CN101479900A - Composite spark plug - Google Patents

Abstract

A composite ignition device includes a positive electrode having a tip formed thereon that is bonded to a first insulator to form a firing cone assembly. A second insulator having a negative capacitive element embedded therein is attached to the firing cone assembly. A positive capacitive element is disposed in the second insulator and is separated from the negative capacitive element by the second insulator. The positive capacitive element is coupled to the positive electrode. The positive and negative capacitive elements form a capacitor. A resistor is coupled to the positive capacitive element. An electrical connector is coupled to the resistor and attached to the second insulator. A shell includign a negative electrode having a tip is attached to the second insulator and the firing core assembly and coupled to the negative capacitive element. The negative electrode tip is spaced apart from the positive electrode tip.

Description

Composite spark plug

Cross References to Related Applications

This application claims priority and benefit to US Provisional Patent Application Serial No. 60/799,926, filed March 12, 2006, entitled "Composite Spark Plug," the specification of which is hereby incorporated by reference.

Background technique

This invention relates to spark plugs for igniting fuel in internal combustion spark ignition engines. Modern spark plug technology dates back to the early 1950s without any significant design changes other than the material and construction of the spark gap electrode. These relatively new electrode materials, such as platinum and iridium, have been designed into them for extended service life in order to mitigate the corrosion problems that are common to all spark plug electrodes. While these materials will reduce the electrode corrosion of a typical low power discharge (peak discharge current less than 1 amp) spark plugs and can run for the ¹⁰⁹ cycles required, they cannot withstand the high Coulombs of a high power discharge (peak discharge current greater than 1 amp). send. Additionally, many efforts have been made to create higher capacitance on the spark plug or to connect capacitors in parallel with existing spark plugs. But this will increase the discharge energy of the spark, and this design is inefficient, complex, and unable to handle the accelerated corrosion associated with high power discharges. No effort has been made to use foreign materials in the module assembly to create insulation for the spark plug.

US Patent No. 3,683,232, US Patent No. 1,148,106, and US Patent No. 4,751,430 discuss the use of capacitors or accumulators to increase spark energy. The electrical dimensions of the capacitor that will determine the discharge energy are not disclosed in these patents. Also, if the capacitor has a large enough capacitance, the voltage drop between the ignition transformer output and the spark gap can prevent the gap from ionizing and sparking.

US Patent No. 4,549,114 claims that the energy of the primary spark gap can be increased by incorporating a secondary gap in the spark plug body. The use of two spark gaps in a single spark plug to ignite fuel in any internal combustion spark ignition engine utilizing electronic processing to control fuel delivery and ignition timing can prove fatal to the operation of the engine. Because the EMI/RFI emitted by these two spark gaps can cause the CPU to malfunction.

In US Patent No. 5,272,415, a capacitor connected across a non-resistive spark plug is disclosed. Capacities are not disclosed, and there is no mention anywhere of electromagnetic and radio frequency interference from non-resistive spark plugs, which could cause a CPU shutdown or even a permanent destroy.

US Patent No. 5,514,314 discloses increasing spark size by creating a magnetic field in the positive and negative electrode regions of the spark plug. Said invention also claims to be able to fabricate monolithic electrodes, monolithic coils and capacitors, but does not disclose the resistivity value of the overall conductive path that generates the various electrical components. The resistivity value of the electrical component conductive path is designed to be 1.5-1.9 ohm/meter for proper functioning. Any reduction in vias caused by drift of the ceramic material inherent in the ceramic ink degrades the efficiency and performance of the electrical device. In addition, there is no mention of the cut-off voltage of the insulating medium that is relatively isolated from the charging conduction path of the monolithic component. If a standard ceramic material, such as 86% alumina, is used as the spark plug insulator, the dielectric strength or cutoff voltage is 200 volts/mil. The standard operating voltage range for spark plugs in internal combustion spark ignition engines is from 5Kv to 20Kv, and a peak of 40Kv can be seen in newer car ignitions, which will prevent monolithic electrodes, integral coils and capacitors from operating at this voltage level. lower insulation.

U.S. Patent No. 5,866,972, U.S. Patent No. 6,533,629, and U.S. Patent No. 6,533,629 refer to all of these by various methods and devices, electrodes and/or electrode tips composed of platinum, iridium or other noble metals that impede wear associated with spark plug operation. said application. These applications may not be sufficient to prevent electrode wear associated with high power discharges. As the electrodes wear, the voltage required to ionize the spark gap and create a spark increases. The ignition transformer or coil is limited by the amount of voltage delivered to the spark plug. The increase in the spark gap caused by accelerated corrosion and wear can be greater than the voltage drawn from the transformer, which can lead to misfire and damage to the catalytic converter.

US Patent No. 6,771,009 discloses a method of preventing sparkover and does not address the problems associated with electrode wear or increased sparkover energy.

US Patent No. 6,798,125 mentions the use of a higher temperature resistive nickel alloy as a base electrode material to which a noble metal is welded. The main claim is a nickel-based electrode material that guarantees weld integrity. This combination is said to reduce electrode corrosion, but it is not claimed to reduce corrosion or increase spark energy under high power discharge conditions.

US Patent No. 6,819,030 for spark plugs claims to reduce the temperature of the ground electrode, however, does not claim to reduce electrode corrosion or increase spark energy.

Contents of the invention

A composite ignition device for an internal combustion engine of the present invention includes a positive electrode having a tip formed at an end thereof, the tip being bonded to a first insulator to form an ignition cone assembly. The ignition device includes a second insulator including a negative capacitive element embedded therein and attached to the ignition cone assembly. The positive capacitive element is disposed in the second insulator and is isolated from the negative capacitive element by the second insulator. A positive capacitive element is connected to the positive electrode. The positive and negative capacitive elements form a capacitor. A resistor disposed in the resistive insulator is connected to the positive capacitive element through a resistive connector. An electrical connector is connected to the resistor and attached to the second insulator, and the housing is attached to the second insulator and ignition cone assembly and connected to the negative capacitive element. The case includes a negative electrode having a tip formed thereon and spaced from the tip of the positive electrode.

Alternatively, a second insulator is attached to the ignition cone assembly, and the negative capacitive element is embedded in the second insulator by injection molding or by insert molding. Alternatively, the second insulator comprises an engineering polymer. The engineering polymer may be a liquid crystal polymer or polyether ether ketone, and may have a dielectric constant between about 5 and about 10.

Alternatively, the first insulator comprises an aluminum oxide material. The alumina material may comprise about 88% to about 99% pure alumina. Alternatively, the resistive connector includes a spring member. Alternatively, the positive and negative electrode tips include rhenium and tungsten sintered materials. The material may be made of about 50% rhenium and about 50% tungsten or about 75% rhenium and about 25% tungsten. Alternatively, the positive electrode further includes a conductive ink coating on an outer surface thereof, the coating having a predetermined thickness. Conductive inks may include precious metals or precious metal alloys. Alternatively, the capacitor has a predetermined capacitance in the range of about 30 to about 100 picofarads (pf). Alternatively, the positive capacitive element is connected to the positive electrode by an interference fit.

In another embodiment, the present invention provides a circuit for an ignition device of an internal combustion engine, said circuit comprising a power source for intermittently activating said circuit, a positive electrode having a tip at its end, and a ground connected to ground. An electrode, the end of the ground electrode has a tip. The ground electrode tip is spaced from the positive electrode tip by a predetermined spark gap. The circuit also includes at least one resistor in series with the power supply and the positive electrode, and at least one capacitor connected directly to the resistor in parallel with the positive electrode and ground.

Alternatively, the at least one resistor reduces radio frequency interference (RFI) when the circuit is active. Alternatively, the at least one capacitor increases the peak current of the spark gap when the circuit is active. Alternatively, the positive and negative electrode tips include rhenium and tungsten sintered materials. The material may be made of about 50% rhenium and about 50% tungsten or about 75% rhenium and about 25% tungsten. Alternatively, the resistor has a predetermined resistance value in the range of about 2 kilo-ohms (kohms) to about 20 kilo-ohms (kohms). Alternatively, the capacitor has a predetermined capacitance in the range of about 30 to about 100 picofarads (pf).

In another embodiment, the present invention provides a method of forming a composite ignition device for an internal combustion engine, the method comprising bonding a positive electrode including a tip formed thereon to a first insulator to form an ignition cone body assembly, the negative capacitive element is embedded in the second insulator and the second insulator is connected to the ignition cone assembly, and the positive capacitive element is connected to the positive electrode in the second insulator. The positive capacitive element is isolated from the negative capacitive element by the second insulator, and the positive and negative capacitive elements form a capacitor. The method also includes disposing a resistor in the resistive insulator, attaching the resistor to the positive capacitive element through a resistor connector, attaching an electrical connector to the resistor, attaching the electrical connector to the first A second insulator, attaching the housing to the second insulator and ignition cone assembly, and connecting the housing to the negative capacitive element. The case includes a negative electrode having a tip formed thereon, the negative electrode tip being spaced apart from the positive electrode tip.

Alternatively, the method further comprises sealing the top of the electrode in an insulator. Alternatively, the method further comprises coating the positive electrode with conductive ink prior to bonding the positive electrode to the first insulator. Conductive inks may include precious metals or precious metal alloys. Alternatively, the step of attaching the housing to the second insulator and ignition cone assembly includes folding the housing towards the second insulator and ignition cone assembly. Alternatively, the step of connecting the housing to the negative capacitive element comprises crimping the housing towards the negative capacitive element.

Alternatively, the step of bonding the positive electrode to the first insulator includes heating the positive electrode and the first insulator at a predetermined temperature for a predetermined time. The predetermined temperature may be about 750 degrees Celsius to about 900 degrees Celsius, and the predetermined time may be about 10 minutes to about 60 minutes.

Alternatively, the steps of embedding the negative capacitive element in the second insulator and attaching the second insulator to the ignition cone assembly include injection molding or insert molding. Alternatively, the second insulator comprises an engineering polymer. Engineering polymers may include liquid crystal polymers or polyetheretherketone, and may have a dielectric constant between about 5 and about 10.

Alternatively, the first insulator comprises an aluminum oxide material. The alumina material may comprise from about 88% to about 99% pure alumina. Alternatively, the resistive connector includes a spring member. Alternatively, the method further includes forming the sintered material by sintering rhenium and tungsten to form the positive and negative electrode tips. The material may be made of about 50% rhenium and about 50% tungsten or about 75% rhenium and about 25% tungsten. Alternatively, the capacitor has a predetermined capacitance in the range of about 30 to about 100 picofarads (pf). Alternatively, the step of connecting the positive capacitive element to the positive capacitive element is achieved by an interference fit.

The present invention provides an ignition device or spark plug for a spark ignition internal combustion engine, said ignition device or spark plug comprising a capacitive element or capacitor forming or integral with an insulator to enable the surge phase of the spark to occur During this period, the value of the current is the largest, thereby making the value of the spark electric energy the largest. The additional increase in spark energy creates a large flame kernel and ensures consistent ignition cycle-to-cycle with respect to crank angle. With proper use of the circuit, the breakdown voltage of the spark gap will not change, the timing of the spark will not change, and the overall spark period will not change.

In operation, when the capacitor is connected in parallel with the circuit, the ignition pulse is exposed to both the spark gap and the capacitor of the spark plug. When the voltage across the coil rises inductively to overcome the resistance in the spark gap, energy is stored in the capacitor if the resistance in the capacitor is less than the resistance in the spark gap. Once the resistance in the spark gap is overcome via ionization, the counter resistance between the spark gap and the capacitor triggers the capacitor to rapidly discharge the stored energy across the spark gap between one and ten nanoseconds, So that the current and thus the spark energy reach the maximum value.

The capacitor charges to the voltage level required to break down the spark gap. As engine load increases, vacuum decreases, which increases air pressure across the spark gap. As the pressure increases, the voltage required to break down the increased spark gap, the capacitor charges to a higher voltage. The final discharge takes the peak to a higher energy value. As the charging of the capacitor occurs simultaneously with the rising of the coil voltage, there is no delay in the timing event.

The capacitive element preferably comprises two oppositely charged electrically conductive cylindrical plates, wherein the ground plate is fully encased in the engineering polymer during the insertion or over molding process. The negative plate is exposed in a small circumferential area at the large diameter of the composite insulator in contact with the conductive steel housing of the spark plug. This exposure allows physical, mechanical and electrical contact, effectively placing the plate in the ground circuit of the electrical system.

The positive plate of the capacitive element is also the center conductor of the spark plug, which is directly connected via a resistor or inductor from the ignition coil or coil to the high voltage lead. During the forming process, the conductor is inserted into the central cavity of the composite insulator with an interference fit. An interference fit of .0005"-.001" is preferably required to establish the mutual relationship of the conductive plates to establish consistent capacitance. The insertion of the center conductor also makes electrical and mechanical contact with the center electrode of the spark gap.

Using a molding process of engineered polymers, the ceramic combustion cone containing the center electrode of the spark gap is positioned and secured to the capacitive element negative plate of the spark plug. Preferably, the molding process is an injection molding process or an insert molding process as understood by those skilled in the art. The insertion of the center conductor completes the capacitor and provides the connection between the spark plug and the ignition coil. Capacitance can vary from 10 picofarads to 100 picofarads, depending on the geometry of the plates, their mutual spacing, and the dielectric constant of the insulating engineering polymer.

It is preferable to offset the ends of the capacitor plates, which can compromise the dielectric strength of the engineered polymer insulator and can lead to sudden failure of the spark plug, in order to prevent enhancement of the electric field at the plate terminations. The ignition charge can break down the insulator at the point where the pulse flows directly to ground, bypassing the spark gap and creating permanent spark plug failure.

The present invention also provides a spark plug for a spark ignition type internal combustion engine, said spark plug being provided with an electrode material mainly composed of rhenium and tungsten sintered. Sintering mix percentages may range from 50% rhenium and 50% tungsten to 75% rhenium and 25% tungsten. Pure tungsten would be an ideal electrode material due to its conductivity and density, but would not be a good choice for internal combustion engine applications because the oxidation temperature of pure tungsten is lower than the combustion temperature of fossil fuels. Additionally, recent engine designs use lean burn, which has higher combustion temperatures, making tungsten a less acceptable electrode material. During oxidation, due to its volatility at the oxidation temperature, the tungsten electrode will corrode at a faster rate, reducing the useful life. By sintering tungsten with rhenium, the oxidation process of tungsten is prevented and the expected effect of reducing corrosion in high power discharge applications can be obtained.

Using noble metals as electrodes to meet composite specifications, as currently practiced in the industry, will not achieve the required mileage requirements at high spark energy operation. The increased discharge energy will increase the corrosion rate of the noble metal electrodes and cause misfires. In all misfire situations, burnout or destruction of the catalytic converter will occur.

Although the use of a rhenium/tungsten sinter mixture will mitigate the occurrence of oxidative corrosion, the high energy of the spark discharge will still corrode the electrodes at a faster rate than conventional ignition. The electrodes placed in the insulator are completely embedded in the insulator using a spark phenomenon called electron creep, exposing only the very ends and the surface of the electrodes. When the electrode embedded in the insulator is new, the spark occurs directly between the embedded electrode and the rhenium/tungsten tip or button attached to the ground plate of the negative electrode. Since the embedded electrode is corroded due to use under high-power discharge, the electrode will start to stretch or corrode from the surface far away from the insulator. In this case, once ionization occurs and a spark occurs, electrons from the ignition pulse will be emitted from the positive electrode, drift to the sides of the exposed electrode cavity, and jump onto the negative electrode.

The electrons require very little voltage to drift forward, or ionize, on the inner surface of the electrode cavity. This design allows the electrodes to withstand corrosion beyond the operating limits of the ignition system, however, maintaining a breakdown voltage with a smaller gap between the electrodes. In this way, the larger gaps, corroded from continuous operation under high power discharge, perform like the original gaps in the sense that the voltage level does not exceed the output voltage of the ignition system, thus for the required mileage prevents misfires.

The invention also provides a structure by which high power discharges are influenced and radio frequency interference normally associated with high power discharges is suppressed. Using a capacitor connected in parallel across the spark gap to charge to the breakdown voltage of the spark gap and then quickly discharge it during the surge phase of the spark will exponentially increase the energy of the ignition spark compared to that of a conventional ignition . The main reason for this is the total resistance in the ignition secondary circuit.

Much progress has now been made in the secondary circuit of the ignition by eliminating the high voltage wires between the coils and the spark plugs, and by utilizing a single coil in each cylinder allowing greater efficiency of electrical transfer. However, there is still significant drag in the spark plug that makes the transfer efficiency of a typical automotive ignition less than 1%. By replacing the resistive spark plug with a zero resistance, the electrical transfer efficiency of the ignition energy can be increased to about 10%. Adding an appropriately sized capacitor further increases the transfer efficiency to over 50%. The greater the efficiency of electrical transfer, the greater the amount of ignition energy coupled to the fuel supplied, and the higher the combustion efficiency, these may require the use of non-resistive spark plugs to achieve very high transfer efficiencies. However, the use of non-resistive spark plugs creates radio frequency and electromagnetic interference (RFI), which is amplified by the very hard discharge of the capacitor. This is unacceptable because RFI at these energy levels and frequencies is not compatible with the operation of the car computer, which is why resistive spark plugs are generally accepted by primary equipment manufacturers.

The present invention also provides a circuit that includes a resistor of preferably 5KΩ that will suppress any high frequency electrical noise without affecting the high power discharge. Crucial to RFI suppression is placing the resistor close to the capacitor inside the secondary circuit of the ignition system. One end of the resistor is directly connected to the capacitor and the other end is directly connected to a terminal which is connected to the coil in a coil-on-plug or from the coil to a high voltage cable. In this way, the excitation load circuit is isolated from any resistance, the excitation is now a capacitor, and the load is a spark gap. When the resistance in the capacitor is greater than that of the spark gap, once discharged, the coil pulse bypasses the capacitor and is delivered directly across the spark gap. This placement allows the high voltage pulse to be delivered entirely into the spark gap without affecting spark duration.

The invention also provides a connector for connecting the negative capacitor plate to a ground circuit. Any inductance or resistance in the capacitor junction will reduce the efficiency of the discharge, resulting in a reduction in the energy coupled to the fuel supply. During the forming process, the circumferential ring of the cylindrical plate at the large diameter of the insulator is exposed. Said ring makes positive mechanical and electrical contact with the housing of the spark plug. Appropriate threads are provided on the metal conductive housing to enable mounting to the head of the internal combustion engine. When said head is mechanically attached to the engine block, which is connected to the negative terminal of the battery through a ground plate, grounding of the negative plate of the capacitor can advantageously be achieved by positive mechanical contact with the spark plug housing.

The invention also provides a junction to the positive plate of the capacitor that provides a non-resistive path from the ignition pulse to the center, positive electrode of the spark gap. This is accomplished by using the center conductor of the spark plug as the positive plate. A center conductor, preferably made of a tubular highly conductive material, such as aluminum or copper, is inserted into the central cavity of the insulator using an interference fit and engages the extension of the positive electrode when fully inserted.

The present invention also provides a positive gas seal for the internal components of the spark plug to isolate the gases and pressures generated by the combustion process. The ceramic cone exposed to the insulator of the combustion chamber is provided with a core in which the center electrode is mounted. The electrode is provided with an extension opposite the end exposed to the combustion chamber for engaging the center conductor and the positive plate of the capacitor. The base of the extension is an annular boss extending into the ceramic cone or a flanged pipe joint, which uses ceramic epoxy, copper glass or other suitable high-temperature sealants to seal the electrodes to isolate combustion gases.

Description of drawings

Objects and features of the present invention will become more clear from the following description of preferred embodiments given with reference to the accompanying drawings, in which:

Fig. 1 is a cross-sectional view of an ignition device embodiment for an internal combustion spark ignition engine of the present invention;

Figure 2A is a partially exploded cross-sectional view of individual components over-molded with an engineering polymer to form the insulator of the spark plug;

Figure 2B is a top view of the capacitive element shown in Figure 2A;

Fig. 3 is the cross-sectional view of composite insulator of the present invention;

Figure 4 is a partially exploded cross-sectional view of the individual components including the positive plate and center electrode assembly of the capacitor element;

Figure 5 is a cross-sectional view of the insulator assembly of the ignition device of the present invention; and

Fig. 6 is a circuit diagram of the ignition device of the present invention.

Detailed ways

Referring now to the drawings, and in particular to FIG. 1 , a spark plug or ignition device for a spark ignition internal combustion engine of the present invention is shown generally at 1 . The spark plug or ignition device 1 consists of a preferably metallic case or housing 15 having a generally cylindrical base 44 on which external threads 18 may be formed for use with a spark ignition internal combustion engine ( not shown) to the cylinder head (not shown). The cylindrical base 44 of the spark plug housing has a generally flat plane perpendicular to the longitudinal axis of the spark plug 1, on which plane the ground electrode 16 is attached, preferably by conventional welding methods. In one embodiment of the invention, the ground electrode 16 has a preferably rounded tip 45 of a Rhenium/Tungsten sintered compound, which prevents corrosion of the electrode 16 due to high power discharges, as further disclosed herein.

The spark plug or ignition device 1 comprises a preferably hollow composite insulator 4 arranged concentrically inside a housing 15 in combination with a combustion cone 5 preferably made of ceramic or the like. A central or positive electrode 7 is arranged concentrically inside the ceramic cone 5 which is placed in the combustion chamber when installed in an engine (not shown).

The center electrode 7 is preferably made of a thermally and electrically conductive material of low resistivity value, such as, but not limited to, copper or a copper alloy with or without an external coating, cladding or plating of a nickel alloy. The center electrode 7 preferably includes an electrode tip 17 formed thereon by a welded structure or by other suitable attachment structure, said electrode tip preferably being made of a rhenium/tungsten alloy (50%-75% rhenium), which is High corrosion resistance under high power discharge conditions, as further disclosed herein.

The spark plug 1 comprises a highly conductive spring 10 which is an element of the center conductor assembly and the positive plate 43 of the capacitive element. The spring 10 is connected to one end of a resistor or inductor 11, preferably 5KΩ (or a suitable resistance value), and electrically and mechanically contacts the positive plate 43 of the capacitor, which is connected by a stud bolt ( stud) 9 and the positive plate 43 interference fit and connected to the center electrode 7. Preferably, a resistor or inductor 11 is connected to a high voltage terminal 13 for further connection to an ignition coil (not shown) through a through rod 14 of terminal 13 .

The composite insulator 4 of the spark plug is inserted into the housing 15 and is preferably crimped for alignment and sealing from combustion gases, as is commonly done in the industry. Preferably, the flange 3 of the negative plate 2 is exposed during the overmolding process for manufacturing the insulator 4 . When the housing 15 is crimped on its side and pressed down on the insulator 1 using conventional industry practices, the exposed flange 3 of the negative plate of the capacitor 2 makes physical and electrical contact with the conductive housing 15 of the spark plug. The mechanical contact between the housing 15 and the capacitor negative plate 2, which is electrically connected to the ground circuit of the engine ignition circuit, advantageously ensures that the negative plate 2 is electrically connected to the ground circuit of the ignition system.

Referring now to FIG. 2, the negative plate is shown generally at 2 and includes at least one flange 20 extending therefrom. During the molding process, the negative plate 2 is encased in the engineering polymer of the insulator 4, and the top end of the flange 20 is exposed so that the flange is in mechanical and electrical contact with the housing (not shown) of the spark plug, thereby ensuring that the plate 2 is in contact with the spark plug. The ground terminal of the ignition system is electrically connected. The scallops 21 of the flange 20 ensure that the engineering polymer of the insulator 4 flows completely around the plate 19 during the forming process so as to encase the plate 2 and place it concentrically with the ceramic cone 5 .

Preferably, the ceramic cone 5 has integral and concentric locking detents 27 into which the engineering polymer of the insulator 4 flows during the forming process, said detents 27 locking and setting the cone 5 relative to the negative plate 2 and with the negative electrode Plate 2 separates. In the ceramic cone 5 is formed a concentric cavity 26 which nests in the central or positive electrode 7 .

The central electrode 7 is provided with a boss 23, a stud 9 and an electrode tip 17 to prevent high-power discharge. The boss 23 of the center electrode 7 is inserted into the cavity 26 provided in the ceramic cone 5 . During manufacture, the cavity 26 is preferably filled with copper glass, ceramic epoxy or other suitable permanent sealing material at the top of the mounted center electrode 7 and boss 23 to provide a gas seal to protect the interior of the spark plug 1 from damage. The effect of combustion pressure. The stud 9 of the electrode 7 is provided to engage with an interference fit with the assembled capacitor positive plate (shown as 43 in Figure 4) to ensure completion of the positive terminal of the ignition circuit.

Referring now to FIG. 3, the center electrode 7 is provided with a corrosion resistant electrode tip 17, which is preferably made of a rhenium/tungsten alloy of about 50%-75% rhenium. One end of the corrosion-resistant electrode tip 17 is preferably flush with the end 30 of the ceramic cone 5 .

In the field of ignition or spark gap pulsed power supplies, it is well known that an increase in spark energy (watts) increases the corrosion rate of the electrodes, and that spark emitting electrodes corrode faster than receiving electrodes. Precious or precious metals such as gold, silver, platinum, and more recently iridium have been utilized in industry standards as optional electrode metals in order to reduce electrode corrosion for conventional ignition energies. But these metals are not enough to reduce the accelerated corrosion rate of electrodes under the high power discharge of the present invention. A .025"-.060" diameter, .100" length, preferably cylindrical configuration of sintered hybrid electrode tip 17 obtained by sintering approximately 50% to 75% by mass rhenium and tungsten, preferably by plasma, friction, or electron Beam welding methods, or other suitable methods capable of achieving durability while delivering a low resistance joint are attached to the center electrode 7.

The use of pure tungsten electrodes as a preferred corrosion-resistant material for electrodes in spark gap applications is well documented in the field of pulse-power supplies. However, when used in an internal combustion engine where the combustion temperature exceeds the oxidation temperature of tungsten, the electrodes are detrimentally corroded at a faster rate than noble metals. Tungsten can be used as an electrode material in automotive applications by insulating it from the oxygen present in the combustion chamber. This is achieved in part by sintering of tungsten with rhenium and a suitable binder such as, without limitation, a non-oxidic metal that has a lower melting temperature than rhenium and tungsten. The two preferred powdered base metals are mixed with the binder during sintering, and the binder is melted in the refractory treatment and the base material is sintered into the monolithic shape through the binder. This preferably rectangular shape is then pressed into a wire having a diameter of .025" to .060" to form electrode tips 17 and 45. The binder provides oxidation protection to the tungsten element by covering the portion of the tungsten that is not in contact with the rhenium.

While this provides some oxidation protection for the tungsten, the bond metal corrodes during high power electrical discharge machining and the raw tungsten at the electrode tips 17 and 45 is exposed to ambient oxygen in the combustion chamber, thereby accelerating the corrosion of the tungsten. However, the use of adhesives has greatly reduced the rate of corrosion due to exposure to oxygen. In addition, when tungsten corrodes, rhenium is now close to the opposite or negative electrode, and due to its proximity and field effect of the source of spark emission, rhenium, which is also highly resistant to high power corrosion, becomes the source of the spark flow.

In addition, by placing the electrode tip 17 relative to the ceramic cone 5, tungsten can be used as electrode material in automotive applications. In this placement, only the extreme end of the electrode tip 17 is exposed to the elements of the combustion chamber. The remainder of the cylindrical electrode tip 17 has been bonded to the ceramic cone 5, sealing the electrode tip 17 from any combustion gases including oxygen. In this way, only the extreme end of the electrode tip 17 will be corroded when subjected to the high power discharge conditions of the present invention.

As the electrode tip 17 wears away, the electrons of the ignition pulse will be emitted from the slotted electrode tip 17, ionize the ceramic cone wall 31, ionize at the spark gap (not shown) and generate a spark on the ground electrode 16 (not shown) Previous creeping onto the edge 30 of the ceramic cone 5 . The voltage required to ionize only the ceramic cone wall 31 above the corroded electrode tip 17 is so small that the total voltage required to cause the spark gap to break down and spark is much lower than to break down the pristine, uncorroded spark gap required voltage.

In this way, the electrode tip 17 can corrode to the point where the distance from the ground electrode 16 to the center or positive electrode tip 17 is doubled, and the voltage required to break down the doubled gap is slightly greater than the breakdown voltage of the original spark gap , and just below the effective voltage of the original equipment manufacturer's ignition system. This advantageously ensures proper engine operation for at least 10 ⁹ spark plug operations, or the equivalent of 100,000 miles.

Referring again to FIG. 3 , there is shown a formed composite insulator assembly indicated generally at 19 , the center electrode 7 with a corrosion resistant tip 17 , the ceramic cone 5 and the bonding and insulating engineering polymer 4 forming the assembly 19 . Referring now to the composite insulator 19 and center electrode 7 of FIG. 3, and the center conductor 43 of FIG. 43 to provide a highly conductive path between the ignition coil output (not shown) and the spark plug gap (not shown). Once connected to the center electrode 7, the center conductor 43 becomes the positive plate of the capacitive element, and the capacitor or capacitive element, indicated generally at 28 in FIG. The plates (plates 43 and 2 ) form a capacitor and the dielectric is an engineering polymer 4 .

The capacitance can be calculated by the formula;

$\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1.4122</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}<span\; class="notranslate">\; )</span>}$

where C is the capacitance per inch of the cylindrical plate, _Dc is the dielectric constant of the polymer 4, _Ln is the natural logarithm, _D is the inner diameter of the negative plate 2, and D _o is the positive plate in Fig. 4 43 OD. The capacitance can be increased by reducing the distance between the facing charge plates 43 and 2 or by increasing the surface area of the plates 43 and 2 . Capacitance can also be affected by the dielectric constant of the engineering polymer. Depending on the material chosen, the dielectric constant can vary from four to twelve.

Attention is now drawn to the central (or positive) electrode 7 of FIG. 3 and to the cavity 26 of the ceramic cone 5 in which the electrode 7 is embedded concentrically. Once the electrode 7 is inserted into the ceramic cone 5, a pressure or gas seal is achieved by completely filling the cavity 26 with ceramic epoxy, copper glass or other suitable high temperature sealant.

Referring now to FIG. 4 , the center conductor assembly, generally indicated at 33 , consists of tubular positive plate or conductor 43 , resistor 11 , conductive spring connector 10 , terminal insert 12 and high voltage cable or coil terminal 13 . Resistor 11 is inserted into cavity 41 of terminal insert 12 and is held in place during engine operation, preferably by a high temperature ceramic epoxy or other high temperature adhesive suitable for holding resistor 11 . The high voltage cable or coil terminal 13 is attached to the terminal insertion body 12 by screwing the threaded portion 48 of the terminal 13 into the cavity 40 of the terminal insertion body 12 . Once the terminal 13 is mounted by screwing into the terminal insertion body 12 , the pointing shaft 47 of the terminal 13 makes physical and electrical contact with the resistor 11 . The end of resistor 11 opposite terminal 13 is in physical and electrical contact with conductive spring 10 which is compressed when the center conductor assembly is inserted into composite insulator 19 of FIG. 3 .

The spring 10 opposite the end of the resistor 11 is in mechanical and electrical contact with the tubular positive plate or conductor 43, thus completing the forward circuit of the ignition pulse. Placing the resistor 11 in the forward circuit before the positive plate 43 of the capacitive element of the spark plug 1 allows the capacitor 28 to be discharged at a very high transfer efficiency ratio and the stored energy can be deposited at a large percentage greater than 95% as (deposit) to supply fuel. Normally, this hard deposit of energy would produce an abnormal amount of radio frequency or electromagnetic interference incompatible with the operation of the vehicle's engine control computer. Placing resistor 11 in the circuit before capacitor 28 allows this stacking while eliminating this interference.

FIG. 6 illustrates a typical electrical circuit 30 for the ignition device 1 of the present invention and shows a coil 35 (such as an ignition coil, etc.) connected to the resistor 11 via a secondary circuit 37 . Capacitor 28 is connected to resistor 11 in parallel with secondary circuit 37 and ground 34 . The resistor 11 advantageously suppresses the high-frequency electrical noise generated by the circuit 30 without affecting the high-power discharge of the capacitor 28 .

There are a large number of existing experiments with relevant results, see Society of Automotive Engineers paper 02FFFL-204 entitled "Automotive Ignition Transfer Efficiency", which focuses on the use of current peaking capacitors, e.g. with high voltage circuits such as ignition systems30 The use of capacitor 28 in parallel with 37 in order to improve the electrical transfer efficiency of the ignition, thereby coupling more electrical energy into the fuel supply. Achieves consistent ignition with respect to crank angle by coupling more electrical energy into the fuel supply, reducing cycle-to-cycle variations in peak combustion pressure and improving engine efficiency . An additional benefit of connecting the current peaking capacitor 28 in parallel is that a large solid flame core is created in the discharge of the capacitor 28 . The stronger core results in more compatible ignition and more complete combustion, which in turn leads to higher engine performance. One of the benefits of utilizing peaking capacitor 28 to improve engine performance is the ability to ignite fuel under extremely inclined conditions. Today's modern engines have introduced more and more exhaust gases into the intake of the engine in order to reduce emissions and improve fuel economy. The use of the peaking capacitor 28 will allow the automaker to skew the air:fuel ratio for additional exhaust levels beyond what the current car ignition is capable of.

Referring now to FIG. 5, there is shown a fully assembled composite insulator assembly, indicated generally at 6, consisting of an over-molded ceramic cone 5 and a center electrode 7 with a corrosion-resistant electrode tip 17. ) insulator 19, negative plate 2 of capacitive element 28 and insulating engineering polymer 4. Also shown is a cross-sectional view of the fully assembled element line of the center conductor assembly 33 shown in FIG. 10. The terminal insert body 12 and the high voltage cable or coil terminal 13 are composed. This view illustrates a fully assembled view of the composite insulator assembly 6 prior to being inserted and rolled into the spark plug housing 44 of FIG. 1 .

The gas seal and ground contact gasket 22 of FIG. 5 is placed in the housing 15 of FIG. 1 , which, by virtue of the transition in diameter, ensures that the negative plate 43 is in contact with the housing 15 and completes the grounding circuit of the capacitive element of the present invention.

An embodiment of the spark plug or ignition device 1 of the present invention provides a spark plug having insulators 4 and 5, wherein the insulators are a composite of heterogeneous materials. Embodiments of the spark plug or ignition device 1 include very small cross-sectional electrode tip 17 and 45 materials designed to effectively reduce corrosion of the electrode tips 17 and 45 throughout the high power discharge spark gap device. In an embodiment of the spark plug or ignition device 1, the insulator 4 is configured to create a capacitor 28 in parallel with the high voltage circuit 30 of the ignition system and to place an inductance or resistor 11 in the circuit 30 of the spark plug, wherein the resistor or inductance 11 is suitably shielded Any electromagnetic or radio frequency emission from a spark plug 1 that does not include a high power discharge of a spark. The embodiment of the spark plug or ignition device 1 also completes the capacitor 28 and the high voltage circuit 30 of the ignition system in order to provide a high power discharge path on the electrode 17 of the spark plug 1 .

Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can yield the same results. Variations and modifications to the present invention will be apparent to those skilled in the art, and the present invention is intended to cover all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above and/or in the appendices, as well as the corresponding applications, are hereby incorporated by reference.

Claims (48)

1. A compound ignition device for an internal combustion engine, comprising: a positive electrode bonded to the first insulator to form the ignition cone assembly, the positive electrode having an apex formed at an end thereof; a second insulator coupled to the ignition cone assembly, the second insulator including a negative capacitive element embedded therein; a positive capacitive element disposed within the second insulator and isolated from the negative capacitive element by the second insulator, the positive capacitive element connected to the positive electrode, the positive capacitive element connected to the said negative capacitive element forms a capacitor; a resistor disposed in a resistive insulator and connected to said positive capacitive element by a resistive connector; an electrical connector connected to said resistor and attached to said second insulator; and a housing attached to the second insulator and the ignition cone assembly and connected to the negative capacitive element, the housing including a negative electrode having formed thereon and connected to the The tops of the positive electrodes are spaced apart. 2. The apparatus of claim 1, wherein the second insulator is attached to the ignition cone assembly, and the negative capacitive element is embedded in the second insulator by injection molding. 3. The apparatus of claim 1, wherein the second insulator is attached to the ignition cone assembly, and the negative capacitive element is embedded in the second insulator by insert molding. 4. The device of claim 1, wherein the second insulator comprises an engineering polymer. 5. The device of claim 4, wherein the engineering polymer comprises a liquid crystal polymer. 6. The device of claim 4, wherein the engineering polymer comprises polyether ether ketone. 7. The device of claim 4, wherein the engineering polymer has a dielectric constant of from about 5 to about 10. 8. The apparatus of claim 1, wherein the first insulator comprises an alumina material. 9. The apparatus of claim 7, wherein the alumina material comprises from about 88% to about 99% pure alumina. 10. The apparatus of claim 1, wherein the resistive connector includes a spring member. 11. The device of claim 1 wherein said positive and negative electrode tips comprise rhenium and tungsten sintered material. 12. The device of claim 11, wherein the material is made of about 50% rhenium and about 50% tungsten. 13. The device of claim 11, wherein the material is made of about 75% rhenium and about 25% tungsten. 14. The device of claim 1, wherein the positive electrode further comprises a conductive ink coating on an outer surface thereof, the coating having a predetermined thickness. 15. The apparatus of claim 14, wherein the conductive ink comprises a noble metal or a noble metal alloy. 16. The apparatus of claim 1, wherein the capacitor has a predetermined capacitance in the range of from about 30 to about 100 picofarads. 17. The device of claim 1, wherein the positive capacitive element is connected to the positive electrode by an interference fit. 18. An electrical circuit for an ignition device of an internal combustion engine, comprising: operating a power source for intermittently activating said circuit; having a positive electrode at its tip; a ground electrode that is grounded and has at its end a tip spaced from the positive electrode tip by a predetermined spark gap; at least one resistor in series with said power source and said positive electrode; and At least one capacitor connected directly to the resistor in parallel with the positive electrode and ground. 19. The circuit of claim 18, wherein the at least one resistor reduces radio frequency interference (RFI) when the circuit is active. 20. The circuit of claim 18, wherein said at least one capacitor increases a peak current of said spark gap when said circuit is active. 21. The circuit of claim 18 wherein said positive and negative electrode tips comprise rhenium and tungsten sintered material. 22. The device of claim 22, wherein the material is made of about 50% rhenium and about 50% tungsten. 23. The device of claim 22, wherein the material is made of about 75% rhenium and about 25% tungsten. 24. The circuit of claim 18, wherein the resistor has a predetermined resistance value in the range of about 2 kiloohms to about 20 kiloohms. 25. The circuit of claim 18, wherein the capacitor has a predetermined capacitance in the range of about 30 to about 100 picofarads. 26. A method for forming a composite ignition device for an internal combustion engine comprising: bonding a positive electrode to a first insulator to form an ignition cone assembly, the positive electrode end portion including a tip formed thereon; embedding a negative capacitive element in a second insulator, and attaching the second insulator to the ignition cone assembly; connecting a positive capacitive element to said positive electrode in said second insulator, said positive capacitive element being isolated from said negative capacitive element by said second insulator, said positive capacitive element being connected to said The negative capacitive element forms a capacitor; setting the resistors in a resistive insulator; connecting said resistor to said positive capacitive element via a resistor connector; connecting an electrical connector to said resistor; connecting the electrical connector to the second insulator; attaching a housing to the second insulator and the ignition cone assembly, the housing including a negative electrode having a tip formed thereon, the negative electrode tip being spaced apart from the positive electrode tip; and The housing is connected to the negative capacitive element. 27. The method of claim 26, further comprising sealing the top of the electrode within the insulator. 28. The method of claim 26, further comprising coating the positive electrode with conductive ink prior to bonding the positive electrode to the first insulator. 29. The apparatus of claim 28, wherein the conductive ink comprises a noble metal or a noble metal alloy. 30. The method of claim 26, wherein said step of attaching said housing to said second insulator and said ignition cone assembly comprises folding said housing toward said first Two insulators and the ignition cone assembly. 31. The method of claim 26, wherein the step of connecting the housing to the negative capacitive element comprises folding the housing toward the negative capacitive element. 32. The method of claim 26, wherein said step of bonding said positive electrode to said first insulator comprises heating said positive electrode to said first insulator at a predetermined temperature for a predetermined time . 33. The method of claim 27, wherein the predetermined temperature is from about 750 degrees Celsius to about 900 degrees Celsius. 34. The method of claim 27, wherein the predetermined time is from about 10 minutes to about 60 minutes. 35. The method of claim 26, wherein said step of embedding a negative capacitive element in a second insulator and attaching said second insulator to said ignition cone assembly comprises injection molding. 36. The method of claim 26, wherein said step of embedding a negative capacitive element in a second insulator and attaching said second insulator to said ignition cone assembly comprises insert molding. 37. The method of claim 26, wherein the second insulator comprises an engineering polymer. 38. The method of claim 37, wherein the engineering polymer comprises a liquid crystal polymer. 39. The method of claim 37, wherein the engineering polymer comprises polyether ether ketone. 40. The method of claim 37, wherein the engineering polymer has a dielectric constant of from about 5 to about 10. 41. The method of claim 26, wherein the first insulator comprises an alumina material. 42. The apparatus of claim 41, wherein the alumina material comprises from about 88% to about 99% pure alumina. 43. The method of claim 26, wherein the resistive connector includes a spring member. 44. The method of claim 26, further comprising forming the positive and negative electrode tips by sintering rhenium and tungsten to form a sintered material. 45. The method of claim 44, wherein the material is made of about 50% rhenium and about 50% tungsten. 46. The method of claim 44, wherein the material is made of about 75% rhenium and about 25% tungsten. 47. The method of claim 26, wherein the capacitor has a predetermined capacitance in the range of about 30 to about 100 picofarads. 48. The method of claim 26, wherein said step of connecting a positive capacitive element to said positive electrode is accomplished by an interference fit.

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