DE2233573A1 - SPARK PLUG FOR COMBUSTION MACHINERY - Google Patents

Description

CHAMPION SPARK PLUG COMPANY, 900 Upton Avenue, Toledo, Ohio / USA

Spark plug for internal combustion engines

The invention relates to resistance elements and is directed in particular to an improved resistance element for suppressing high frequency radiation from a high-voltage ignition circuit of internal combustion engines.

The problem of eliminating high frequency radiation from high voltage ignition systems of internal combustion engines has recently increased in importance because of the malfunction of radio broadcasting channels for broadcasting and navigation. That The problem was made worse by the increasing number of automobiles, boats, and plug-in vehicles simultaneous increase in the use of radio frequency equipment both in broadcasting and in navigation.

Typical ignition systems for internal combustion engines included

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a set of breaker tips, a capacitor, an ignition coil, a spark plug and connecting wires. When the breaker tips are closed, a battery is connected and allows a current to flow into one The primary winding of an ignition coil, around which a magnetic field builds up, flows in an iron core in the ignition coil Stores energy. If the interrupter tips are opened, the magnetic field collapses and generates a high voltage on a secondary winding of the ignition coil. The high voltage is applied to an ignition gap in the spark plug and there forms an arc, which greatly reduces the impedance of the gap. The secondary coil winding and the low impedance ignition gap form a resonant circuit that oscillates when the stored in the core Energy disappears. These vibrations are in the high frequency spectrum and lead to loud noise and interference both in radio equipment and in navigation mode.

It has previously been found that random radio frequency radiation of ignition systems of internal combustion engines can thereby be reduced or even eliminated very easily can if you insert a resistance element in the high-voltage ignition circuit for each ignition coil. The resistance element may sit in the spark plug insulator bore in series with the spark plug center electrode or any other convenient place in the ignition system, for example in a distributor rotor, or can be used in the high frequency stacks be distributed.

The known resistors, except in the distribution cables, are generally carbon rod resistors, wound from wire Resistors made of sintered material

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Resistance rods or a fired resistance mass between glass seals in the center electrode bore through a spark plug insulator. Each of these different resistors has its advantages and disadvantages. The carbon capsule resistor, for example, is comparatively cheap compared to resistors wound from wire. However, if the carbon capsule resistor used in a spark plug and heated to for example about 23O ⁰ C (450 ° P) or more during operation of the machine, then the carbon tends to oxidize, resulting in an open circuit. For this reason, carbon resistors are not used in plug-in internal combustion engines, which operate at higher temperatures than automotive internal combustion engines and cannot tolerate errors. The carbon resistance also tends to fail because the resistance value depends on how tightly the carbon particles are packed, and thermal and electrical stresses can loosen these particles, which leads to failure. The wire-wound resistors do not have as great a drop in resistance at higher temperatures as carbon resistors and are therefore more effective suppressors. However, the wire wound resistors are expensive compared to the carbon resistors and there are problems both in the formation of the arc and in the connection of terminals to the wire ends. In addition, wire-wound resistors are blocky and difficult to use in small-sized spark plugs.

You also have resistance elements directly in the Center electrode hole of a spark plug insulator formed. One type of such resistance element consists of a resistor, that by pulping a resistor composition is made in the bore of a spark plug insulator.

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Such compositions are generally heterogeneous mixtures of conductive or semiconductive material such as Carbon, metal, metal oxides, metal carbides, or combinations thereof. The mixture is generally through a pair of conductive glass seals held in place. In another embodiment, the resistor composition suspended in a glass structure and the spark plug insulator is heated so that the composition fuses to form a solid resistance element.

According to the present invention, there is provided an improved resistive element for suppressing random radio frequency radiation made from internal combustion engines essentially from copper oxide. The copper oxide, one in the Heat destructible binders and up to 10 wt. # Of a plasticizer are pressed together, extruded or otherwise formed into a rod or capsule which is heated to the point that the copper oxide is in a Resistance element adhering together sinters and at the same time the binder is destroyed. The element can with Contact terminals are provided by applying metal coatings to the ends of the resistor element.

If the resistance element to about 23O ⁰ C (P ⁰ 450) heats or more during operation of an internal combustion engine, the resistance value drops to approximately 5% of the cold or room temperature resistance. Despite this drastic drop in resistance, the element is effective in suppressing high frequency or radio frequency radiation from ignition systems in internal combustion engines. The drastic reduction in resistance when the resistance element is heated makes the use of resistance

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elements are required that have a noticeably higher room temperature resistance value than it is used for carbon resistors. The high cold resistance leads to a high level of interference suppression during starting, where the machine has higher than normal high-frequency or radio-frequency radiation can generate. If the resistance element is heated while the machine is running, it falls Resistance at or below the normal resistance range for anti-interference resistors while it is effective as suppressor. Possess copper oxide interference elements have a cold resistance of the order of 25,000 to 30,000 ohms and above and are far more effective as carbon resistors with a resistance of 5000 ohms and at least as effective as 5000 ohm wire-wound resistors, while being manufactured at a lower cost can be and have significantly smaller dimensions than resistors wound from wire with 5000 ohms.

Thus, it is the primary object of the present invention to provide an improved resistance element for suppressing high or To create radio frequency radiation from ignition systems in internal combustion engines.

In addition, the invention is intended to create a spark plug which has an internal ignition noise suppression element comprises essentially of copper oxide.

The invention will be explained in more detail below with reference to the embodiment shown in the drawing. The drawings show in:

Fig. 1 is a partially sectioned side view a spark plug with an interference suppression element according to FIG

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6 of the present invention; and in

Pig. 2 shows an enlarged sectional view through an embodiment an interference suppression element according to the invention.

In the drawing and in the following description of the figures the following reference symbols are used to designate the specified parts:

10 spark plug 11 Resistance element 12th • Metal jacket 13th insulator U Center electrode assembly 15th Threaded part 16 Ground electrode 17th Electrode tip 18th Center hole 19th Connection 20th F _e der 21 Surface part 22nd Core part

In Fig. 1 is a conventional spark plug 10 with an internal resistance element 11 for suppressing high or Radio frequency radiation that may interfere with radio or navigation equipment. The spark plug 10 generally includes a tubular metal jacket 12, an insulator 13 mounted in the metal jacket 12, and a Center electrode assembly 14. The lower end of the metal shell 12 has a threaded part 15 for screwing into the head of an internal combustion engine. A ground electrode

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16 is welded to the lower end of the metal jacket 12 with an electrode tip 17 forming an ignition gap. The center electrode assembly 15 is mounted in a central bore 18 extending axially through the Insulator 13 extends and in the usual way comprises the center electrode tip 17, a connection 19, the interference suppression or resistance element 10 and a spring 20. the Eeder 20 is either between the resistance element 11 and the electrode tip 17 or between the resistance element 11 and the terminal 19 are compressed so that a electrical series connection between the terminal 19 and the electrode tip 17 is maintained.

According to the present invention, the resistance or interference suppression element 11 consists of a composition which contains essentially copper oxides. Particles of cuprooxide (CupU) or a mixture of cuprooxide and cuprioxide (CuO) with a particle size below 44 microns and preferably with an average size in the range of 6 to 13 microns are brought into the desired form of resistance and have been heated for so long and at a sufficient temperature, that they sinter together to form a cohesive mass. A copper oxide mixture within a range From 70 to 100% by weight of cuprooxide and 0 to 30% by weight of cuprioxide give a satisfactory result according to experience Ignition noise suppressor. A small amount, a heat-destructible binder, for example wax, starch, carboxycellulose, polyvinyl alcohol or Natural and synthetic rubber, can be added to the copper oxide particles to make the desired shape of resistor until the particles are sintered together. In a preferred embodiment is the binder ranges from 0.1 to 4 #. Additionally

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can use up to 10 # of an inert plasticizer, for example bentonite, colloidal silica or clay can be added to the copper oxide particles in order to improve the workability to enlarge the particles when they are deformed into the final shape of the suppressor element.

The final composition of the finished resistor or interference suppression element 11 is determined by various factors, primarily the initial composition and the particle size of the copper oxides, the pressure, the firing temperature, the firing atmosphere and the firing time. For example, if the initial mixture essentially contains cuprooxide, the finished resistor element 11 has a core structure. During the burning process, the oxygen from the surrounding air combines with the cuprous oxide to form cupric oxide. As in the section through a cylindrical resistance element 11 in Pig. 2, the cupric oxide layer is initially formed as a surface part 21 of the element 11. A core part 22 of the resistance element 11 remains essentially cuprous oxide, the composition of the starting mixture. The thickness of the surface part 21 made of cupric oxide is determined by the firing time and the firing temperature. If the resistance element 11 is burned for a sufficiently long time at a sufficiently high temperature, the core part 22 disappears and the resistance element consists essentially only of cupric oxide. It has for example been found that, as X-ray diffraction indicates mm in an element of 3.6 the whole Kuprooxid is converted into Kuprioxid when the element to 865 ⁰ C is heated (155o ⁰ P) for 30 minutes while only 20 % Kuprooxid be converted in a similar element in Kuprioxid when the element was heated at 455 ⁰ C for 30 minutes. The core part 22

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of the resistance element 11 naturally contains cupric oxide, when cuprioxide was present in the initial mixture from which the resistor element was formed. Will also The resistance element is heated to about 815 C or more, then the bentonite plasticizer is in aluminum silicate dehydrated. However, aluminum silicate is also essentially inert in the resistance or interference suppression element,

The actual resistance of a copper oxide element is very difficult to measure accurately because of the variable influence of the contact resistance at both ends of the Element. Where uniformity in the measured resistance is desired, conductive covers are placed on the ends of the resistance element 11, which is connected to the spring 20 and either make contact with the connection 19 or the electrode tip 17. The coating reduces the likelihood the occurrence of resistance contacts between the resistance element 11 and either the terminal 19 or the Electrode tip 17 and the spring 20. The coating is applied after the copper oxide particles into a coherent Mass are sintered. The coating may, for example, consist of one suspended in resin or in a paste Consist of silver powder. The coating is applied to the ends of the resistor and the resistor element becomes then fired at a temperature sufficient to deposit the silver on the ends of the sintered copper oxide resistor elements to burn open. However, the resistance or suppressor element 11 in the central bore of a spark plug mounted and a voltage comparable to the ignition voltage is applied, then the contact resistance is negligible, which eliminates the need to apply a conductive coating. The high voltage applied to the spark plug terminal 19 bridges or breaks any high resistance

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Status contact between the resistance element 11 and either the terminal 19 or the electrode tip 17 or the spring 20. This bridging affects the copper oxide element does not and does not lead to destruction.

The resistance or suppressor element can be in the usual Shape wisely. In the preferred embodiments, however, it is preferably formed either by extrusion or by extrusion Pressing into a mold. The preferred embodiments of a method for producing the resistance element are intended in are explained in more detail below with the aid of examples.

Example I.

Resistor elements were made by extrusion molding a mass consisting essentially of cuprous oxide particles plus binder and a plasticizer. The cupro oxide particles had the commercial quality of 95% purity and contained free copper and cupric oxide as impurities. The cupro oxide particles were sieved to below 44 microns in size and had an average size within the range of 6 to 13 microns. At least 0.1% by weight and up to 4% by weight of a binder composed of about 15 # isinglass and 85 # glycerine and 1 to 10% by weight bentonite as a plasticizer were added to the cupro oxide particles. To this mixture as much water was added that a moisture content of 6 to 15 $> resulted. The mixture was then filtered through a nozzle of 3 _t 5 mm (0.140 inches) in an extruder pressed and cut into bars with a length of approximately 6.35 mm (o, 25 inches). The Kuprooxidteilchen were sintered for 30 minutes in cohesive rod-shaped resistor elements by heating in an oven at 720 ⁰ C (1350 ⁰ F). The effects of contact resistance

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between the resistance elements and an outer circle were reduced by coating the contact ends of the resistance elements with a silver paste. The resistive elements were then fired again at 538 ^° G to burn in the silver on the ends of the elements.

Typical resistance elements made according to the above example were evaluated and it was found that the elements had a resistance value at room temperature of 6500 ohms - 1500 ohms. If the resistance elements were heated to a temperature in the normal operating range of 93 ⁰ C (200 ⁰ F) to 235 ⁰ C (45O ⁰ P), then the resistance fell to between 250 and 400 ohms, i.e. approx. 5 $> the room temperature resistance .

Example II

There were pressed from a mixture of resistance elements, not containing the substantially pure Kuprooxidteilchen with more than $ 5> impurities, 2 wt. # Of a paraffin binder and 1 wt.% Of bentonite as a plasticizer and suspending agents. Before pressing, the mixture was formed into spherical elements of 200 microns standard size by a conventional spray drying process in order to improve the flow properties of the mixture. The spheres were then placed in a mold where they ^{were pressed at pressures between 780 to 5500 kg / cm 2} (5 to 35 tons per inch ² ), so that resistance elements with a diameter of 3.5 * mm (0.140 inch) and approximately 6.35 mm (0.25 inch) in length. As the resistance elements were heated for 30 minutes at 720 ⁰ C (135 ° F ^0), to sinter the Kuprooxidteilchen while aufzubrennen the binder in Example. 1

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The typical resistance elements obtained according to the above example were evaluated and again showed a resistance at room temperature in the range of 6500 ohms - 1500 ohms. In the Working temperature in the range of 92 ⁰ C (200 ⁰ F) to 235 ⁰ C (45O ⁰ F), the resistance value of the room temperature resistance fell to approximately 5%.

To suppress radio or high-frequency radiation from the ignition system of an internal combustion engine with the efficiency of a wire-wound resistor of 5000 ohms, sintered copper oxide elements with a room temperature resistance of at least 25,000 ohms were used in series in the center electrode of a spark plug. When the spark plug insulator and the internal resistance ^{were heated to a working temperature of approx. 93 0} C (200 ⁰ F) up to 235 ° C (450 ⁰ F), then the resistance value fell to approx. 5% of the cold value or to approx. 1250 ohm or more depending on the cold temperature resistance value. The resistance elements were suitable as ignition noise suppressors with the low resistance value.

Example III

There have been various different suppressors or resistance elements made mainly of cuprooxide and made from mixtures containing essentially cuprooxide and up to 30% by weight cuprioxide. The cuprous oxide particles and the cuprioxide particles had an average diameter of 10 microns. In any case it was

1 wt. # Bentonite as an inert plasticizer and

2% by weight of polyvinyl alcohol added as a temporary or temporary binder. The items were at

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Print between 2600 and 7500 kg / cm ² (15 to 47.5 t / in ² ) in cylinders with a diameter of 3.5 mm and a length of 6.35 mm and then pressed by firing at 455 ⁰ C (85O ⁰ P) for 30 minutes and finally ^{sintered at 815 0} C (1500 ⁰ F) for 6 minutes.

In analyzing the sintered elements, sheet resistance values ranging from 30,000 ohms to 120,000 ohms were measured with a 500 volt megohm meter at 9 kg (20 pounds) clamp pressure at the opposite ends of each cylinder. If the elements were inserted into the center electrode arrangement in spark plugs and operated in internal combustion engines, then at least in terms of their effect they were comparable to wound wire resistors of 5000 ohms in terms of suppressing the ignition noise. The effectiveness of the various elements as suppressors and the resistances of the elements evidently had no relation to the final composition of the elements. X-ray analysis indicated that the overall composition of the finished elements ranged from 50:50 molar ratio to 70:30 molar ratio of cuprooxide to cuprioxide. The final composition was affected by the molding pressure. A first group of elements made from essentially $ 100 euprooxide exhibited a cuprooxide: cupric oxide molar ratio of 54:36 under a pressure of 2360 kg / cm (15 tons / inch), while a second group of elements made from the same starting mixture at a pressure of 3950 kg / cm ² (25 t / in ² ) had a molar ratio of 63:37 and a third group of elements from the same initial mixture at a pressure of 6600 kg / cm (42 t / in ² ) had a molar ratio of 70:30 would have. The molding pressure also affected the mechanical strength of the finished elements. Regarding the above three groups of elements, those produced at 2360 kg / cm (15 t / inch)

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presented elements destroyed under an axial load of 18 kg, the ^{elements manufactured at 3950 kg / cm 2} (25 t / inch ² ) at an axial load of approx. 22.5 kg and those manufactured at 6600 kg / cm ² (42 t / inch 2) Zoll ² ) manufactured elements with axial loads of approx. 29 kg,

Example IV

Two sets of elements were made up essentially of cuprous oxide particles having an average diameter of 6 microns. 1% by weight of bentonite and 2% by weight of polyvinyl alcohol were added to the particles as a plasticizer or as a temporary binder. This mixture was then molded into 200 micron sized spheres. The elements were then formed into 3.5 mm (0.142 inch) diameter and 6.35 mm (0.250 inch) cylinders by pressing at 2360 kg / cm ² . The first group was heated to 815 ° C. for 6 minutes and the second group to 815 ^° C. for 30 minutes.

An analysis of the elements showed that the elements of the first group had a cold resistance of the order of magnitude of 300,000 ohms and the elements in the second group have a cold resistance of the order of 50,000 to 55,000 ohms. The elements of both groups were comparable with wound wire resistors of 5000 ohms for the suppression of the ignition noise of internal combustion engines when installed in the center electrode arrangement of spark plugs. An X-ray analysis also showed that the overall composition of the elements in the first The group consisted essentially of copper oxide with a 20:80 molar ratio of cupro oxide to cupric oxide. the Elements of the second group consisted essentially of 100 # cupric oxide plus aluminum silicate from the dehydrated one Bentonite. A better mechanical bond resulted

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the longer heating in the second group. An average axial load of 30 kg was required to shatter the elements in the second group, while an average axial load of only 23 kg was required to handle the elements of the first group to smash.

The sintered copper oxide resistor or suppressor elements had various inexplicable properties. It has been shown that some resistor materials, 'which have a drop in resistance similar to that of sintered Copper oxides are unsuitable as suppressors. For example, barium ferrite resistors worked with the same resistance values under working conditions not as a radio frequency suppressor. It was also found that the suppressor properties of sintered copper oxide elements do not appear to be linear at low voltage. This means that a 30,000 ohm (KaIt) resistor is not as effective as, for example, a 20,000 ohm (cold) resistor or a 40,000 ohm resistor (also cold). The reason for this apparent non-linearity has not yet been found. The apparent non-linearity, however, arises from a difficulty in giving accurate low voltage resistance measurements of copper oxide elements.

Suppression elements have also been manufactured in one piece in spark plug insulators by adding mixtures contained in the consisted essentially of copper oxide, introduced into the center electrode hole and burned the insulator. There the insulator prevents the oxygen present in the air from coming into contact with the mixture while burning to come, the cuprooxide was not converted to cuprioxide during the firing process. As a result, one received

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better results by using cupric oxide or a mixture of cupric oxide and cuprous oxide as the starting material. However, cuprioxide on its own is difficult to use. sinter and one needs higher firing temperatures and longer firing times, for example one burning for a time from 15 minutes to 2 hours at 815 ⁰ C (1500 ⁰ P) to 980 ⁰ C (1800 ⁰ P).

Of course, various modifications can be made in the method of making a sintered copper oxide interference element and when using such an element, without departing from the scope of the invention.

- patent claims -

309808/0766

Claims (16)

Claims / 1V, spark plug for internal combustion engines with a hollow, Tubular jacket and one housed in this jacket Insulator which has a bore for receiving a center electrode arrangement, characterized in that the center electrode arrangement (14) an ignition tip (17), a connection (19) / a sintered one consisting essentially of copper oxide Mass (11) and this mass (11) electrically connected in series between ignition tip (17) and connection (19) connecting device having. 2. Spark plug according to claim 1, characterized in that the essentially made of copper oxide existing mass (11). essentially cylindrical shape with for the electrical connection with the ignition tip (17) and the Terminal (19) provided opposite ends. 3. Spark plug according to claim 1 or 2, characterized in that the connecting device contains electrically conductive coatings on the opposite "ends of the cylindrical copper oxide mass (11). 4. Spark plug according to claim 3, characterized in that the coatings consist of silver. 5. Spark plug according to one or more of the preceding claims, characterized in that that the sintered mass (11) 10% of an inert plasticizer - 18 309808/0766 - Contains 18 agents. 6. Spark plug according to claim 5, characterized in that the plasticizer is bentonite is. 7. Spark plug according to one or more of the preceding claims, characterized in that the connecting means one between the sintered copper oxide mass (11) and the ignition tip (17) or the connection (19) has inserted spring (20). 8. Spark plug according to one or more of the preceding claims, characterized in that the sintered mass (11) consists essentially of cupric oxide. 9. Spark plug according to one or more of claims 1 to 7, characterized in that the sintered mass (11) consists of cupric and cupro oxide. 10. Spark plug according to claim 9, characterized in that the surface parts (21) of the sintered Composition (11) made of cuprioxide, which enclose a core part (22), which consists essentially of Cuprooxide is made. 11. Process for the production of an ignition noise suppression element for use in the high-voltage ignition system of internal combustion engines, characterized in that a) a mixture is made from - 19 - 309808/0766 (1) 96 to 99.9 wt. $ Copper oxide particles having a Size not exceeding 44 microns that contain 70 to 100 wt. # Cuprooxide and 0 to 30 wt. # Cupric oxide and (2) o, 1 to 4% by weight of a binder. (b) that the mixture is molded into the predetermined shape j and that (c) this formed mixture for a sufficiently long time and with sufficiently high temperature is heated so that the copper oxide particles sinter into an adherent mass. 12. The method according to claim 11, characterized in that 1 to 10 wt.% Of an inert Plasticizer and 6 to 15 wt. # Water to the Mixture are added and the! Shaping is done by extrusion. 13. The method according to claim 11, characterized in that g e k e η η ζ ei c hn e t that 1 to 10% by weight of an inert plasticizer are added to the mixture and the Shaping is done by pressing. 14. The method according to claim 13, characterized in that the mixture and the plasticizer so much water is added that a slurry is formed and that the mixture is in spheres before deformation is spray dried. . 15. The method according to claim 11, characterized in that on the ends of the sintered mass - 20 309808/0766 - 20 electrical, conductive contact surfaces are applied. 16. The method according to claim 11, characterized in that silver coatings are applied to the end parts of the sintered mass and the sintered mass is heated again to bond the silver coatings on it. 309808/0766