for determining or measuring the oxygen concentration to create in the combustion chamber or the combustion chamber of an internal combustion engine.

This object is now achieved by the characterizing features of the spark plug according to the invention according to the main claim.

The subclaims relate to particularly preferred embodiments this subject of the invention.

According to the invention, an oxygen probe or an oxygen is used probe element arranged on or on or in the insulator of a spark plug, the one surrounded by the insulator Having a center electrode and a side electrode. The oxygen probe provided in this way measures the oxygen concentration in the combustion chamber of a combustion

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engine and in this way the air / fuel ratio prevailing in the combustion chamber. At this Arrangement will make it possible to adjust the air / fuel ratio of each cylinder of the internal combustion engine to control, so that a much more precise control of the Air / fuel ratio becomes possible compared to the conventional arrangement in which the control of the air / fuel ratio as a function of the oxygen concentration in an exhaust pipe in which the exhaust gases of all cylinders of the internal combustion engine are combined, takes place. Since according to the invention the Determination of the air / fuel ratio takes place immediately after the combustion of the air / fuel mixture, can provide feedback control of the air / fuel ratio instantly causing the feedback control response to be substantial is improved. Furthermore, there is an improved resistance of the oxygen probe under the severe operating conditions, as it is part of the spark plug that is resistant under these conditions is what arrangement according to the invention also solves the space problems that would otherwise arise during installation an oxygen probe in the combustion chamber.

The invention will be explained in more detail below with reference to the accompanying drawings. In the drawings, in which the same reference numerals for corresponding Parts and elements stand, show:

Fig. 1 is a longitudinal section through an embodiment of the spark plug according to the invention with oxygen probe;

FIG. 2 is a view of that shown in FIG

Spark plug viewed lengthways from one of its ends;

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NXSSAN MOTOR CO., LTD. TER MEER - MÜLLER STEINMEISTER Case: GO89-80

3 is an enlarged sectional view showing an example of the oxygen probe shown in FIG. 1 reproduces;

FIG. 4 is a further enlarged sectional view of the oxygen probe shown in FIG. 2;

Figures 5 and 6 are graphical curves showing the relationship between the air / fuel ratio and the output voltage the oxygen probe reproduce;

Fig. 7 is an enlarged sectional view of the further example of the oxygen probe;

Fig. 8 is an enlarged sectional view of another example of the oxygen probe;

9 is an enlarged sectional view of another example of the oxygen probe;

Fig. 10 is a graph ₍ showing the relationship between the air-fuel ratio and the electrical resistance of an oxide semiconductor;

Figures 11A-11B including schematic representations showing clarify the process for manufacturing the oxygen probe, and

Fig. 12 is a graph showing the output voltage characteristic of that oxygen probe; those illustrated in FIGS. 11A to 11B Process has been established and experimentally investigated.

1-4 is an embodiment of one according to the invention Spark plug with oxygen probe 8 shown. The spark plug is provided with a center electrode 1, which is from is surrounded by an insulator 2, with an intermediate filling powder 3 between the center electrode 1 and the insulator 2

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is arranged. A metal body 4 is fixedly arranged on the outer circumference of the insulator 2, between which metal body 4 and the insulator 2 an intermediate filler powder 5 is arranged. The metal body 4 comprises a screw head section 4a and a section 4b with an external thread and furthermore has an integrally formed side electrode Ac , which is removed from the end of the center electrode 1 via a spark gap 6. The other end of the center electrode 1 is firmly connected to a connection terminal 7 which ensures electrical contact. The insulator 2 has a corrugated portion 2a.

The oxygen probe or the oxygen probe element 8, which has a multilayer film structure is at one end of the insulator 2 near the spark gap 6 arranged. The insulator 2 has a through hole 2b through which a line is passed, which receives the electromotive force generated by the oxygen probe 8. The oxygen probe 8 is fixedly arranged on a plate-shaped substrate 10, the structural strength as a supporting element the oxygen probe ensures. The oxygen probe comprises a comparison electrode 11 applied to the plate-shaped substrate 10. On the comparison electrode 11, an oxygen ion conductive is more solid Electrolyte 12 applied, on which solid electrolyte the measuring electrode 13 is applied. A porous protective layer 14 covers the solid electrolyte 12 and the Measuring electrode 13. The electrodes 11 and 13 are electrical Via line 9 to a direct current source 15 and a voltage measuring device or voltmeter 16 tied together. As shown in Fig. 4, the

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KILSAN MOTOR CO., LTD. TER SEA - MÜLLER · S [L-INMEISTLh! Case: GO89-80

oxygen arranged on the plate-shaped substrate 10 probe 8 securely arranged in a cavity 2c formed at the end of the insulator 2 of the spark plug is.

With this arrangement, if the two electrodes 11 and 13 are made of a catalytically active material, such as platinum, and the positive and negative connections of the direct current source 15 are connected to the comparison electrode 11 and the measuring electrode 13, a movement of oxygen ions in the solid electrolyte 12 in the direction from the measuring electrode 13 to the Comparison electrode 11. This increases the oxygen partial pressure at the comparison electrode 11. If the rise in partial pressure of oxygen becomes excessively high, Oxygen flows out through the porous solid electrolyte, so that the oxygen partial pressure is at a high value

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from about 10 to 10 atm. On the surface of the measuring electrode 13 is due to the fact that the measuring electrode is formed from a catalytically active material, the oxidation promoted, which leads to As a result, the oxygen partial pressure changes abruptly at the stoichiometric air / fuel ratio. As a result, the output voltage characteristic of the oxygen probe 8 changes at the stoichiometric one Air / fuel ratio as shown in FIG. 5 is.

As a result of this, the oxygen probe attached to the spark plug generates during the intake stroke and the compression stroke the internal combustion engine never has an output voltage, those only on the side of the rich (low) air / fuel ratio or in the rich range

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TER MEER · MÜLLER · STEINMEISIER

NISSAN MOTOR CO., LTD. Case: GO89-8 0

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is generated as a result of the abrupt decrease in the partial pressure of oxygen after burning the air-fuel mixture. When the oxygen probe 8 thus has no output voltage after the combustion of the air-fuel mixture generated, it is concluded that the air / fuel ratio on the lean (high) side of the air / fuel ratio is found so that the air / fuel mixture is controlled so that it is toward the rich side is shifted to achieve combustion at a stoichiometric air / fuel ratio. If the Oxygen probe 8 on the other hand generates an output voltage, it can be concluded that the air / fuel ratio is on the rich side, so that the air / fuel ratio is shifted to the lean side in order to turn the combustion at a stoichiometric one Achieve air / fuel ratio. this has As a result, the 3-way catalytic converter works most efficiently.

The oxygen partial pressure at the comparison electrode 11 can cannot be maintained at a stable value if no DC power source 15 is used. Even with the output voltage characteristic, which one obtains with such an arrangement, however, it is possible to adjust the air / fuel ratio to keep at the stoichiometric value. For example, when the partial pressure of oxygen at the comparison electrode 11 and the air / fuel ratio are low of the exhaust gas is in the lean range, as a result of the high oxygen partial pressure at the measuring electrode 13 generates an output voltage. The generation of the Output voltage is then interrupted when the exhaust gas reaches the comparison electrode 11 with a high oxygen partial pressure via the porous solid electrolyte 12. In the-

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In this state the oxygen partial pressure is at of the comparison electrode 11 at a high value. If then the exhaust gas in its composition in is in the rich range, an output voltage is generated, whose polarity is reversed compared to the above case. Thus, the output voltage is instantaneously in Form of a pulsating voltage generated only during the period of time that is necessary for the exhaust gases the different oxygen partial pressures onv / iron over the porous, solid electrolyte 12 the Have reached reference electrode 11.

If the measuring electrode 13 or the comparison electrode is made of a catalytically inert material, such as silicon carbide (SiC), or a catalytically active material such as platinum (Pt) are formed and furthermore the positive or negative Connections of the direct current source 15 to the comparison electrode 11 and the measuring electrode 13, respectively are, the movement of the oxygen ions in the solid electrolyte 12 in the direction of the measuring electrode 13 becomes the comparison electrode 11 on the release of oxygen balanced by the porous, solid electrolyte 12, so that the oxygen partial pressure at the

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same electrode 11 to a value of 10 to 10 atm is held. Since the measuring electrode 13 from the catalytically inert material, the output voltage will be generated in the rich portion of the air / fuel ratio and gradually decreases as the air / fuel ratio moves to the lean side of the, Air / fuel ratio changed, causing the Oxygen partial pressure in the exhaust gas increases, as shown in FIG. 6. So if those with the Oxygen probe 8 equipped spark plug is used,

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N ■: SSAN MOTOR Co. , LTD. TER MEER MÖLLER STE.INMEISTER Case: GO89-8 0

it becomes possible to control the combustion to operate at a weakly lean air / fuel ratio expires, in which a better fuel economy can be achieved.

Fig. 7 illustrates a further embodiment of the provided with the oxygen probe 8 according to the invention Spark plug.

In this case, the oxygen probe 8 is firmly on the plate-shaped substrate 10 arranged, which serves as a supporting element and the structural strength of the Oxygen probe 8 ensures. On the plate-shaped Substrate 10 are successively a material 17 which constitutes part of the element with which a comparison oxygen fpartialdruck is generated, the comparison electrode 11, the solid electrolyte 12, the measuring electrode 13 and the porous Protective layer 14 arranged. In this case, the oxygen partial pressure of the comparison electrode 11 is determined with the aid of the material 17 generating the comparison oxygen partial pressure is kept at a constant value, so that it is not necessary to use the DC power source 15. The oxygen probe 8 can be constructed in the manner be that on the plate-shaped substrate 10 successively the comparison electrode 11, the material 17 for Generation of the comparison oxygen partial pressure, the solid electrolyte 12, the measuring electrode 13 and the porous protective layer 14 are arranged. In all cases it is it is not necessary that the solid electrolyte 12 be so porous that it is gas permeable. Also in this In this case, the oxygen probe 8 arranged on the plate-shaped substrate 10 is securely arranged in the cavity 2c, in one end portion of the insulator 2 of the

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MSSAN MOTOR CO., LTD. TER MEER MÜLLER STEINMEISTER Case: GO89-8 0

Spark plug is molded.

Fig. 8 shows a further embodiment of the invention Spark plug with oxygen probe 8. In this one Case includes the oxygen probe 8, the oxygen partial pressure generating material 17, which is directly on the Surface of the cavity 2c is applied. Furthermore, the solid electrolyte 12, the measuring electrode 13 and the porous protective layer 14 is applied successively to the material 17. In this case, too, the comparison electrode 11 is applied directly to the surface of the cavity 2c molded into the insulator 2 of the spark plug on which comparison electrode 11 then successively the material 17 for generating the oxygen partial pressure, the solid electrolyte 12, the measuring electrode 13 and the protective layer 14 are applied.

The oxygen probe formed in this way or the In this way formed oxygen probe element has the following advantages: Since the probe 8 on a End portion of the insulator 2 of the spark plug is arranged, which is stable even under very severe conditions, it is possible to integrate the oxygen probe with the insulator of the spark plug, increasing the life of the Oxygen probe is significantly improved. Furthermore, the arrangement of the oxygen probe on the spark plug possible without making substantial changes to the structure of the conventional spark plug. In this In this case, it is not necessary to redesign the combustion chamber of the internal combustion engine. Furthermore, the Oxygen probe 8 in each combustion chamber of the internal combustion engine arranged so that the oxygen gas concentration in each combustion chamber is measured can be. As a result, this method enables the

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TER MEER · MÖLLER · STEINMEISTER

MSSAN MOTOR CO., LTD. Case: GO89-80

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Determination of the oxygen concentration an elegant and very precise measurement of the air / fuel ratio and a responsive feedback control of the Air / fuel ratio compared to the conventional one Method by which the concentration of gaseous oxygen in an exhaust pipe is measured, in which the exhaust gases from all cylinders of the internal combustion engine are combined.

In the above-mentioned various embodiments of the spark plug according to the invention, the measuring electrode and the reference electrode 11 are made of a catalytically active metal of the platinum group, such as ruthenium, palladium, rhodium, osmium, iridium, platinum and the like, or an alloy of these metals or an alloy of a metal the platinum group and a base metal. The electrodes can also be made of a catalytically inert material such as gold and silver or an oxide semiconductor such as SiC, TiO ₂ , CoO and LaCrO ₃ , or can also be made of an electrically conductive cermet made from a mixture of the above-mentioned metals and ceramic materials.

The electrode materials referred to above are applied to the surface of the insulator 2, the plate-shaped substrate 10 or the solid electrolyte 12 using physical deposition methods such as sputtering and ion plating, by electrochemical methods, such as Metallpiattieren _v or by a method which consists in a To print the paste and then burn it in.

The solid electrolyte 12 which conducts oxygen ions is made

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TER MEER ■ MÜLLER ■ STEINMEISTER

NESSAN MOTOR CO., LTD. Case: GO89-80

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from ZrO ", that rait CaO,

' ^Sr0 '

^W0 3 ^or

Ta ^ O., Is stabilized; or from Bi ₃ O .., which with Nb-O ₃ ,

SrO, WO,

or Y ₂ ° 3 is stabilized; or off

ThO "-Y" O or from CaO-Y ₃ O. These solid electrolyte materials are applied by physical application methods such as spraying and ion plating, electrochemical methods such as metal plating, or by printing a paste and baking the material in the form of a thin layer.

The material 17 for generating the comparison oxygen partial pressure consists of a mixture of a metal and a metal oxide, preferably a mixture of a metal and its oxide (Me-MeO). The material 17 can also consist of a mixture of metal oxides with different valencies (MeO-MeO-) or of a mixture of different metal oxides (MeO-Me ¹ O). According to the invention, it is preferred to use Ni-NiO, Cu-Cu ₂ O, Fe-FeO or the like as material 17 for generating the comparison oxygen partial pressure. The layer of material 17 is formed by physical application methods such as spraying and ion plating, electrochemical methods such as metal plating, or a process which consists in printing a paste and then baking it.

If you put the oxygen probe 8 on the plate-shaped Forming substrate 10, a plate-shaped substrate made of aluminum oxide, mullite, spinel or forsterite is used. The plate-shaped substrate 10 is in the form of a sintered body used, which is formed by pressing the powder or a corresponding unfired sheet.

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The protective layer 14 is formed from calcium zirconate, aluminum oxide or spinel and is plasma sprayed or with Using a method applied in which the material of the layer 14 by dipping and then Burning in applies.

Although only one oxygen probe has been shown and described with the above embodiments which has a solid electrolyte which conducts oxygen ions, it is also possible according to the invention for the oxygen probe to have an oxide semiconductor instead of the solid electrolyte. TiO 2 or CoO can be used as the oxide semiconductor. An example of this embodiment is shown in FIG. In this embodiment, a piece of the oxide semiconductor 18 made of CoO (or TiO ₂ ) is securely placed in the cavity 2c by adhering to the surface of the cavity 2c. The two connections 9a and 9b of the line 9 are embedded in the oxide semiconductor 18. The line 9 is connected to an electrical resistance measuring device 19. With this arrangement, when the oxygen concentration in a combustion chamber of the internal combustion engine changes, there is a change in electrical resistance as shown in Fig. 10, so that it becomes possible to measure the oxygen concentration in the combustion chamber. It goes without saying that the oxide semiconductor 18 can also be applied firmly to a plate-shaped substrate and / or covered with a protective layer.

The following examples serve to further illustrate the invention.

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example 1

To produce an insulator 2 of a spark plug, aluminum oxide containing 5% talc is brought with the aid of a Rubber pressing process into the desired shape and machine it to form an unfired structure with the final dimensions. During this stage of manufacture, a portion of an end section is cut the unfired structure is partially removed with the formation of the cavity 2c in which the oxygen probe 8 is arranged and continues to form 0.5-diameter through holes during rubber compression molding mm through which the lines 9 are passed.

Then, as shown in FIG. 11A, an unfired aluminum oxide sheet with the dimensions 4 × 4 × 0.5 mm is produced as a plate-shaped substrate 10. Then, a platinum paste is printed by screen printing on the surface of the unfired plate-shaped substrate 10 and then dried for one hour at 100 ⁰ C, to form the reference electrode 11 in the unfired state as shown in FIG. 11B. A pasty solid electrolyte is then screen-printed onto the unfired comparison electrode and then ^{dried for one hour at 100 °} C. in order to form the solid electrolyte 12 in the unfired state, as shown in FIG. 11C. Then, by screen-printing a platinum paste is printed on the surface of the unfired solid electrolyte and dried to the measuring electrode 13 to form for one hour at 100 ⁰ C in the unfired state as shown in FIG. 11D. As a result

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TER MEER · MÜLLER ■ STEINMEISTER

NISSAN MOTOR CO., LTD. Case: GO89-80

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a multi-layer oxygen probe is kept in the unfired state. The unfired oxygen probe is then inserted into the above-mentioned cavity 2c and firmly bonded to the surface of the cavity 2c using an aluminum oxide slip. Furthermore, a platinum suspension is passed through the through-hole 2b in order to produce the desired electrical connection. The structure is then ^{heat-treated for 2 hours at 1,600 °} C. in order to burn the insulator 2 and the oxygen probe 8 at the same time. Finally, the surface portion of the oxygen probe is covered with a spinel by plasma spraying to form a porous protective layer 14 on the surface of the oxygen probe 8, as shown in Fig. 11E.

Then, the spark plug is made using the one manufactured in this way and provided with the oxygen probe 8 Insulator 2 next to the center electrode 1, the metal body 4, etc. joined together in the manner as it is shown in FIG. The spark plug assembled in this way is placed in a combustion chamber an internal combustion engine arranged to determine the behavior of the spark plug in experimental investigations arranged oxygen probe 8 to evaluate.

In this experimental study, the positives and negative poles of the direct current source 15 in such a manner with the comparison electrode 11 and the measuring electrode 13 connected that a constant current of 3 μΑ flows through the electrodes. The internal resistance of these experimental investigations used tension measuring device is 1 M / l.

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NISSAN MOTOR CO., LTD. TER MEER MÜLLER - STEINMEISTER Case: GO89-80

The internal combustion engine is operated in this state, the output voltage characteristic shown in Fig. 12 is obtained. The one shown in FIG The curve illustrates the following: The output voltage is during the intake stroke and the compression stroke of the Cylinder of the internal combustion engine low due to the Fact that the partial pressure of oxygen in the air-fuel Mixture is high, which can also be seen from the figure. In contrast, it increases after ignition the air-fuel mixture through the spark plug's Oxygen partial pressure decreases rapidly, so that there is an output voltage of about 800 mV, as the air / fuel ratio is shifted slightly into the bold area. When the air / fuel ratio is negligible is in the lean range, the output voltage always has a value of less than about 100 mV. the output voltage characteristic obtained in this way is the same as that of a conventional oxygen probe, which is arranged in an exhaust pipe, so that it is confirmed that the oxygen probe of the present invention is effective in controlling the oxygen concentration in the combustion gas and or in the exhaust gas to measure in this way the air / fuel ratio to keep at the stoichiometric value.

The expected influence of the high voltage on the oxygen probe during the ignition process could not be observed. The influence was so small that the output voltage characteristic of the oxygen probe 8 is not influenced became.

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NISSAN MOTOR CO., LTD. TER MEER MÜLLER STEINMEISTER Case: GO89-80

Example 2

The spark plug with oxygen probe 8 produced according to Example 1 is installed in the first cylinder of a gasoline-powered 6-cylinder internal combustion engine and operates the machine at a speed of 5,200 min in a life test with high machine load. This shows that the oxygen probe 8 has a long service life, since there are no defects in the oxygen Have probe 8 locked.

As can be seen from the above, with the aid of the spark plug according to the invention, its insulator with an oxygen probe or an oxygen probe element is provided, which consists of a solid electrolyte which conducts oxygen ions or of an oxide semiconductor formed is possible the air / fuel ratio to be measured in every combustion chamber of an internal combustion engine. This enables precise feedback control the air / fuel ratio of each cylinder of the internal combustion engine possible, whereby a much more precise control of the air / fuel ratio of the Internal combustion engine is possible than with the conventional methods in which the control of the air / fuel ratio takes place as a function of the oxygen concentration, which is measured in an exhaust pipe in which the exhaust gases of all cylinders of the internal combustion engine are combined. Because the determination of the air / fuel ratio occurs immediately after the air-fuel mixture has burned, the feedback control can be used of the air / fuel ratio is reached instantly will. Furthermore, the spark plug according to the invention can be largely modified by only a slight change The spark plugs used are manufactured and only makes very little ones with an excellent service life Production costs required.

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Claims (20)

PATENT LAWYERS TER MEER - MÜLLER - STEINMEISTER Representatives admitted to the European Patent Office Prof. Representatives before the European Patent Office - Mandatalros agrees pres IOIfice europeen des brevels Dipl.-Chem. Dr. N. ter Meer Dipl.-Ing. H. Steinmeister Dipl.-Ing. F E. Müller Siekerwall 7, Triftstrasse 4, D-8000 MÖNCHEN 22 D-4800 BIELEFELD 1 Case: GO8 9-80 July 25, 1980 tM / kx NISSAN MOTOR CO., LTD. No. 2, Takara-cho, Kanagawa-ku, Yokohama City, Japan Spark plug with oxygen probe Priority: July 28, 1979, Japan No. 54-95573 PATENT CLAIMS Spark plug with a center electrode (1) surrounded by an insulator (2) and one with the center electrode (1) a side electrode (4c) forming a spark gap (6), characterized by an oxygen probe (8) arranged on the insulator (2) to determine the air / fuel ratio in the 130009/0742 Combustion chamber of an internal combustion engine via the oxygen concentration in the combustion chamber. 2. Spark plug according to claim 1, characterized in that the one in the Near the spark gap (6) arranged end of the generally cylindrically shaped insulator (2) a cavity (2c), in which the oxygen probe (8) is arranged is. 3. Spark plug according to claim 2, characterized by one in the insulator (2) arranged, in the direction of the axis of the generally cylindrically shaped insulator (2) extending through hole (2b) and a line arranged in the through hole (2b) and connected to the oxygen probe (8) (9). 4. Spark plug according to claim 1, characterized in that the oxygen probe (8) a comparison electrode (11), one arranged on the comparison electrode (11) and conducting oxygen ions, solid electrolyte (12) and one on top of the solid electrolyte (12) arranged measuring electrode (13). 5. Spark plug according to claim 4, characterized by a direct current source (15) which with the comparison electrode (11) and the measuring electrode (13) is connected to by causing movement of oxygen ions in the solid electrolyte (12) a Generate comparison oxygen partial pressure. 130009/0742 TER MEER · MÜLLER · STEINMEISTER rtlSSAN MOTOR CO. LTD. Case: GO89-80 6. Spark plug according to claim 1, characterized
characterized in that the oxygen probe (8) has a material (17) for generating a reference oxygen partial pressure, a reference electrode (11) arranged on this material, a solid electrolyte (12) arranged on the reference electrode (11) and conducting oxygen ions, and one the solid electrolyte (12) arranged measuring electrode (13). 7. Spark plug according to claim 1, characterized
It is shown that the oxygen probe (8) is formed from an oxide semiconductor. 8. Spark plug according to claims 1 or 7, characterized in that the oxygen probe (8) is arranged via a substrate plate (10) on the surface of the insulator (2) of the spark plug. 9. Spark plug according to claims 1 or 7, characterized in that the oxygen probe (8) is arranged directly on the surface of the insulator (2) of the spark plug. 10. Spark plug according to claims 4 or 6, characterized by at least one Porous protective layer (14) covering the measuring electrode (13) - 11. Spark plug according to claims 4 or 6, characterized characterized in that the comparison electrode (11) and the measuring electrode (13) from catalytic active materials are formed. 1 30009/0742 TER MEER · MÜLLER ■ STEINMEISTER NISSAN MOTOR CO., LTD. Case: GO89-80 12. Spark plug according to claims 4 or 6, characterized in that the comparison electrode (11) or the measuring electrode (13) made of a catalytically active or a catalytically inert one Material are formed. 13. Spark plug according to claims 11 or 12, characterized in that the catalytically active material is selected from the group consisting of the metals of the platinum group and alloys of platinum group metals, alloys containing a platinum group metal and a base metal, and electrically conductive cermets containing these metals. 14. Spark plug according to claim 13, characterized in that the metal of the Platinum group is selected from the group consisting of ruthenium, palladium, rhodium, osmium, and iridium Includes platinum. 15. Spark plug according to claims 11 or 12, characterized in that the catalytically inert material comprises at least one member from the group comprising gold, silver, SiC, TiO ₂ , CoO, LaCrO ^ and electrically conductive cermets made from these materials. 16. Spark plug according to claims 4 or 6, characterized in that the oxygen ions conductive, solid electrolyte (12) at least one -2 ^G 3 ' treter of the group of substances includes ZrO ₉ , Bi ^ O. ThO ₃ -Y ₂ O ₃ and CaO-Y ₃ O ₃ . 130009/0742 NISSAN MOTOR CO., LTD. TER MEER MÜLLER STEINMEISTER Case: GO89-80 17. Spark plug according to claim 6, characterized in that the material for generating the comparison oxygen partial pressure contains at least one member of the group of substances comprising Ni-NiO, Cu-Cu ₂ O and Fe-FeO. 18. Spark plug according to claim 8, characterized characterized in that the substrate plate (10) at least one member of the group of Contains substances including alumina, mullite, spinel and forsterite. 19. Spark plug according to claim 10, characterized in that the porous protective layer (14) is formed from a representative of the group of substances, the calcium zirconate, aluminum oxide and spinel. 20. Spark plug according to claim 7, characterized in that the oxide semiconductor is selected from the group comprising TiO ₂ and CoO. 130009/0742