EP0089429A1 - Zündkerze für Verbrennungsmotor - Google Patents

Zündkerze für Verbrennungsmotor Download PDF

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Publication number
EP0089429A1
EP0089429A1 EP82301507A EP82301507A EP0089429A1 EP 0089429 A1 EP0089429 A1 EP 0089429A1 EP 82301507 A EP82301507 A EP 82301507A EP 82301507 A EP82301507 A EP 82301507A EP 0089429 A1 EP0089429 A1 EP 0089429A1
Authority
EP
European Patent Office
Prior art keywords
spark
plug
electrode
engine
spark plug
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.)
Withdrawn
Application number
EP82301507A
Other languages
English (en)
French (fr)
Inventor
Gerald Moss
David Lyon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ExxonMobil Technology and Engineering Co
Original Assignee
Exxon Research and Engineering Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Exxon Research and Engineering Co filed Critical Exxon Research and Engineering Co
Priority to EP82301507A priority Critical patent/EP0089429A1/de
Publication of EP0089429A1 publication Critical patent/EP0089429A1/de
Withdrawn legal-status Critical Current

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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
    • H01T13/46—Sparking plugs having two or more spark gaps
    • H01T13/467—Sparking plugs having two or more spark gaps in parallel connection

Definitions

  • the present invention relates to a spark plug for an internal combustion engine, and to an ignition system and to an internal combustion engine comprising the spark plug.
  • thermodynamic efficiency of a spark ignition internal combustion engine is dependent, inter alia, on the timing of the combustion and the rate at which it occurs. The best results are obtained when combustion is completed very close to the top dead centre position of the crank, but although rapid combustion is desirable, excessively fast combustion causing knocking, which can damage the engine, must be avoided.
  • the present invention provides a spark plug for an internal combustion engine, the plug comprising a body having a central portion of electrically non-conductive material and a surrounding portion adapted for securing the plug relative to a spark plug hole of the engine, a plurality of spark electrodes at one axial end region of the plug intended to be disposed within a combustion chamber of the engine, a counter-electrode defining a spark gap with each spark electrode, and a respective electrical conductor for each spark electrode which conductor is disposed within the body and provides a respective electrically-conductive path through the body to the respective spark electrode from a respective electrical connection point or area at or near to the other axial end of the body for the application thereto of high-tension electricity, the electrical conductors being electrically insulated from each other within the body, wherein each spark electrode is offset from the central axis of the plug and has at least a projecting portion at or near to the end region of the body which extends away from the plug axis to a tip region of the spark electrode, and wherein the counter
  • the spark plug of the invention enables multi-spark ignition from a plurality of high-tension sources to be effected in the or each cylinder of an engine from a single spark plug thereby at least partially improving the efficiency of operation of the engine.
  • The-high-tension sources may be electrical conductors for conducting high-voltage electricity from a single originating source thereof or from a plurality of originating sources of high-voltage electricity whereby the sparks at each spark gap may appear either simultaneously together or separated in time.
  • the spark plug of the invention can be employed in place of a conventional spark plug having a single spark gap without the necessity of altering the cylinder head of the engine. The benefits of the new spark plug are therefore realisable on unmodified internal combustion engines.
  • the spark plug comprises a discrete counter-electrode for each spark electrode.
  • the tip of the projecting portion of each spark electrode is preferably in a radial plane which is further from the said other axial end of the body than the radial plane of the said one axial end of the body.
  • the or each counter-electrode defines one end of a respective spark gap in a radial plane which is between the radial plane of the tip of a corresponding spark electrode and the radial plane of the said one axial end of the body.
  • the spark plug of the invention is preferably devoid of any part which outwardly surrounds the spark gaps so that gases in the combustion chamber are substantially not physically inhibited or shielded from the sparks in the spark gaps by solid structures.
  • the plug may comprise three or more spark gaps defined between three or more spark electrodes and counter-electrodes.
  • the said surrounding part of the spark plug is preferably electrically conductive and may constitute at least part of, and/or may support, the counter-electrodes.
  • the tip of each spark electrode is substantially flat or blunt or obtuse where it defines one end of a spark gap, so as to avoid or reduce erosion by the sparks passing across the spark gap 20.
  • At least the tips of the spark electrodes are substantially equiangularly spaced around the axis of the plug so as to define spark gaps which are substantially equiangularly separated around the plug axis.
  • the said surrounding portion of the plug does not extend as far away from the said other axial end of the body as the said one axial end of the said central portion, and preferably, the surrounding portion is externally screw-threaded for engagement with corresponding internal screw-threads of the spark plug hole of the engine.
  • This invention also provides an ignition system for an internal combustion engine comprising a spark plug as described above, and for each spark electrode of the spark plug, a respective source of high tension electricity.
  • the invention further provides an internal combustion engine comprising at least one cylinder having at least one spark plug as described above engaged with the cylinder, and for each electrode of the (or each) spark plug, a respective source of high-tension electricity.
  • a respective source of high-tension electricity can be employed - e.g.an induction coil, or one based on piezo-electric effects or a solid state source.
  • the spark plug is generally indicated by 10 and comprises a body 11 in the form of a cylindrical rod of ceramic (or other suitable electrically-insulating material) in which are received three electrodes 12. In the illustrated cross-section, only one of the electrodes 12 is visible.
  • the electrodes 12 extend within the body 11 parallel to the axis thereof and each electrode protrudes from one end of the body 11 which is intended to be within a cylinder of an internal combustion engine, and the protruding part is extended or bent radially outwardly into a spark electrode 13.
  • the opposite end 14 of the electrode 12 protrudes from the other end of the body 11 and is also radially outwardly formed or bent.
  • the end 14 is received in a rigid cap 15 of suitable high-melting, electrically-insulating material such as a suitable plastics material which serves to maintain in position the ends 14 of the electrodes 12 and thereby maintain the electrodes 12 in a substantially fixed disposition relative to the body 11.
  • suitable high-melting, electrically-insulating material such as a suitable plastics material which serves to maintain in position the ends 14 of the electrodes 12 and thereby maintain the electrodes 12 in a substantially fixed disposition relative to the body 11.
  • the body is substantially fixedly received in a multi-part member 16 which has one part 17 provided with an external screw-thread 18 adjacent to the spark electrode for engagement of the spark plug 10 in the threaded bore (not shown) provided for the purpose in the cylinder head (not shown) of an internal combustion engine.
  • On the part 17 and facing each spark electrode 13 is a respective counter-electrode 19 (of which only one can be seen in the drawing) which is of electrically conductive material and which defines a respective spark gap 20 with the respective spark electrode 13.
  • the spark gas 20 is parallel to the longitudinal axis of the plug and radially off-set therefrom so as to be as exposed as possible on all sides to gas around the gap 20.
  • the multi-part member 16 is secured to the body 11 by any suitable fitting 21 which provides a substantially fluid-tight sealing relationship between the multi-part member 16 and the body 11, e.g. by compression between said one part 17 and another part 22 which is engaged therewith by screw threads.
  • suitable fitting 21 which provides a substantially fluid-tight sealing relationship between the multi-part member 16 and the body 11, e.g. by compression between said one part 17 and another part 22 which is engaged therewith by screw threads.
  • Other securing and sealing arrangements known in the art may be employed instead.
  • Each electrode 12 must be connectible independently of the electrodes to a source of high tension electricity.
  • the body 11 of the spark plug has a radial bore 23 for each electrode for receiving radially an electrical connector in electrical contact with the respective electrode 12.
  • a suitable electrical connector which can be radially.received in the bore 23 in electrical contact with the electrode 12 is a radial projection 24 mounted on the inner face of a springy arcuate clip 25 of electrically conductive material at one end of a cable 26.
  • the cable 26 is connected at its other end (not shown) to a respective source of high-tension electricity.
  • the bores 23 will preferably be sufficiently separated along the axial length of the spark plug's body 11 to permit the clips 25 to be attached to the spark plug 10 with at least sufficient separation that high tension electricity passes to the corresponding electrode 12 without discharging to an adjacent clip and/or another electrode 12.
  • sparks may be produced across the spark gaps either substantially simultaneously or in a "rippled" or non-simultaneous fashion, depending upon the result desired in the cylinder of the internal combustion engine in which the sparks are to be employed.
  • the spark plug of the invention enables combustion to be initiated and/or promoted at a plurality of points, thereby tending to improve the combustion of the fuel charge in the cylinder.
  • the spark plug 30 is seen to comprise a central ceramic insulator 31 in which are received three electrical conductors (not visible) which are connected near the top end (as shown) of the plug 30 to respective insulated cables 32 each having a push-fit electrical connector 33 at its free end for connection to a source of high-tension electricity.
  • the electrical conductors are each connected to a respective spark electrode 34 which protrudes from the bottom end (as shown) of the central insulator 32 initially parallel to the axis of the plug and after a short distance thereafter, is turned substantially radially outwardly away from the axis of the plug 30.
  • the central ceramic insulator 31 is surrounded at its lower end, and sealed to, a mild steel sleeve member 36, the bottom end 37 of which has external screw threads for engagement with internal screw threads of a spark-plug hole of an internal combustion engine.
  • An upper part 38 of the sleeve member 36 is formed with hexagonal flats around its circumference for engagement with a spanner or wrench.
  • the sleeve member 36 may be formed from several parts.
  • Three counter-electrodes 40 extend downwardly from the bottom end of the sleeve member 36 so as to define spark gaps 42 with the free end-faces of the spark electrodes 34.
  • the three spark gaps 42 of the plug 30 are substantially radial with respect to the axis of the plug.
  • the faces of the spark electrodes 34 and the opposed counter-electrodes at the ends of the spark gaps are flat, to reduce erosion during use.
  • the central insulator 31 has a ceramic sleeve immediately above the sleeve member 36 to reduce heat losses from the plug.
  • FIGs 4 and 5 show views of a spark plug 60 which is identical to the spark plug of Figs 2 and 3 except in the arrangement of the electrodes to form the spark gaps. Like parts in Figures 2 to 5 are given the same reference numerals.
  • the spark electrodes protrude from the bottom (as shown) end of the plug 60 initially substantially parallel to the plug axis but are thereafter outwardly turned so as to extend beneath the counter-electrodes 40 (i.e. in a direction substantially perpendicular to the plug axis) to define with the counter-electrodes 40 respective spark-gaps 42 which are substantially parallel to the plug axis.
  • the protrusion (known as the "reach") of the counter-electrodes beyond the end of the body of the plug 60 is approximately the same in the embodiment of Figs 4 and 5 as in the embodiment of Figs. 2 and 3 and is also approximately the same as the reach in a commercially-available single spark gap spark plug of the conventional type. It will be seen in Figs. 4 and 5 that the spark electrodes 42 present a substantially flat surface towards the counter-electrodes 40.
  • the engine was installed on test-bed and modified so that one cylinder had its intake and exhaust systems segregated from the other three so that the fuel-air mixture strength, temperature, humidity, homogeneity, inter alia, could be precisely controlled to the one segregated cylinder while the engine was operated using all four cylinders.
  • the segregated cylinder was provided with a piezo-electric transducer flush-mounted in the cylinder head, and by the use of suitable electronic equipment and software programmes, a large number of pressure cycles from the segregated cylinder were captured and analysed by an on-line computer system which supplied the information to a 'floppy disc' recorder for off-line data analysis.
  • a software programme was employed to calculate the indicated thermal efficiency of an individual cycle or the mean thermal efficiency of a population of cycles. The testing procedure had been evaluated thoroughly beforehand to confirm that it would give very precise test results.
  • Table 1 The results summarised in Table 1 are for the configuration of the spark gaps at right angles to the axis of the plug (as in Figures 2 and 3 of the drawings). Surprisingly, these results conclusively demonstrate a reduction in fuel economy using the triple electrode spark plug of Fig 2 in.comparison to performance when using the conventional single spark plug.
  • Table 2 The results given in Table 2 are for the spark plug of Figs. 4 and 5 of the drawings and surprisingly, it is conclusively demonstrated that there are positive improvements in fuel economy which progressively increase as the engine is run under leaner conditions (i.e.
  • the test results dramatically illustrate that a spark plug providing a plurality of sparks for ignition of the fuel-air charge in the cylinders of a gasoline engine reduces engine efficiency (in relation to the efficiency for a conventional single spark-gap plug) when the sparks traverse gaps which are radial with respect to the plug axis at the end region of the plug, and that the reduction in engine efficiency is increased as the engine is run with a fuel-air mixture which is leaner (i.e. containing less fuel). The thermal efficiency of the engine is similarly impaired.
  • a spark plug which provides a plurality of ignition sparks which are substantially parallel to the plug axis at the end region of the plug improves both the thermal efficiency and fuel economy of the engine compared to a conventional single spark-gap plug, and the thermal efficiency continues to be higher for the multi-gap spark plug than a conventional single-gap plug as the fuel-air mixture is weakened, and moreover, the fuel economy becomes progressively greater as the fuel-air mixture is weakened.
  • the improved engine performance demonstrated using the spark plug of the invention may be further improved by arranging for the spark gaps to be slightly displaced relative to each other in the axial sense, and still further improvements can be realised by initiating the sparks at the gaps at slightly different times during each cycle of the engine.
  • spark plugs illustrated are designed merely for testing purposes and that spark plugs according to the invention would preferably have anti-tracking ribbed ceramic insulators 31 without the surrounding heat-insulating sleeve.
  • connection of the high tension leads to the plug terminals 33 would preferably be via a single cap having the requisite number of terminals at the top of the plug.
  • the engagement would preferably be by means of 'push-fit' connectors, and the single cap may have male-type connectors which are adapted to be received and engaged by female sockets in the top of the plug.

Landscapes

  • Ignition Installations For Internal Combustion Engines (AREA)
EP82301507A 1982-03-23 1982-03-23 Zündkerze für Verbrennungsmotor Withdrawn EP0089429A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP82301507A EP0089429A1 (de) 1982-03-23 1982-03-23 Zündkerze für Verbrennungsmotor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP82301507A EP0089429A1 (de) 1982-03-23 1982-03-23 Zündkerze für Verbrennungsmotor

Publications (1)

Publication Number Publication Date
EP0089429A1 true EP0089429A1 (de) 1983-09-28

Family

ID=8189614

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82301507A Withdrawn EP0089429A1 (de) 1982-03-23 1982-03-23 Zündkerze für Verbrennungsmotor

Country Status (1)

Country Link
EP (1) EP0089429A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2275505A (en) * 1993-02-25 1994-08-31 Roy Targonski Multiple electrode spark plug
DE10329269A1 (de) * 2003-06-30 2005-01-27 Robert Bosch Gmbh Zündkerze mit mindestens zwei Mittelelektroden

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR459263A (fr) * 1912-08-31 1913-10-31 Edouard Herman De Mey Bougie multiple pour moteurs à explosion
US1335797A (en) * 1920-04-06 of toledo
FR519077A (fr) * 1920-07-06 1921-06-04 Pio Mei Perfectionnements apportés aux bougies des moteurs à explosion
DE595340C (de) * 1934-04-09 Richard Langer Hochspannungszuendkerze
FR1039839A (fr) * 1951-09-05 1953-10-09 Citroen Sa Andre Perfectionnement au montage des électrodes dans les bougies d'allumage
US3974412A (en) * 1975-02-03 1976-08-10 Massachusetts Institute Of Technology Spark plug employing both corona discharge and arc discharge and a system employing the same

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1335797A (en) * 1920-04-06 of toledo
DE595340C (de) * 1934-04-09 Richard Langer Hochspannungszuendkerze
FR459263A (fr) * 1912-08-31 1913-10-31 Edouard Herman De Mey Bougie multiple pour moteurs à explosion
FR519077A (fr) * 1920-07-06 1921-06-04 Pio Mei Perfectionnements apportés aux bougies des moteurs à explosion
FR1039839A (fr) * 1951-09-05 1953-10-09 Citroen Sa Andre Perfectionnement au montage des électrodes dans les bougies d'allumage
US3974412A (en) * 1975-02-03 1976-08-10 Massachusetts Institute Of Technology Spark plug employing both corona discharge and arc discharge and a system employing the same

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2275505A (en) * 1993-02-25 1994-08-31 Roy Targonski Multiple electrode spark plug
DE10329269A1 (de) * 2003-06-30 2005-01-27 Robert Bosch Gmbh Zündkerze mit mindestens zwei Mittelelektroden
DE10329269B4 (de) * 2003-06-30 2005-12-29 Robert Bosch Gmbh Zündkerze mit mindestens zwei Mittelelektroden

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19840118

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Withdrawal date: 19870413

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Effective date: 19870319

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Inventor name: MOSS, GERALD

Inventor name: LYON, DAVID