EP1231687A2 - Zündkerze und damit ausgestattete Zündvorrichtung - Google Patents
Zündkerze und damit ausgestattete Zündvorrichtung Download PDFInfo
- Publication number
- EP1231687A2 EP1231687A2 EP02002968A EP02002968A EP1231687A2 EP 1231687 A2 EP1231687 A2 EP 1231687A2 EP 02002968 A EP02002968 A EP 02002968A EP 02002968 A EP02002968 A EP 02002968A EP 1231687 A2 EP1231687 A2 EP 1231687A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- center electrode
- protrusion
- electrode
- mounting bracket
- ignition
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T13/00—Sparking plugs
- H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T13/00—Sparking plugs
- H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
- H01T13/32—Sparking plugs characterised by features of the electrodes or insulation characterised by features of the earthed electrode
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T13/00—Sparking plugs
- H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
- H01T13/39—Selection of materials for electrodes
Definitions
- the present invention relates to a spark plug and an ignition apparatus using the same.
- FIG. 11 shows one type of conventionally used ordinary spark plug.
- This spark plug is provided with a mounting bracket 10, a cylindrical center electrode 30 mounted on the mounting bracket 10, and a prismatic earth electrode 40 fixedly coupled with the mounting bracket 10.
- the center electrode 30 has one end 31 formed into a cylinder and extends from one end 11 of the mounting bracket 10, the one end 31 being insulation-supported within the mounting bracket 10 from an insulating glass member 20 intervening therebetween.
- the earth electrode 40 has one end secured to the one end 11 of the mounting bracket 10 and the other end extends so that its frontal surface 43 faces the one end 31 of the center electrode 30.
- a high voltage generated by an ignition coil of an ignition power supply installed in an ignition apparatus is applied to a spatial gap (discharge gap) formed between the one end 31 of the center electrode 30 and the one surface 32 of the earth electrode 40.
- This application causes both the electrodes to ignite (i.e., spark discharge), thus firing an air-fuel mixture.
- an amount of input energy necessary for ignition is a sum of combustion energy necessary for firing the air-fuel mixture and cooling energy consumed by the electrodes of a spark plug.
- Japanese Patent Laid-open Publication No. 52-362237 discloses another way of improving the ignitability of a spark plug.
- both of a high-voltage electrode and an earth electrode are shaped into thin types of electrodes each protruding from each support member.
- the inventors conducted an abrasion test on an actual spark plug produced based on the concept of the protruding electrodes disclosed by the publication. The test results proved that the electrodes wore more badly than previously supposed by the inventors.
- the foregoing publication does not provide any information about how to reduce such poor wear performance.
- an object of the present invention is to provide, with due consideration to the drawback of such a conventional spark plug, a spark plug capable of lowering the ignition energy by regulating the conformations of the electrodes thereof, thus saving energy consumed by an ignition apparatus.
- a second object of the present invention is to provide a spark plug and an ignition apparatus using the same, which are able to secure a steady ignitability and reduce the wear of the electrodes.
- a first conclusion revealed by the inventors' study is that, when the one end of the center electrode and the protrusion of the earth electrode, which mutually faces with a discharge gap therebetween, are both a diameter-reduced cylindrical shape of which diameter is 2.3 [mm] or less, energy necessary for ignition can be lowered down to amounts of 17 [mJ] or less.
- a first configuration of the present invention is an ignition apparatus having a spark plug comprising: a mounting bracket (10) capable of being mounted to an internal combustion engine; a center electrode (30) insulatedly-supported by the mounting bracket, one end (31) of which being a cylindrical form and exposedly extending from one end (11) of the mounting bracket; and an earth electrode (40) having one end coupled with the one end of the mounting bracket and the other end on which one surface (43) is formed to face to the one end of the center electrode, the one surface having a cylindrical protrusion (41) being secured thereon and extending toward the center electrode so as to face the one end of the center electrode, a spacing formed between the one end of the center electrode and the protrusion of the earth electrode serving as a discharge gap (50), the one end of the center electrode and the protrusion of the earth electrode being both 2.3 [mm] or less, and an amount of ignition energy required by the spark plug being less than 17 [mJ].
- the shapes of the electrodes of the spark plug are regulated to lower energy for the ignition, so that the ignition apparatus of which consumed power is saved can be provided.
- a second configuration of an ignition apparatus in which a feature is such that a spacing formed between the one end (31) of the center electrode (30) and the protrusion (41) of the earth electrode (40) serves as a discharge gap (50), the one end of the center electrode and the protrusion of the earth electrode being both 2.3 [mm] or less, and a density of ignition energy required by the spark plug being less than 32 [W].
- the ignition apparatus of which consumed power is saved can be provided.
- the inventors' study also included an examination of distances of a discharge gap to give a steady ignitability, by using a spark plug of which one end of a center electrode and a protrusion of an earth electrode are both reduced in diameter down to 2.3 [mm] or less.
- the result showed a second conclusion that, even when the discharge gap is 0.6 [mm] or less in length, such diameter-reduced electrodes still provide a good and steady ignitability.
- the third conclusion and tolerances for discharge gaps (approximately 0.1 mm in a gap width) in manufacturing spark plugs are both considered.
- Both of the one end of the center electrode and the protrusion of the earth electrode are shaped into cylindrical forms of which diameters are each reduced to 2.3 [mm] or less, and the discharge gap being 0.7 [mm] or less in length.
- Narrowing the discharge gap down to 0.7 [mm] or less reduces requested voltage, which allows the withstand voltage of the spark plug to be lowered. A more compact spark plug can be available.
- a thread diameter of the threaded part is M12 or less.
- the threaded part can therefore be made compact, still providing a sufficient withstand voltage to the spark plug.
- the foregoing reduction of the diameters of the electrodes to 2.3 [mm] or less may be effective in lowering ignition energy.
- a sufficient advantage in lowing the ignition energy depends on the length (protruding length) of the protrusion (diameter-reduced part) of the earth electrode.
- an excessively small protruding length may become an obstacle to the growth of a flame nucleus, failing to sufficiently provide the advantages thanks to the diameter-reduced electrodes.
- the protruding length is too large, the heat drawability may be deteriorated at the earth electrode, thereby lowering the heat resistance of the protrusion of the earth electrode.
- the inventors also performed a study for obtaining the relationship between the protruding length of the protrusion and necessary ignition energy, and gained a fourth conclusion reflected in a fifth configuration.
- a fifth configuration is directed to a spacing formed between the one end (31) of the center electrode (30) and the protrusion (41) of the earth electrode (40) serving as a discharge gap (50).
- Both of the one end of the center electrode and the protrusion of the earth electrode are 2.3 [mm] or less, and a protruding length (L) of the protrusion is 0.3 [mm] or more.
- the protruding length (L) can be 1.5 [mm] or less. This not only prevents the heat drawability from being deteriorated but also secures an enough heat resistance at the earth electrode.
- the one end (31) of the center electrode (30) and the protrusion (41) of the earth electrode (40) are both 1.1 mm or less in diameter. This provides a further reduction in the diameter of each of the electrodes. By this reduction, energy necessary for ignition can be lessened greatly compared to that needed for the conventional spark plug.
- an ignition apparatus comprises the spark plug (S1) of the third configuration; and an ignition power supply (60) for applying voltage to the center electrode (30) and the earth electrode (41). Regulating the conformations of the electrodes makes it possible to provide the ignition apparatus of which consumed power is saved.
- an ignition apparatus comprises the ignition plug (S1) of the third embodiment; and n ignition power supply (60) having an ignition coil for applying voltage to the center electrode (30) and the earth electrode (41), the ignition coil being 22 [mm] or less in coil diameter.
- the ignition coil can be made more compact.
- a spacing is formed between the one end (31) of the center electrode (30) and the protrusion (41) of the earth electrode (40) serving as a discharge gap (50).
- the one end of the center electrode and the protrusion of the earth electrode are both 2.3 [mm] or less, and the protrusion is made of one selected from a group consisting of a platinum-based alloy and an iridium-based alloy.
- a positive voltage is applied to the center electrode by the ignition power supply when starting the discharge.
- the earth electrode is easier to wear.
- adopting the tenth configuration in which a platinum-based alloy or an iridium-based alloy is used to make the protrusion at the earth electrode prevents such a drawback. That is, the wear of the protrusion can be suppressed with the ignition apparatus still power-saved.
- an eleventh configuration is obtained from the ignition apparatus of the first configuration. Specifically, it is preferred that both of the one end (31) of the center electrode (30) and the protrusion (41) of the earth electrode (40) are 1.1 [mm] or less in diameter.
- the shapes of both the one end of the center electrode and the protrusion of the earth electrode are not limited to cylindrical forms. Any pillar form, such as a prismatic form or a pillar form with a step(s), may be used. Even in such a pillar shape, as long as both of the one end of the center electrode and the protrusion of the earth electrode maintain a sectional areas of 4.2 [mm 2 ] or less at all points perpendicular to each axial direction, the similar advantages to the cylindrical one of which diameter is reduced down to 2.3 [mm] or less can be provided.
- a twenty-third configuration of the present invention has a feature that an ignition energy E [mJ] is applied to the spark plug so that an ignition occurs between the center and earth electrodes, a diameter D of the protrusion is 0.4 [mm] or more, but 2.3 [mm] or less, and relationships of 0.3[mm] ⁇ L ⁇ 0.016E 2 -0.56E+5.2[mm] in which 8.5[mJ] ⁇ E ⁇ 17[mJ] are realized between a length L of the protrusion and the ignition energy E [mJ]. Because 8.5[mJ] ⁇ E is maintained, a steady ignitability is given, while E ⁇ 17[mJ] is maintained, necessary ignition energy is reduced to an amount smaller than that required by the conventionally used ordinary spark plug. Thus, the ignition energy can be saved.
- the protruding length L is determined so that L ⁇ 0.016E 2 -0.56E+5.2 [mm] is kept, the tip of the earth electrode will be cooled moderately, thereby reducing the wear of the electrodes.
- the excellent ignitability is obtained, the ignition energy can be reduced more, and the wear of the electrodes can be lessened because the ignition energy will not deteriorate the cooling performance of the earth electrode.
- both of the one end of the center electrode and the protrusion of earth electrode are 4.2 [mm 2 ] or less in sectional area and a density of the ignition energy is 32 [W] or less. Hence the energy required for ignition can be saved.
- both of a diameter D1 of the one end of the center electrode and a diameter D2 of the protrusion of earth electrode are 2.3 [mm] or less and a relationship of 1.5D2 2 +0.1D2+8 [mJ] ⁇ E ⁇ 0.34D1 2 +0.2D1+16.4[mJ] between the ignition energy E [mJ] and the diameters D1 and D2 is realized.
- a relationship of 1.5D2 2 +0.1D2+8 [mJ] ⁇ E ⁇ 0.34D1 2 +0.2D1+16.4[mJ] between the ignition energy E [mJ] and the diameters D1 and D2 is realized.
- both of a diameter D1 of the one end of the center electrode and a diameter D2 of the protrusion of the earth electrode are 2.3 [mm] or less and a relationship of 3D2 2 +0.2D2+16[W] ⁇ Q ⁇ 0.68D1 2 +0.4D1+32.8 [W] between the density of the ignition energy Q [W] and the diameters D1 and D2 is realized.
- the same advantages as the twenty-fifth configuration can be obtained.
- a discharge (50) formed between the one end and the protrusion is 0.7 [mm] or less in distance.
- a steady ignitability is secured, while still lowering voltage required by a spark plug.
- the withstand voltage of the spark plug can also be lowered, thereby making the spark plug more compact.
- a thread diameter of the threaded part may be M12 or less.
- a sufficient value of withstand voltage of a spark plug can be given.
- the protruding length L of the protrusion on the earth electrode is 1.5 [mm] or less. This makes it possible to avoid heat drawability at the electrode from being deteriorated, thus securing a higher heat resistance of the protrusion, thus improving wear resistance.
- the protruding length L is 0.8 [mm] or less, moderately suppressing a deterioration in the heat drawability, thus improving wear resistance.
- both of the one end (31) of the center electrode (30) and the protrusion (41) of the earth electrode (40) are 1 [mm 2 ] or less in a sectional area. This enables a further reduction of the diameter, energy necessary for ignition can be lowered to an amount smaller than the conventional by a considerable amount of energy.
- an ignition power supply (60) has an ignition coil for applying voltage to the center electrode (30) and the earth electrode (41) and the ignition coil is 22 [mm] or less in coil diameter, voltage required by the ignition coil can be lowered. Though the ignition coil is smaller in diameter, its required inner withstand voltage can be reduced, making its production easier.
- both of the one end (31) of the center electrode (30) and the protrusion (41) of the earth electrode (40) are 1 [mm 2 ] or less in a sectional area. This enables a further reduction of the diameter, energy necessary for ignition can be lowered to an amount smaller than the conventional by a considerable amount of energy.
- the protrusion (41) of the earth electrode (40) is made of an alloy of which main composition is Pt and to which at least one component selected from the group consisting of Ir, Ni, Rh, W, Pd, Ru and Os is added. This makes it possible to reduce the wear at the protrusion.
- the protrusion (41) of the earth electrode (40) is made of an alloy of which main composition is Pt and to which at least one component selected from the group consisting of Ir of 0 to 50 wt%, Ni of 0 to 40 wt%, Rh of 0 to 50 wt%, W of 0 to 30 wt%, Pd of 0 to 40 wt%, Ru of 0 to 30 wt%, and Os of 0 to 20 wt% is added.
- the wear that will occur at the protrusion can be weakened.
- the protrusion (41) of the earth electrode (40) is made of an alloy of which main composition is Ir and to which at least one component selected from the group consisting of Rh, Pt, Ni, W, Pd, Ru and Os is added.
- the wear that will occur at the protrusion can also be weakened.
- the protrusion (41) of the earth electrode (40) is made of an alloy of which main composition is Ir and to which at least one component selected from the group consisting of Rh of 0 to 50 wt%, Pt of 0 to 50 wt%, Ni of 0 to 40 wt%, W of 0 to 30 wt%, Pd of 0 to 40 wt%, Ru of 0 to 30 wt%, and Os of 0 to 20 wt% is added.
- the wear at the protrusion can be lessened.
- FIG. 1 partially shows the configuration of a spark plug S1, but only an essential part thereof, according to the first embodiment.
- the spark plug S1 has a mounting bracket 10, which can be attached to an automobile engine (not shown) employed as an internal combustion engine.
- the mounting bracket 10 is made of carbon steel and manufactured into a cylindrical form through various types of working, such as cold forging and cutting working.
- Fig. 1 shows one end of the mounting bracket 10.
- a mounting threaded part 12 for thread-fastening the spark plug to a mounting hole of the engine.
- the thread diameter of the mounting threaded part 12 can be formed as being a size of M12 or less.
- a center electrode 30 is incorporated with an insulator (insulating glass member) made of an electrically insulating material such as alumina. This allows the center electrode 30 to be supported by the mounting bracket 10 in an electrically insulated manner.
- the center electrode 30 is formed into a rod and attached to the mounting bracket 10 so that it extends along the axial direction of the spark plug S1. Further, one end 31 of the center electrode 30 protrudes from one end 11 of the mounting bracket 10 so as to be exposed in the air.
- the one end 31 of the center electrode 30 is a tip made of a platinum-based alloy or an iridium-based alloy weld-fastened on a base 32 made of nickel-based alloy.
- the base 32 is made to taper little by little toward the one end 31 (tip) of the center electrode 30.
- the tip 31 is shaped into a cylinder extending by a predetermined length from the base 32 along the axial direction of the spark plug S1.
- an earth electrode 40 having a base 42 and a cylindrical protrusion 41 extending from the base 42.
- the base 42 of which one end is secured to the mounting bracket 10, extends from the one end 11 thereof, and then bends almost perpendicularly so that one frontal surface 43 of the other end thereof faces to the tip 31 of the center electrode 30.
- the protrusion 41 is fixedly built on the one surface 43 of base 42 in such a manner that it approaches and faces to the tip 31 of the center electrode 30.
- the base 42 of the earth electrode 40 is shaped into a prismatic form.
- a part of the earth electrode 40 ranging from one end to a predetermined position in the course thereof extends along the axial direction of the center electrode 30 (i.e., the axial direction of the plug).
- the remaining part is bent approximately perpendicularly so that its tip is located over the tip 31 of the center electrode 30.
- Both of the tip 31 of the center electrode 30 and the protrusion 41 of the earth electrode 40 are made to be coaxial with each other.
- the base 42 of the earth electrode 40 is made of a material such as a nickel-based alloy, and its protrusion 41 is composed of a tip made of a platinum-based alloy or an iridium-based alloy fastened on the base 42 by means of welding.
- An opposing spacing is left, as a discharge gap 50, between the frontal surface of the tip 31 of the center electrode 30 and the frontal surface of the protrusion 41 of the earth electrode 40, both of the tip 31 and the protrusion 41 being cylindrical.
- the ignition apparatus has the foregoing ignition plug S1 and an ignition power supply 60 for applying voltage to the center and earth electrodes 30 and 40 of the spark plug S1.
- the ignition power supply 60 includes a stick type of ignition coil (not shown) to generate a high voltage and is configured to apply the negative potential of the voltage to the center electrode 30.
- the dimensions of the constituents are characteristic of regulated amounts as follows.
- the diameter D1 of the tip 31 of the center electrode 30 and the diameter D2 of the protrusion 41 of the earth electrode 40 are both 2.3 [mm] or less (preferably, 1.1 [mm] or less).
- the discharge gap 50 is preferably 0.7 [mm] or less.
- the protruding length L of the protrusion 41 of the earth electrode 40 is 0.3 [mm] or more.
- the foregoing ignition coil is 22 [mm] or less in diameter.
- Fig. 3 shows analyzed results of the relationship between the diameter of the center electrode and an amount of input energy necessary for ignition (necessary input energy) .
- data shown by "comparative example” were obtained from the conventional ordinary spark plug produced as shown in Fig. 11 (i.e., a discharge part of the earth electrode 40 is 1.6 [mm] in width and 2.8 [mm] in thickness) .
- Each sample was attached to an engine, and a density of ignition energy necessarily inputted and an amount of necessary input energy were acquired sample by sample, under the operational conditions that a pressure in the engine when igniting is 0.5 [Mpa], A/F (a mixture ratio of air to fuel) is 22, a density of oxygen of air injected is 18 [%], and a flow velocity of air-fuel mixture when igniting is 5 [m/s]. These operational conditions provide the highest amount of necessary inputted energy in practical use.
- the density of ignition energy necessarily inputted was calculated as a multiplication of current and voltage of a spark plug under discharge.
- the necessary inputted energy is then obtained by multiplying the necessary inputted energy density by a discharge time of 0.5 [ms] necessary under the foregoing operational conditions.
- the lateral axis shows the diameter D1 [mm] of the tip 31 of the center electrode 30.
- the left longitudinal axis shows the necessary input energy [mJ] and the right longitudinal axis shows the necessary inputted energy density [W].
- the spark plug according to the embodiment (filled circles), in which both the tip 31 of the center electrode 30 and the protrusion 41 of the earth electrode 40 are 2.3 [mm] or less in diameter, is able to lower the cooling energy consumed by the electrodes. That is, the necessary input energy can be reduced down to amounts of less than 17 [mJ], and the necessary input energy density can be lowered down to amounts of less than 32 [W].
- the necessary input energy (and its density) in relation to the diameter of the tip of the center electrode can be set an amount selected from the range between the two definitions stated above. Such setting enables the spark plug to have a satisfactory ignitability with an amount of ignition energy smaller than that required for the spark plug according to the comparative example.
- regulating the diameters D1 and D2 of the discharge parts 31 and 41 of both the electrodes 30 and 40 to amounts of 2.3 [mm] or less enables ignition energy (ignition energy density) to be lessened compared to 17 [mJ] (32 [W]) required for the conventional spark plug. This saves energy consumed by the ignition apparatus.
- Fig. 4 exhibits analyzed results of the relationship between various lengths of the discharge gap (plug gap) and ignitability.
- a lean limit is used as a factor indicative of the ignitability.
- the lean limit is defined as an A/F with the least fuel, which still satisfies a combustion fluctuation rate PmiCOV ("dispersion of mean effective pressure"/"mean value") at which combustion is established without fail.
- Curves rebelled as the "Comparative example” in Fig. 4 were derived from the conventional ordinary spark plug having the structure shown in Fig. 11, of which earth electrode 40 has, as describe above, a discharge part shaped in 1.6 [mm] in width and 2.8 [mm] in thickness.
- Various spark plug samples were manufactured with center electrode 30 changed into 0.4 [mm], 1.1 [mm], and 2.5 [mm] in the diameter D1 of the one end 31, respectively.
- Each sample was attached to a four-cylinder, 1800 [cc] engine and, under an idling state (800 [rpm] and a water temperature of 50 [°C]) that imposes a hard combustion condition (firing condition) on the engine, the lean limit to satisfy a combustion fluctuation rate PmiCOV of 15 [%] was obtained.
- the lateral axis shows the discharge gap (plug gap: [mm]), while the longitudinal axis shows the lean limit (A/F).
- the curves rebelled as the comparative example indicating conventional spark plugs (represented by the filled circles), even when the diameter of the protruding part of the center electrode 30 is made smaller down to 1.1 [mm] or less, there is no difference in improvement of the ignitability in the range of discharge gaps of 0.8 [mm] or more.
- the ignitability is lowered when the discharge gap is made smaller than 0.8 [mm], despite degrees at which the one end 31 of the center electrode is made thinner in diameter. The reason is considered such that a quench action (an obstacle to the growth of a flame nucleus) resultant from the earth electrode 40 has a large influence on the ignitability.
- the ignitability can be improved largely compared to the conventional ones in cases where the discharge gap is 0.6 [mm] or more.
- the necessary inputted energy is also decreased from "40 [W] x 0.4 [ms],” which is an amount corresponding to the conventional, to "20 [W] x 0.4 [ms]."
- the required voltage is lowered when the discharge gap is 0.7 [mm] or less, and the withstand voltage needed for a spark plug can be lowered as well. It is therefore possible to make the spark plug compact.
- the threaded part 12 for thread-coupling with an engine is formed on the outer circumferential surface of the mounting bracket, as explained before, the thread part 12 can be made compact in its thread diameter.
- Fig. 5 represents the relationship between the discharge gap (plug gap: [mm]) and the required voltage [kV], which was also studied by the inventors.
- Fig. 6 represents the relationship between the thread diameter of the threaded part 12 and the withstand voltage [kV] of the spark plug.
- Fig. 8 also exhibits analyzed results conducted by the inventors, which is directed to the relationship between the protruding length L of the protrusion 41 of the earth electrode 40 and the necessary input energy.
- Each sample was attached to an engine and subjected to the following operational conditions to obtain amounts of necessary input energy.
- the conditions were determined such that a pressure in the engine when staring the ignition was 0.5 [Mpa], A/F was 22, a density of oxygen of injected air was 18 [%], and a flow velocity of air-fuel mixture when starting the ignition is 1 [m/s].
- the lateral axis of Fig. 8 represents the earth electrode protruding length L [mm], whilst the longitudinal axes thereof represents the necessary input energy [mJ].
- a spark plug of which length L is zero corresponds to the conventional one.
- the graphs show that, in cases where the earth electrode protruding length L is 0.3 [mm] or more, the inputted ignition energy can be reduced largely, compared to the conventional, with no relation to the dimensions of the discharge gap 50.
- This advantage is derived from the fact that the base 42 of the earth electrode 40 can be far away from a flame nucleus so as not to influence its growth.
- the earth electrode protruding length L is 0.3 [mm] or more, the cooling energy can be lowered, thus providing a steady ignition energy lowering effect thanks to the foregoing thinning of the electrode discharge parts. Therefore, the ignitability can be improved.
- the length L of the protrusion 41 of the earth electrode 40 is too long, it may be difficult to give a high heat resistance to the protrusion 41, due to a deterioration in the heat drawability thereof. Hence, it is desirable that the length L of the protrusion 41 remain within amounts of 1.5 [mm] or less.
- Figs. 12 and 13 show analysis results conducted by the inventors in relation to the wear of the spark plug of which electrodes have protruding parts formed according to the present embodiment.
- the lateral axis shows the protruding length of the protrusion on the earth electrode, while the longitudinal axis shows a wearout rate.
- the wearout rate shows amounts worn off by the spark plug according to the present embodiment, and is indicated by making comparison with a conventional spark plug of which center electrode has a protruded part alone, as shown in Fig. 11.
- each protrusion (or protrude part) of both the conventional spark plug and the plug and according to the present embodiment was 0.4 [mm] in diameter.
- the protruded tip part of center electrode of the conventional spark plug and both the protruded tip of the center electrode and the protrusion of the earth electrode of the spark plug according to the present embodiment were made of the same material, that is, iridium including of 10 wt% rhodium.
- the amounts of wear were measured as gap lengths.
- the test used a 2000 [cc] engine with a supercharger operated at an rotation speed of 5600 [rpm] for 200 hours, with an air fuel ratio (A/F) of 12.5 and a fully opened throttle.
- a first line connecting the filled triangles indicates wearout rates obtained when ignition energy of which density is 40 [W] was applied for 0.4 [ms], while a second line connecting the filled circles wearout rates obtained when ignition energy of which density is 20 [W] was applied for 0.4 [ms].
- the line connecting the filled circles shows a comparatively gentle increasing slope with an increase in the protruding length.
- the line connecting the filled triangles shows a comparatively sharp increase at a protruding length of approximately 0.5 [mm] with an increase in the protruding length.
- the electrode is reluctant to be cooled and the temperature at the tip of the protrusion (or protruding part) increases, so that the wear thereat becomes larger.
- the line connecting the filled circles reveals that, as long as an ignition energy density of approximately 20 [W] is applied for some 0.4 [ms] and the protruding length remains within 1.6 [mm] or less, a wearout ratio equivalent to the conventional can be secured. That is, Fig. 12 suggests that the wearout ratio equivalent to the conventional can be obtained by selecting a condition (ignition energy to be applied) from the range defined by both the conditions (applied ignition energy) assigned to the two curves.
- Fig. 13 shows an equi-wearout rate line connecting coordinates of ignition energy and protruding lengths, both of which satisfy a ware-out rate of 1.
- the lateral axis represents the ignition energy E and the longitudinal axis represents the protruding length L.
- L 0.016E 2 -0.56E+5.2
- the foregoing embodiment is also able to provide the ignition power supply 60 that has the identical various advantages to those ones.
- the ignition power supply that is able to save power energy can be provided.
- the spark pug S1 has the tip 31 of the center electrode 31 and the protrusion 41 of the earth electrode 40 are both reduced in diameter down to 2.3 [mm] and made of a noble metal such as a platinum-based alloy or an iridium-based alloy.
- the ignition apparatus 60 which is electrically coupled to such spark plug S1 as shown in Fig.2, is configured to apply voltage such that the center electrode 30 is subjected to its negative (-) potential.
- the voltage created by the ignition apparatus can be applied such that the center electrode 30 receives it positive (+) potential.
- the alternating-current voltage can also be applied in the same way.
- the protrusion 41 of the earth electrode 40 be made of a platinum-based alloy or an iridium-based alloy.
- the center electrode 30 In cases where the center electrode 30 is subjected to receive the positive (+) potential of the voltage, the discharge will occur such that electrons impinge onto the tip 31 of the center electrode 30 and positive ions impinge onto the protrusion 41 of the earth electrode 40. Because, the positive ion is higher in mass than the electron, the protrusion 41, onto which the positive ions impinge, is apt to wear more than the tip 31 of the center electrode 30.
- the above modification is able to provide the protrusion 41 made of a platinum-based alloy or an iridium-based alloy that shows higher heat resistance and higher wear resistance, so that the wear can be suppressed moderately.
- the protrusion 41 of the earth electrode 40 is made of an alloy of which main composition is Pt and to which at least one component selected from the group consisting of 0 to 50 wt% of Ir, 0 to 40 wt% of Ni, 0 to 50 wt% of Rh, 0 to 30 wt% of W, 0 to 40 wt% of Pd, 0 to 30 wt% of Ru, and 0 to 20 wt% of Os is added.
- the protrusion 41 of the earth electrode 40 may be made of an alloy of which main composition is Ir and to which at least one component selected from the group consisting of 0 to 50 wt% of Rh, 0 to 50 wt% of Pt, 0 to 40 wt% of Ni, 0 to 30 wt% of W, 0 to 40 wt% of Pd, 0 to 30 wt% of Ru, and 0 to 20 wt% of Os is added.
- FIGs. 9A and 9B Various embodiments with respect to the positional relationship between the center electrode 30 and the earth electrode 40 are shown in Figs. 9A and 9B.
- Both the center electrode 30 and the earth electrode 40 can be arranged in such a manner that the axial directions of the tip 31 and the protrusion 41 cross to each other at a certain angle, as shown in Fig. 9A or 9B.
- the frontal surface of the protrusion 40 of the earth electrode faces to a side of the tip 31 of the center electrode 30.
- the tip 31 and the protrusion 41 of both the electrodes 30 and 40 may be made of materials other than the foregoing ones. Such materials include the same material as that composing their bases 32 and 42, such as a Ni-based alloy. When such materials are used, the tip 31 and the protrusion 41 can therefore be formed by cutting each base or welding a thin-diameter chip.
- both of the tip 31 of the center electrode 30 and the protrusion 41 of the earth electrode 40 may be produced into various shapes, not limited to a cylindrical shape described above.
- Either the tip 31 or the protrusion 41 or both of them may be produced into a prismatic shape, pillar shape with a step (s), or pillar shape with an arbitrary cross section.
- Various shapes of both the tip 31 and the protrusion 41 are exemplified in Figs. 10A to 10G.
- Figs. 10A and 10B exemplify a prismatic shape and a pillar with a step, respectively.
- Fig. 10C shows one example of a pillar shape of which cross-section perpendicular to its axis is tapered.
- Fig. 10D shows a hollow cylinder, while Fig. 10E shows its cross section perpendicular to its axis.
- Fig. 10F shows a prismatic pillar with a groove on its one side, while Fig. 10G shows its cross section perpendicular to its axis.
- Each pillar depicted in Figs. 10A to 10G is limited to an amount of 4.2 [mm 2 ] or less in the sectional area perpendicular to each axis. That is, every section (i.e., other than the hollow portion or the groove potion shown in Fig. 10E or 10G) perpendicular to the axis of each pillar is 4.2 [mm 2 ] or less in its sectional area.
- a power-saving type of ignition apparatus is provided with a spark plug of which electrodes (30, 40) are regulated in their shapes to lower an amount of energy required for its ignition.
- a cylindrical protrusion (41) is built on one surface (43) of an earth electrode (40). The protrusion extends toward the center electrode to form a discharge gap (50) between the protrusion and the tip of the center electrode.
- Both of the tip of the center electrode and the protrusion of the earth electrode are 2.3 [mm] or less in each diameter (D1, D2), thus an amount of energy required for ignition being limited to 17 [mJ] or less.
Landscapes
- Spark Plugs (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2001035932 | 2001-02-13 | ||
JP2001035932 | 2001-02-13 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP1231687A2 true EP1231687A2 (de) | 2002-08-14 |
EP1231687A3 EP1231687A3 (de) | 2008-03-19 |
EP1231687B1 EP1231687B1 (de) | 2012-11-07 |
Family
ID=18899295
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP20020002968 Expired - Lifetime EP1231687B1 (de) | 2001-02-13 | 2002-02-11 | Zündkerze und damit ausgestattete Zündvorrichtung |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP1231687B1 (de) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004107517A1 (ja) | 2003-05-28 | 2004-12-09 | Ngk Spark Plug Co., Ltd. | スパークプラグ |
DE102006000151B4 (de) * | 2005-04-01 | 2017-12-07 | Denso Corporation | Zündkerze mit Masseelektrodenvorsprungelement mit inneren und äusseren Rändern |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04209968A (ja) | 1990-12-06 | 1992-07-31 | Ngk Spark Plug Co Ltd | 内燃機関の点火装置 |
EP0989646A1 (de) | 1998-09-22 | 2000-03-29 | NGK Spark Plug Co. Ltd. | Zündkerze und Zündanordnung zur Anwendung in einem Verbrennungsmotor |
EP1001502A2 (de) | 1998-11-09 | 2000-05-17 | Ngk Spark Plug Co., Ltd | Zündsystem |
EP1026394A2 (de) | 1999-02-08 | 2000-08-09 | Hitachi, Ltd. | Zündspule für Brennkraftmaschine |
US6147441A (en) | 1995-12-06 | 2000-11-14 | Denso Corporation | Spark plug |
-
2002
- 2002-02-11 EP EP20020002968 patent/EP1231687B1/de not_active Expired - Lifetime
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04209968A (ja) | 1990-12-06 | 1992-07-31 | Ngk Spark Plug Co Ltd | 内燃機関の点火装置 |
US6147441A (en) | 1995-12-06 | 2000-11-14 | Denso Corporation | Spark plug |
EP0989646A1 (de) | 1998-09-22 | 2000-03-29 | NGK Spark Plug Co. Ltd. | Zündkerze und Zündanordnung zur Anwendung in einem Verbrennungsmotor |
EP1001502A2 (de) | 1998-11-09 | 2000-05-17 | Ngk Spark Plug Co., Ltd | Zündsystem |
EP1026394A2 (de) | 1999-02-08 | 2000-08-09 | Hitachi, Ltd. | Zündspule für Brennkraftmaschine |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004107517A1 (ja) | 2003-05-28 | 2004-12-09 | Ngk Spark Plug Co., Ltd. | スパークプラグ |
EP1628375A1 (de) * | 2003-05-28 | 2006-02-22 | Ngk Spark Plug Co., Ltd. | Zündkerze |
EP1628375A4 (de) * | 2003-05-28 | 2007-08-01 | Ngk Spark Plug Co | Zündkerze |
US7279827B2 (en) | 2003-05-28 | 2007-10-09 | Ngk Spark Plug Co., Ltd. | Spark plug with electrode including precious metal |
EP2197077A3 (de) * | 2003-05-28 | 2015-07-15 | NGK Spark Plug Co., Ltd. | Edelmetallelement |
DE102006000151B4 (de) * | 2005-04-01 | 2017-12-07 | Denso Corporation | Zündkerze mit Masseelektrodenvorsprungelement mit inneren und äusseren Rändern |
Also Published As
Publication number | Publication date |
---|---|
EP1231687B1 (de) | 2012-11-07 |
EP1231687A3 (de) | 2008-03-19 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US7267116B2 (en) | Spark plug and ignition apparatus using same | |
US6229253B1 (en) | Spark plug with specific gap between insulator and electrodes | |
US7714489B2 (en) | Spark plug including ground electrode with arcuately curved face | |
US7615915B2 (en) | Spark plug | |
US5581145A (en) | Spark plug | |
US20040140745A1 (en) | Spark plug | |
US20070188065A1 (en) | Spark plug for internal combustion engine | |
JPH0750192A (ja) | ガスエンジン用スパークプラグ | |
JP4270784B2 (ja) | スパークプラグ | |
JP2020194762A (ja) | 点火プラグ | |
US7230370B2 (en) | Spark plug | |
JPH11121142A (ja) | 多極スパークプラグ | |
US7145287B2 (en) | Spark plug having noble metal tip | |
EP0535584B1 (de) | Zündkerze und sein Herstellungsverfahren | |
JPH05326107A (ja) | スパークプラグ | |
US4439708A (en) | Spark plug having dual gaps | |
JP4100725B2 (ja) | 内燃機関用スパークプラグ | |
US5502352A (en) | Spark plug having horizontal discharge | |
JP2006120649A (ja) | スパークプラグ及びそれを用いた点火装置 | |
EP1231687A2 (de) | Zündkerze und damit ausgestattete Zündvorrichtung | |
US6455988B1 (en) | Spark plug having a particular resistor | |
JP2902186B2 (ja) | 気体燃料機関用スパークプラグ | |
US5196760A (en) | Spark plug for internal combustion engine with pillar shaped electrode | |
JP2725261B2 (ja) | 内燃機関用スパークプラグ | |
JP5783927B2 (ja) | スパークプラグ |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A2 Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR |
|
AX | Request for extension of the european patent |
Free format text: AL;LT;LV;MK;RO;SI |
|
PUAL | Search report despatched |
Free format text: ORIGINAL CODE: 0009013 |
|
AK | Designated contracting states |
Kind code of ref document: A3 Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR |
|
AX | Request for extension of the european patent |
Extension state: AL LT LV MK RO SI |
|
17P | Request for examination filed |
Effective date: 20080610 |
|
AKX | Designation fees paid |
Designated state(s): DE FR GB |
|
17Q | First examination report despatched |
Effective date: 20090203 |
|
TPAC | Observations by third parties |
Free format text: ORIGINAL CODE: EPIDOSNTIPA |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R079 Ref document number: 60243988 Country of ref document: DE Free format text: PREVIOUS MAIN CLASS: H01T0001220000 Ipc: H01T0013200000 |
|
RIC1 | Information provided on ipc code assigned before grant |
Ipc: H01T 13/39 20060101ALI20120306BHEP Ipc: H01T 13/32 20060101ALI20120306BHEP Ipc: H01T 13/20 20060101AFI20120306BHEP |
|
GRAP | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOSNIGR1 |
|
GRAC | Information related to communication of intention to grant a patent modified |
Free format text: ORIGINAL CODE: EPIDOSCIGR1 |
|
GRAS | Grant fee paid |
Free format text: ORIGINAL CODE: EPIDOSNIGR3 |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): DE FR GB |
|
REG | Reference to a national code |
Ref country code: GB Ref legal event code: FG4D |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R096 Ref document number: 60243988 Country of ref document: DE Effective date: 20130103 |
|
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed |
Effective date: 20130808 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R084 Ref document number: 60243988 Country of ref document: DE Effective date: 20130912 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R097 Ref document number: 60243988 Country of ref document: DE Effective date: 20130808 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: PLFP Year of fee payment: 14 |
|
REG | Reference to a national code |
Ref country code: GB Ref legal event code: 746 Effective date: 20160105 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: PLFP Year of fee payment: 15 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: PLFP Year of fee payment: 16 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: PLFP Year of fee payment: 17 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 20210224 Year of fee payment: 20 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 20210217 Year of fee payment: 20 Ref country code: GB Payment date: 20210224 Year of fee payment: 20 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R071 Ref document number: 60243988 Country of ref document: DE |
|
REG | Reference to a national code |
Ref country code: GB Ref legal event code: PE20 Expiry date: 20220210 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GB Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION Effective date: 20220210 |