IE45580B1 - Spark plug contsuction for lean mixture burning internal combustion engines - Google Patents

Description

BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates in general to internal combustion engines, and more particularly to the construction of spark plugs or spark plug housing adaptors for each cylinder of 'multi-cylinder internal combustion engines providing an ignition chamber formed by a portion of the spark plug immediately surrounding the electrodes of the spark plug for ignition of a ! ..- i . rich combustible mixture producing flame for'readily igniting a .. lean combustible mixture.

Heretofore, it has been known that relatively lean •ombustible mixtures designed to maximize gasoline mileage in ‘ internal combustion engines is frequently difficult to ignite and often does not burn completely. This results in frequent misfiring or failure to fire the lean combustion mixture in the main combus15 tion chambers of the internal combustion engines using them and alsfa increases the air pollution caused by the exhaust from the internal combustion engine, both’ due to failure of ignition when this occurs and also due to failure of the mixture to burn completely even though ignition, may occur. 2o Some efforts to reduce air pollution resulting from noxious gases in the exhaust of internal combustion engines have involved addition of air injection pumps to the internal combustior engine, exhaust recycling systems to cut down the formation o£ smogproducing chemicals, and use of -catalytic converters fitted into the exhaust system of the automobile to convert harmful constituents of the engine exhaust into harmless chemical components or (Compositions. All of these measures involve adding on of additional or auxiliary devices to automobiles, and in-most cases have reduced the gasoline mileage attainable, thus increasing the · consumption of fuel energy and further compounding the already 4SSS0 difficult energy consumption problem.

Efforts have been made to achieve greater fuel economies in internal combustion engines and concurrently obtain greater f ' .reliability of ignition and more complete combustion by redesigning 5 the .engine‘.block to, define a smaller auxiliary c^mbu?'-;i;mber or-ignition chamber communicating with each respective main com• bustion chamber with a spark plug associated with each auxiliary combustion chamber·, having its electrode gap in the auxiliary combustion chamber apd with a valved fuel supply line to the auxiliary combustion chamber providing a rich fuel-air mixture to the auxiliary combustion chamber for reliable ignition and a second fuel mixture supply conduit supplying a lean fuel-air 'mixture to the main combustion chamber. Examples of such arrangements are found in the earlier U.S, Patents Nos. 3,844,259 and 3,853,097 granted to Honda Motor Co., Ltd. In such prior art systems the rich air-fuel mixture is supplied through an intake valve to the auxiliary combustion chamber specially formed in the engine block during the downstroke or suction stroke of the piston for the associated cylinder, and the rich mixture which is readily ignited by the associated spark plug produces a flame discharge communicating with the lean mixture supplied to the main combustion chamber during the same suction stroke of the piston ' to achieve more reliable ignition.and more complete combustion of the lean mixture. However, the designs employed in those prior - patented systems require specially formed engine blocks designed so that the configuration of the engine block provides for the auxiliary combustion chamber or ignition chamber in which ignition of the rich fuel-air' mixture occurs to produce the flame which achieves ignition of the ,leqw fuel-air mixture in the main com30 bustion chamber. That system of ignition is not adaptable for 45880 ;use in already existing conventional internal combustion engine blocks, because new engine blocks would be required to provide the special auxiliary combustion chamber configuration and valved rich !mixture intake supply system needed in those prior art designs.

An object of the present invention is the provision of ,’a novel replacement spark plug assembly for internal combustion engines having a main combustion chamber connected by a first fuel supply conduit to a first fuel source for supplying a lean fuelair mixture to the combustion chamber, wherein the replacement spark plug assembly incorporates an apertured shell or dome structure surrounding the electrode gap to define an auxiliary ignition chamber and includes within the assembly a valved intake conduit for communication through a supply conduit with a second fuel source to provide a rich fuel-air mixture in the auxiliary ignition chamber to achieve ignition and production of flame for igniting the lean fuel-air mixture in the main combustion chamber of the associated engine cylinder.

Another object of the present invention is the provision of a novel spark plug construction which may be fitted into conventional automobile engine heads in place of the standard spark plug and provide for ignition of a rich fuel-air mixture in a limited size ignition·chamber defined by the spark plug to produce flame for insuring ignition and more complete burning of a lean fuel-air mixture in the combustion chamber of the associated engine cylinder.

Another object of the present invention is the provision of a novel spark plug construction as defined in either of the two preceding paragraphs, wherein ignition in the auxiliary ignition chamber defined by the spark plug assembly is produced in such a -445580 manner· as to create high velocity turbulent air currents in the ignition chamber· which deters build-up of deposits within the chamber and on the spark gap electrodes of the sparx pluc,.

Other objects, advantages and capabilities of the present 5 invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings showing a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE FIGURES FIGURE 1 is a vertical section view of a spark plug constructed in accordance with the invention; FIGURE 2 is a section view taken along the line 2-2 of Fig. 1; FIGURE 3 is a vertical section view of another form of spark plug construction embodying the present invention, wherein a conventional spark plug is assembled in an adaptor housing member; and FIGURE 4 is a bottom view of the assembly of Fig. 3. -545580.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT ' . · Referring to the drawings, wherein like·reference ιcharacters designate corresponding parts throughout the several figures, and particularly to Figs. 1-2, the improved spark plug of the present invention, indicated generally by the reference character 10, has the general configuration of conven1tional spark plugs, and comprises a lower metallic housing portion • 12 having a hexagonal nut formation 14 at its upper portion and .haying· .a lower portion 16 of reduced diameter which is externally threaded at 18 to screw into an opening in the cylinder head of 1 an internal combustion engine. The lower housing portion 12 defines an upwardly opening bote through the major portion of its length having a lower portion 20 of constricted cross section and an upper portion 22 of larger cross section terminating in an internally threaded·enlarged upper end portion 24 threaded to receive an insulator retainer nut 26 therein. Removably seated in the bore portions 20 and 22 is a generally cylindrical tubular insulator body 28 formed of hard ceramic material such as that ‘conventionally used for spark plugs having an enlarged intermediate collar or flange formation 30 seated against the transition shouldejr between the lower and' upper bore portions 20, 22 and clamped agains[t the transition shoulder by the insulator retainer nut 26.

The lower gradually tapering· portion 32 of the insulator body 28 is enclosed'by the threaded part of the lower portion 16 of the metallic housing 12 and by a dome portion 34 integral with the threaded portion and preferably having a frustaconical configuration providing a plurality, of circumferentially spaced inclined .ports 36. The lower end. of the dome formation 34 is flat and preferably formed at its center with a short rod section forming Ithe negative electrode 38 of the spark plug. The housing member 12 with its lower dome formation 34 and the lower tapered end (portion 32 of the insulator body 28 cooperate to define the lignition chamber or auxiliary combustion chamber 40 around the gap defined by the negative electrode 33 and the elongated positive center electrode rod 42 extending through the center of the insulator body 28.

I The insulator body 28 is suitably bored to accommodate the center electrode rod 42 along the center axis thereof, and .means are provided for adjustment of the spark gap by axial adjustment of the center electrode rod 42 in the insulator body 28. To this end, the upper portion of the center electrode rod 42 has a threaded portion 42a surrounded by an annular bushing 44 which extends into the larger diameter upper portions of the central bore 46 through the insulator body and having threads either preformed in the bore of the bushing 44 or deformed therein by the threaded portion of the center electrode 42 for threadedly 'coupling·the center electrode rod in the bushing so that rotation of the center electrode rod 42 effects axial movement of the center electrode within the insulator body 28. A lock nut 48 is threaded onto the threaded portion of the center electrode rod 42 immediately above and bearing against the bushing 44 to lock the . center electrode in its adjusted position, and a cap 50 may be braised or otherwise fixed on the top of the center electrode rod 42 to provide a suitable terminal for attachment of the ungrounded conductor from the automobile engine distributor to the center electrode.

An inclined lateral branch excursion 12a of the metallic housing member 12 provides a 'rich fuel supply conduit 52 communica-{ ting with the ignition chamber 40 at a level spaced slightly above the lower end of the tapered portion 32 of the insulator body and inclining upwardly to an enlarged diaineter internally threaded bore portion 54 into which an intake valve fitting 85 is threaded. The , intake valve fitting 85 has a lower threaded end portion threaded into the bore portion 54 and defines an enlarged valve chamber 86 immediately below the lower end of fitting 85 in the lower part of the larger bore portion of excursion 12a into which the fitting 85 is threaded. The fitting 85 has a lower constricted or smaller diameter bore portion 87a of cylindrical configuration for receiv10 ing and slidably guiding a valve stem 88 and an upper enlarged bore portion 87b opening through the upper end of the fitting 85 for housing a valve biasing spring assembly 89. The intake valve fitting 85 is externally threaded at its upper end for attachment to a rich fuel line, (not shown), extending to a carburetor, for ' example to a rich fuel supply port of the carburetor.

The spark plug 10 of the present invention is designed to be threaded into the usual threaded port for the conventional spark plug for the cylinder head of the engine defining the top of the cylinder to be served by the spark plug, for example, in a lateral inclined position wherein the spark plug is threaded into the usual spark plug port in the upper portion of the cylinder adjacent the usual fuel inlet valve controlling the intake port from the main carburetor.

The portion of the valve stem member 88 which slides in the constricted bore portion 87a is of fluted or non-round configuration, as by providing flats along the side of the larger diam.eter stem portion 88 as shown in Fig. 2 to provide passages for the . gas mixture to flow through the bore portion 87a. The lower end portion of the valve stem member 88 is of slightly reduced diam30 eter and is threaded, and an annular valve 90, for example of high 8<48580 temperature steel, is assembled on the threaded lower stem portion and is held thereon by nut 91 which is, for example, shrunk fit at elevated temperature onto the threaded portion to look tho valve thereon or the valve may be machined from one piece of high temperature steel. An annular valve seat insert 92, also of high temperature steel or similar material, is positioned for example, by shrink fitting, in a conforming enlargement at the lower end of the constricted bore portion 87a. The valve member 90 is normally biased to closed position against the valve seat insert 92 by the spring assembly 89, formed of a coil spring 89a and a pair of spiders or relieved washers 89b surrounding an upper reduced portion of the valve stem and shaped or relieved to pass the gaseous mixture therearound. The lower spider or washer 89b bears against the upper transition wall of the constricted bore portion 87a and the upper one is held by a suitable lockwasher and nut indicated at 93 or by a snap ring. The fuel intake supply line extending to the source of the fuel mixture to be supplied through the branch conduit 52 is connected to the upper end of the fitting 85.

In the operation of the engine with spark plug assemblies of the construction shown in Figs. 1-2 mounted in the top of each cylinder, it will be appreciated that when the piston for the associated cylinder is moving through its down stroke or suction stroke, the reduced pressure in the cylinder causes the valve member 90 on the slidable stem 88 to move downwardly away from the valve seat insert 92 against the bias of the spring assembly 89, opening the valve in the branch passage and permitting the fuel mixture designed to insure combustion in the auxiliary ignition chamber 40 to be drawn through the valve assembly and conduit 52 into the ignition chamber 40. On the next upstroke or compression stroke of the cylinder, the fuel drawn through the branch conduit and valve from whatever source it is connected thereto, it is then mixed within the auxiliary ignition chamber 40 with the regular fuel-air mixture, for example the lean fuel-air mixture, which was also supplied to the cylinder during the suction stroke, caus5 ing a thorough intermixing within the ignition chamber 40 by what we call turbo action as gases are forced through the horizontally and vertically inclined ignition ports 36. Then when the distributor supplies voltage to the cap of the positive center electrode 42 of the spark plug at the conclusion of the upstroke or compres10 sion stroke, the mixture in the ignition chamber 40 readily ignites and the resultant flame produced by the ignition exits as a hot jet of flame whirling through the ignition ports 36 into the upper portion of the main combustion chamber defined by the cylinder, by what we call ''retro-turbo action, to insure ignition of the mixture in the main combustion chamber. The flame is discharged in a whirling pattern due to the dispostion of the ignition ports 36 in the dome 34, as the axes of the ports are inclined downwardly and outwardly at a suitable angle, for example, approximately 45 degrees, from the vertical center axis of the spark plug and are also in20 dined at a suitable horizontal angle of, for example, approximately 45 degrees from the radii of the center axis of the spark plug.

The retro-turbo action produced by this whirling flame discharged from the ignition chamber 40 prevents the buildup of deposits within the ignition chamber, thus reducing the need for periodic main25 tenance and extending the performance life of the spark plug, and insures reliable ignition of the lean air-fuel mixture in the main combustion chamber which, through the use of the leaner gasoline mixture for the primary power for propelling the automobile, improves the efficiency of the ehgine, reduces gasoline consumption, -1045580 and reduces the emission of noxious exhaust fumes because of the more complete burning of the mixture achieved with this spark plug construction.

Another embodiment is illustrated in Figs. 3-4, wherein an adaptor generally indicated at 101 is designed to be assembled with the use of a conventional spark plug or a slightly modified conventional plug having its negative electrode removed, and is arranged to have components assembled thereto defining the branch passage and the valve mechanism therefor, thus permitting the con10 cept of the present invention to be realized with substantially conventional spark plugs. In the embodiment shown in Figs. 3-4, the adaptor 101 comprises a body 102 shaped at its lower end to define a dome portion 103 shaped like that of the previously described embodiment, which is externally threaded as indicated at 104, along its upper portion to screw into the usual spark plug opening in the cylinder head of an internal combustion engine. The lower end portion of the dome formation is of substantially the same configuration as the frustoconical wall of the previous embodiment and is provided with a plurality of circumferentially spaced inclined ports 105 shaped and inclined like the ports 36. The lower end of the dome formation 103 is flat and is provided with a threaded opening at its center to receive an elongated electrode member 106 providing the center negative electrode or cathode of the spark plug in cases where the regular lower negative electrode of the conventional spark plug is removed so that the gap is defined by the center positive electrode extending through the standard spark plug and this negative electrode member 106. The adaptor 101 preferably has a hexagonal nut formation along its upper body portion to facilitate mounting of the adaptor in the cylinder head, / -114SB8° and defines a chamber extending upwardly from and communicating with the ignition chamber 107 defined by the dome portion to receive the lower body portion of the conventional spark plug, the upper chamber 108 being threaded at its upper end to receive the threads of the usual spark plug. In most cases, a ceramic ferrule 108a is provided in the chamber 108 to regulate the volume of the ignition chamber 107. A branch bore 109 extends from the chamber 108 and is inclined at an angle thereto, and is internally threaded to receive the threaded lower end of the intake valve fitting 85 of the same construction described in connection with Figs. 1-2 in one embodiment, or to receive an elongated preheating conduit section 110, providing an internal fuel conducting passage 111 of selected length extending along the center axis of a metallic body 112 which is externally threaded at both ends. The threaded lower end of the metallic body 112 is threaded into the branch passage or bore 109 of the adaptor 101, and the upper end may be threaded into a connector 113 having an internal bore extending therethrough with internally threaded end portions 114 at its opposite ends sized and threaded appropriately to receive the threaded upper end of the preheating fuel conduit section 110 and the lower end of the intake valve fitting 85. The intake valve assembly for the embodiment of Figs.3and4has the same construction as the intake valve assembly of the embodiment of Figs. 1-2 and the parts thereof are identified by the same reference characters . -The operation of the embodiment illustrated in Figs. 3-4 is like that of the previously described embodiment, except that the elongated metallic preheating fuel conduit section 110 provides an elongated small conduit of appropriate length surrounded by metallic walls which become heated from the heat of the engine -1245580 block and surrounding components and effects preheating of the fuel being supplied to the ignition chamber 107 defined by the dome portion 103. This preheating conduit section ll'1 pnv .les a useful variation in which the branch passage defined by the preheating conduit section 110, the branch bore 109, the connector 113 and the valve assembly 85 may be connected through a fuel conduit, and through a distributing manifold.and metering valve, directly to a souroe of raw fuel, for example by connecting it directly to a standard carburetor fuel reservoir, or directly to the fuel line attached to the fuel pump. With this arrangement, a small amount . of the raw fuel regulated by the metering valve is drawn through the opened valve assembly 85 during the downstroke or suction stroke of the piston, to flow through the center passage 111 in the preheating fuel conduit section 110 and into the ignition chamber 107 defined by the dome portion 103 of the adaptor. This raw fuel is drawn into the plug chamber in very minute amounts during the downstroke of the piston, due to the configuration and construction of the valve assembly. When the engine is cold, this raw fuel drawn into the ignition chamber 107 is atomized by the turbo action which is produced in the ignition chamber 107 during the upstroke or compression stroke of the piston, during which some of the lean fuel-air mixture which was supplied to the main combustion chamber during the previous suction stroke is forced into the ignition chamber via the angled ports 105 to give the necessary air to the raw fuel within the ignition chamber for effective firing. Thus the fuel supplied from the branch passage into the ignition chamber is atomized and intermixed with lean fuel-air mixture by the turbo action within the ignition chamber during the upstroke or compression stroke and is then fired when voltage is supplied by the dis13tributor to the spark plug electrodes. When the engine becomes hot, the raw fuel being supplied through the branch passage as it flows through the passage 111 of the fuel conduit section 110 becomes preheated, and is then vaporized upon contact with the hot surfaces within the ignition chamber assisted further by the turbo action occurring on the compression stroke and intermixing with the lean fuel-air supply introduced from the main combustion chamber. The vaporization of the fuel by contact with the hot surfaces defining the walls and surfaces in the ignition chamber eliminate the possibility of condensation and resulting hydrocarbon emissions, while the turbo action which occurs within the ignition chamber due to the shaping and inclination of tha ports eliminates the danger of a blowout of the spark by keeping the fuel droplets suspended under cold start conditions.

It will be appreciated, of course, that, if desired, the first described embodiment of Figs. 1-2 could also be used in a system in which raw, unmixed fuel, for example as obtained from the carburetor float chamber or directly from a fuel line, could be supplied to the valved branch passage 52 controlled by the valve member 90 so that during the downstroke or suction stroke of the piston, a small amount of the raw fuel is drawn through the passage 52 into the ignition chamber 40, where it is intermixed by the turbo action with some of the lean air-fuel mixture introduced through the port 36 into the ignition chamber during the following compression strokes of the piston to provide a rich fuel-air mixture in the ignition chamber 40 which fires when voltage is applied to the electrodes of the spark plug to insure ignition of the lean fuel-air mixture in the main combustion chamber from the swirling flames thereupon discharged through the ports 36. Also, if desired, -14- . rather than introducing raw fuel of the same type that is employed in the lean fuel-air mixture supplied to the main combustion chamber, one may introduce a distinctly different ignitible fuel through the valve branch passage into the ignition chamber of any t of the previously described embodiment to insure ignition which then produces flames discharged through the ports to insure ignition of the lean fuel-air mixture in the main combustion chamber.

It has also been found that the retro-turbo action within the main cylinder chamber within the area surrounding the dome formation of the spark plug construction caused by the exit of the swirling flames from the angled ports 36 or 105 into the main combustion chamber results in more complete burning of the lean mixture in the cylinder, because of the resultant intermixing of the relatively colder fuel-air mixture accumulating around the relatively cold cylinder walls (which normally undergoes less complete combustion and causes hydrocarbon emissions), with the hotter fuel-air mixture within the main combustion chamber, thus reducing hydrocarbon emissions.

Claims (5)

1. A spark-ignition internal-combustion piston-engine, which comprises a spark plug assembly housing an elongated centre electrode rod which , extends the length of the spark plug assembly and terminates at the spark 5 gap, said spark plug assembly including a dome structure, the interior of which constitutes an ignition chamber surrounding the spark gap and which is formed with exit ports, and means for supplying fuel to the ignition chamber to produce a relatively rich fuel-air mixture therein, the spark plug assembly being so screw-mounted in a conventional spark-plug hole in 10 the engine that the dome structure protrudes into a cylinder of the engine, means for supplying a relatively lean fuel-air mixture to the cylinder, the said exit ports being so arranged and orientated that, upon ignition of the mixture in the ignition chamber by a spark across the spark gap, flames enter the cylinder through the exit ports to ignite the relatively lean 15 mixture therein, the ignited gases passing through the exit ports being so directed as to tend to promote vorticity in the mixture in the cylinder at least in the vicinity of the exterior of the dome structure, wherein valve means in the fuel supply to the ignition chamber comprises a valve seat and a valve member resiliently biased against the valve seat 20 and responsive to reduced pressure communicated from the cylinder during a suction stroke of the piston to open and admit fuel to the ignition chamber, and wherein the means for supplying fuel to the ignition chamber comprises a branch passage extending along a substantially rectilinear axis inclined to the axis of the centre electrode and diverging laterally 25 therefrom progessively from the inner end of the branch passage to its outer end, said branch passage having a larger diameter bore portion adjacent said outer end joining an elongated constricted-diameter bore portion located nearer said inner end, said valve member including an elongated valve stem of non-round cross section slidably positioned in ‘ 30 and guided by the constricted bore portion providing passage for fluid I i -. - 16 45380 flow through the constricted bore portion and having a larger diameter valve portion fixed to its end nearest said inner end, and spring means in the larger diameter bore portion biasing said valve member toward said outer end to closed position.

2. An engine as claimed in claim 1, which comprises a carburettor supplying the relatively lean fuel-air mixture and supplying a rich fuelair mixture to the means for supplying fuel to the ignition chamber.

3. An engine as claimed in claim 1 or 2, including a screw thread formation on the centre electrode threadedly coupled to internal screw threads on the spark plug assembly for axial movement of the centre electrode upon rotation thereof relative to the spark plug body for adjustment of the spark gap, and lock nut means coupled on the threaded formation on said centre electrode and abutting the body of the spark plug assembly to lock the centre electrode in position.

4. An engine as claimed in any one of claims 1 to 3, wherein the exit ports in the dome are openings having their centre axes inclined at a vertical angle of about 45 degrees to the centre axis of the spark plug body when the latter is disposed vertically and inclined at a horizontal angle of about 45 degrees to axes radiating orthogonally from the centre axis through the centres of the exit ports to direct the gas discharged through the ports in a whirling motion producing vorticity adjacent the spark gap. 5. An engine as claimed in claim 1, wherein the spark gap assembly comprises a conventional spark plug or a modified conventional spark plug having its negative electrode replaced, and an adaptor comprising a body shaped at its lower end to define a dome structure formed with exit ports and being externally threaded to screw into a conventional spark plug hole in the engine, the body being internally threaded at its upper end to receive the threads of a conventional spark plug so that the interior of the dome structure defines an ignition chamber surrounding the spark gap, and the body also having a branch bore to connect the branch passage to the ignition chamber. - 17 , . . 4S58Q 6. An engine as claimed in claim 1, wherein the branch passage includes an elongated pre-heating conduit section surrounded by metallic walls which become heated from the heat of the engine, said pre-heating conduit section being located between the valve means and the ignition chamber.

5. 7. An engine as claimed in claim 1 and substantially as hereinbefore described with reference to, and as shown in, Figures 1 and 2, or Figures 3 and 4· of the accompanying drawings.