United States Patent [19]
`United States Patent [19]
`McCoy et al.
`McCoyet a1.
`
`[54] DIAGNOSTIC SYSTEM FOR A CAPACITOR
`[54] DIAGNOSTIC SYSTEM FOR A CAPACITOR
`DISCHARGE IGNITION SYSTEM
`DISCHARGE IGNITION SYSTEM
`
`Inventors: Steven R. McCoy, Washington; Horst
`[75] Inventors: Steven R. McCoy, Washington; Horst
`[75]
`Scheel, Peoria, both of ID.
`Scheel, Peoria, both of 111.
`
`[73] Assignee: Caterpillar Inc., Peoria, ID.
`-
`.
`-
`-
`[73] Asslgnee. Caterpillar Inc, Peoria, 111.
`[21] Appl. No.:
`946,491
`[21] APPI' N05
`946,491
`[22] PCP Filcd:
`May 27, 1992
`[22] PCf Filed:
`May 27, 1992
`
`[86] PCfNo.:
`[86] PCT No.:
`
`PCTIUS92104S15
`PCT/[1592104515
`
`Nov. 9, 1992
`§ 371 Date:
`N0“ 9’ 1992
`§371 Date:
`§ 102(c) Date: Nov. 9’ 1992
`§ 102(e) Date: Nov. 9, 1992
`
`[87] PCT Pub. No; WO92/21876
`[87] PCf Pub. No.: W092121876
`
`PCf Pub. Date: Oct. 12, 1992
`PCT Pllb- Date: Oct 12, 1992
`lot. CL 6
`[51] Int. 01.6 ............................. .. F02P 5/145; F02P 17/00
`............................... F02P 5/145; F02P 17100
`[51]
`[52] us. Cl. ............ .. 324/393; 123/605; 324/388;
`[52] U.S. CI ........................... 324/393; 123/605; 3241388;
`324,391
`3241391
`,
`[58] Field of Search ..................................... 3241380, 388,
`80i 578;:
`[58] new of
`3241391,393,399,402; 73/116, 117.3;
`61’23
`’
`’
`’
`’
`’
`123/605
`,6 5
`
`[56]
`[56]
`
`_
`References Cited
`References cued
`U.S. PATENT DOCUMENTS
`U.S. PATENT DOCUMENTS
`
`111982 Frank et al ..............•....•.•.•••••. 3241391
`4,312,043
`4,312,043
`1/1982 Frank et a1. .......................... .. 324/391
`1111983 Kamamura et al ...•................. 3241391
`4,413,508
`5315mm 8t 31-
`-
`511991 Ookawa .................................. 3241388
`5,019,779
`,
`,
`o awa ......... ..
`5,060,623 10/1991 McCoy .
`123/605
`10/1991 McCoy .................................... 123/605
`5,060,623
`1011992 Ghaem .....................•.......••.••.• 3241391
`5,156,127
`5,156,127 10/1992 Ghaan ...................... .. 324/391
`
`II IIIII1IIIII1II
`IIIIIMIMM US005672972A
`
`USOO5672972A
`[11] Patent Number:
`Patent Number:
`[111
`[45] Date of Patent:
`[45] Date of Patent:
`
`5,672,972
`5,672,972
`Sep. 30, 1997
`Sep. 30, 1997
`
`5,208,540
`5/1993 Hoeflich .................................. 3241388
`5,208,540 5/1993 Hoe?ich ................................ .. 324/388
`5,216,369
`611993 Toyama ................................... 3241388
`5,216,369
`6/1993 Toyama ............. ..
`324/388
`8/1993 Sbimasaki et al ...................... 3241391
`5,237,279
`5,237,279
`8/1993 Shimasaki et a1. ................... .. 324/391
`FQREIGN PATENT DOCUMENTS
`FOREIGN PATENT DOCUMENTS
`
`0389775 1011990 European Pat. Off ..
`0 389 775 10/1990 European Pat. 01f. .
`5/1982 France.
`2493414
`2 493 414 5/1982 France .
`WO 88/01690 3,1988 WIPO ‘
`WO 88101690
`311988 WIPO.
`Primary Examiner-Maura K. Regan
`Primary &aminer-Maura K. Regan
`Attome» Agent, or Firm-Kirk A. Vander Leest; R. Carl
`?gs); Agent, or Fmn—K1rk A. Vander Leest; R. Carl
`Wilbur
`[57]
`[57]
`
`ABSTRACT
`ABSTRACT
`
`An apparatus is provided for monitoring ignition in indi
`An apparatus is provided for monitoring ignition in indi(cid:173)
`vidual cylinders of a multi-cylinder engine of the type
`vidual cylinders of a multi-cylinder engine of the type
`having an ignition system which includes a separate trans(cid:173)
`having an lgmuon system which 1nc1udes a separate trans
`former for each cylinder. Each transformer has primary and
`former for each cylinder. Each transformer has primary and
`secondary coils. The secondary coil is connected in series
`secondary coils. The secondary coil is connected in series
`with a spark gap in an associated one of the cylinders. The
`with a spark gap in an associated one of the cylinders. The
`ignition system further includes selector switches for receiv(cid:173)
`igni?°giilgstcmflmmcr,inciludcs fflccmr sv‘fitclhcs f“ “31.2"
`ing cylinder select signals and responsively connecting
`mg cy.
`‘I “fed 51g“ .s a“ raw?!“ Y °°‘“‘°? g
`respective transformer primary coils. The current flows
`1t:leuspec:v3l trans ormer ?nmaury? co is.
`e 1t:lugrrent t6 0;;
`through the primary coil resulting in a voltage potential
`oug
`epnrnaryco res nginavo epon
`across an associated spark gap which normally increases to
`across an associated spark gap which normally increases to
`a magnitude sufficient to cause a spark across the spark gap.
`a magnitude su?icient to cause a spark across the spark gap.
`A first circuit receives the cylinder select signals, senses time
`A?rst circuit receives the cylinder select signals, senses time
`delay between the reception of a cylinder select signal and
`delay between the reception of a cylinder select signal and
`sparking in a respective cylinder and responsively produces
`sparking in a respective cylinder and responsively produces
`a delay signal indicative of the sensed time delay. A diag
`a delay signal indicative of the sensed time delay. A diag(cid:173)
`nostics controller receives the delay signal, compares the
`nostics controller receives the delay signal, compares the
`delay signal to a plurality of preselected thresholds and
`delay signal to a plurality of preselected thresholds and
`responsively produces a status signal indicating the status of
`responsively produces a status signal indicating the status of
`ignition in a respective cylinder.
`'
`‘ti
`'
`cti
`lind .
`lgm on m a respe ve Cy
`Cr
`15 Claims, 10 Drawing Sheets
`15 Claims, 10 Drawing Sheets 7
`
`SAVE BEGIN TIME (BT)
`
`SIGNAL
`EIVED?
`
`r200
`
`205
`
`Yes
`
`( 210
`
`SAVE STOP TIME ($17
`
`l
`
`O
`
`No
`
`HAS MAXIMUM
`HAS MAXIMUM
`SPAAKDURATION
`SPARK DURATION
`TIME ELAPSED?
`TIME ELKPSED?
`
`215
`215
`
`You
`
`22°
`
`225
`
`STOP SIGNAL
`RECEIVED?
`
`No
`
`Yes SECONDARY DELAY TIME
`
`STOP we - seem ‘um-z
`
`STORE OPEN CIFICUIT
`FLAG
`
`230
`23°
`
`235
`
`S ET N EW
`DATA FLAG
`
`NIDEC and HONDA - Ex. 1016
`Nidec Corporation and American Honda
`Motor Co., Inc. - Petitioners
`
`1
`
`

`

`tj
`\C
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`
`5,672,972
`
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`

`

`u.s. Patent
`US. Patent
`
`Sep. 30, 1997
`Sep. 30, 1997
`
`Sheet 2 of 10
`Sheet 2 of 10
`
`5,672,972
`5,672,972
`
`(‘14
`14
`
`16a
`
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`L._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._. ___ .~
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`
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`4
`
`

`

`u.s. Patent
`U.S. Patent
`
`Sep. 30, 1997
`Sep.30, 1997
`
`Sheet 4 0f 10
`Sheet 4 of 10
`
`5,672,972
`5,672,972
`
`a:1-.....J
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`Z.....J(!J
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`L4~----r-----------~--~------- TIME
`
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`Q.....J w
`&3~b
`Q. VSP L-+--f---------------_ TIME
`en
`TIME
`
`5
`
`

`

`u.s. Patent
`US. Patent
`
`Sep. 30, 1997
`Sep. 30, 1997
`
`Sheet 5 of 10
`Sheet 5 of 10
`
`5,672,972
`5,672,972
`
`START
`
`J:.:r.g_ 7 _
`FIE-7
`
`SAVE BEGIN TIME (an
`SAVE BEGIN TIME (BT)
`
`STOP SIGNAL
`STOP SIGNAL
`RECEIVED?
`RECEIVED?
`
`No
`No
`
`No
`No
`
`HAS MAXIMUM
`HAS MAXIMUM
`SPARK DURATION
`SPARK DURATION
`TIME ELAPSED?
`TIME ELAPSED?
`
`Yes
`Yes
`
`STOP SIGNAL
`STOP SIGNAL
`RECEIVED?
`RECEIVED?
`
`No
`No
`
`200
`
`205
`205
`
`215
`215
`
`220
`220
`
`210
`
`(210
`
`SAVE STOP TIME (ST)
`SAVE STOP TIME (ST)
`
`225
`225
`
`SECONDARY DELAY TIME
`SECONDARY DELAY TIME
`-
`STOP TIME -_ BEGIN TIME
`STOP TIME - BEGIN TIME
`
`STORE OPEN CIRCUIT
`STORE OPEN CIRCUIT
`FLAG
`FLAG
`
`230
`/- 230
`
`235
`
`SET NEW
`DATA FLAG
`
`‘ END OF
`PROCESS
`
`6
`
`

`

`u.s. Patent
`US. Patent
`
`Sep.30, 1997
`Sep.30, 1997
`
`Sheet 6 of 10
`Sheet 6 of 10
`
`5,672,972
`5,672,972
`
`300 3 $
`[
`INITIALI POINTER ]
`
`302
`
`_
`
`‘
`
`l~g_B_
`LEE-E
`
`X .
`RETRIEvE DELAY TIME |
`|
`RETRIEVE DELAY TIME
`305 \
`$
`305
`DELAY TIME(DT)
`- DELAY TIME(DT) \
`UPDATED SINCE LAST
`UPDATED sINcE LAsT
`No
`No
`MAIN cONTROL LOOP? /
`MAIN CONTROL LOOP?
`310
`Yes
`310
`PRIMARY TO
`PRIMARY TO
`DT‘ M’ SECONDARY SHORT
`DT<=T1?
`SECONDARY SHORT
`Yes
`312 J
`312
`
`314
`
`I
`T1<DT<=T2?
`T1 <DT< =T2?
`
`320
`
`T2<DT<=T3?
`330 '1 No
`T3<DT<=T4?
`No
`
`340
`34o \
`
`‘
`OPEN CIRCUIT
`OPEN cIRcuIT
`
`Yes
`
`Yes
`
`Yes
`
`sEcONDARY sI-IORT
`
`r- 325
`315 -/
`NORMAL IGNITION
`
`,- 335
`f- 335
`PLUG MAINTENANCE
`» PLUG MAINTENANCE
`CONDmON
`cONDmON
`
`345
`345 N
`
`370
`37°
`
`‘I
`sAME FAuLT \
`SAME FAULT
`5 CONSECUTIVE TJMES?
`5 cONsEcuTIvE TIMES? /No
`No
`Yes
`V
`ENGINE LOAD
`ENGINE LOAD
`ABOVE MINIMUM?
`ABOVE MINIMUM?
`Yes
`Yes
`380
`II
`38° \
`SAVE DIAGNOSTJC
`sAvE DIAGNOSTIC
`IN FAULT CODE TABLE
`IN FAULT cODE TABLE
`
`No
`
`375
`375
`
`SECONDARY SHORT?
`sEcONDARY SHORT?
`No
`No
`
`Yes
`Yes
`
`385
`385
`
`~
`
`\ I-IAvE ALL sEcONDARY
`HAVE AU SECONDARY
`< DELAYs BEEN CHECKED?
`DELAYS BEEN CHECKED?
`
`No
`
`39° '\
`'NCHEMENT PO'NTER
`
`Yes
`
`rp
`w
`
`7
`
`

`

`u.s. Patent
`US. Patent
`
`Sep. 30, 1997
`Sep. 30, 1997
`
`Sheet 7 of 10
`Sheet 7 of 10
`
`5,672,972
`5,672,972
`
`EFL
`
`i
`
`400
`400,
`
`-------""='N":"'"o-« START ENGINE?
`No \ START ENGINE?
`Yes
`Yes
`
`405 -\
`405,
`DRIVER POINTER =1,
`DRIVER POINTER =1,
`COUNTERN=1
`cOuNTER N=1
`
`410 -\
`410~
`FIRE DRIVER AND
`FIRE DRIVER AND
`RECOVER DELAY TIME
`RECOVER DELAY TIME
`
`I
`
`,
`
`'
`
`42s
`
`41 5
`r416
`,..------<./ FIRST FIRING?
`‘
`FIRST FIRING? >
`Yes '----,r----
`Yes
`No
`NO
`L 425
`DT<NDT? >
`Yes ,,----,r---
`t------</ DT<NDT?
`Yes
`No
`NO
`I SET NDT=DT Jt-------i
`SET NDT= DT
`J
`420-1
`420
`
`430
`,430
`DRIvER POINTER
`DRIVER POINTER
`:C?
`=C1
`
`No
`
`Yes
`Yes
`
`435~
`435 N
`INCREMENT
`WCREMENT
`• DRIVER
`DRIVER
`POINTER
`POINTER
`
`,...-'--.....
`440
`440 """'\
`DRIVER POINTER =1,
`DRIVER POINTER =1,
`_
`N=101 ...... >--...
`“@F’ INOREMENT cOuNTER N
`INCREMENT COUNTER N ! - -
`-....-J/'No
`Yes
`Yes
`
`450~
`
`445../
`
`UPDATE
`UPDATE
`THRESHOLDS
`TI-IREsHOLDs
`T2-T4
`v T2-T4
`
`QL/
`
`8
`
`

`

`u.s. Patent
`US. Patent
`
`Sep. 30, 1997
`Sep. 30, 1997
`
`Sheet 8 of 10
`Sheet 8 of 10
`
`5,672,972
`5,672,972
`
`J----------
`
`I
`I
`
`TIME (20 AJS / DIV)
`TIME (20 JUS / DIV]
`
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`
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`
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`
`T
`3
`
`TIME (20 AJS / DIV)
`TIME (20 JUS / DIV)
`
`9
`
`

`

`u.s. Patent
`US. Patent
`
`Sep. 30, 1997
`Sep. 30, 1997
`
`Sheet 9 of 10
`Sheet 9 of 10
`
`5,672,972
`5,672,972
`
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`
`10
`
`

`

`u.s. Patent
`US. Patent
`
`Sep. 30, 1997
`Sep.30, 1997
`
`Sheet 10 of 10
`Sheet 10 of 10
`
`5,672,972
`5,672,972
`
`F-=r..g_l4_
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`
`TIME (50 JUS / DIV)
`TIME (50 JUS / DIV]
`
`11
`
`

`

`5,672,972
`5,672,972
`
`1
`1
`DIAGNOSTIC SYSTEM FOR A CAPACITOR
`DIAGNOSTIC SYSTEM FOR A CAPACITOR
`DISCHARGE IGNITION SYSTEM
`DISCHARGE IGNITION SYSTEM
`
`TECHNICAL FIELD
`TECHNICAL FIELD
`
`This invention relates generally to a diagnostic system for
`This invention relates generally to a diagnostic system for
`an internal combustion engine and, more particularly, to a
`an internal combustion engine and, more particularly, to a
`system for detecting electrical faults in a capacitor discharge
`system for detecting electrical faults in a capacitor discharge
`ignition system.
`ignition system.
`
`BACKGROUND ARf
`BACKGROUND ARI‘
`
`2
`2
`primary coils to a power source to induce current flow
`primary coils to a power source to induce current ?ow
`through a respective primary coil. The current ?ow through
`through a respective primary coil. The current flow through
`the primary coil results in a voltage potential across an
`the primary coil results in a voltage potential across an
`associated spark gap which normally increases to a magni
`associated spark gap which normally increases to a magni-
`5 tude sufficient to cause a spark across the spark gap. A first
`tude su?icient to cause a spark across the spark gap. A ?rst
`circuit receives the cylinder select signals, senses a time
`circuit receives the cylinder select signals, senses a time
`delay between the reception of a cylinder select signal and
`delay between the reception of a cylinder select signal and
`sparking in a respective cylinder and responsively produces
`sparking in a respective cylinder and responsively produces
`a delay signal indicative of the sensed time delay. A diag
`a delay signal indicative of the sensed time delay. A diag-
`nostic controller receives the delay signal, compares the
`10 nostic controller receives the delay signal, compares the
`delay signal to a plurality of preselected thresholds and
`delay signal to a plurality of preselected thresholds and
`responsively produces a status signal indicating the status of
`responsively produces a status signal indicating the status of
`ignition in a respective cylinder.
`ignition in a respective cylinder.
`In a second aspect of the present invention, an apparatus
`In a second aspect of the present invention, an apparatus
`is provided for monitoring ignition in an engine cylinder.
`15 is provided for monitoring ignition in an engine cylinder.
`15
`Ignition in the engine cylinder is controlled by an ignition
`Ignition in the engine cylinder is controlled by an ignition
`system which includes a transformer having primary and
`system which includes a transformer having primary and
`secondary coils, wherein the secondary coil is electrically
`secondary coils, wherein the secondary coil is electrically
`connected in series with a spark gap in the cylinder. The
`connected in series with a spark gap in the cylinder. The
`20 ignition system further includes a circuit for receiving a
`ignition system further includes a circuit for receiving a
`20
`cylinder select signal and responsively connecting the trans
`cylinder select signal and responsively connecting the trans(cid:173)
`former primary coil to a power source to induce current flow
`former primary coil to a power source to induce current ?ow
`through the primary coil which results in a voltage potential
`through the primary coil which results in a voltage potential
`across an associated spark gap. The current normally
`across an associated spark gap. The current normally
`25 increases to a magnitude sufficient to cause a spark across
`25
`increases to a magnitude su?icient to cause a spark arross
`the spark gap. A current sensing circuit senses a current
`the spark gap. A current sensing circuit senses a current
`?owing through the primary coil and responsively produces
`flowing through the primary coil and responsively produces
`a primary current signal. A monostable multivibrator is
`a primary current signal. A monostable multivibrator is
`adapted to receive the primary current signal and respon
`adapted to receive the primary current signal and respon-
`sively produce a stop time signal when the primary current
`30 sively produce a stop time signal when the primary current
`30
`signal reaches a preselected threshold which is su?icient to
`signal reaches a preselected threshold which is sufficient to
`cause a spark to arc the spark gap. A timer receives the
`cause a spark to arc the spark gap. A timer receives the
`cylinder select and stop time signals and produces a delay
`cylinder select and stop time signals and produces a delay
`signal in response to a time delay between the reception of
`signal in response to a time delay between the reception of
`the cylinder select and stop time signals. A diagnostic
`35 the cylinder select and stop time signals. A diagnostic
`35
`controller receives the delay signal and produces a primary
`controller receives the delay signal and produces a primary
`to secondary short signal in response to the delay signal
`to secondary short signal in response to the delay signal
`being within a first range of values, produces a secondary
`being within a ?rst range of values, produces a secondary
`short circuit signal in response to the delay signal being
`short circuit signal in response to the delay signal being
`40 within a second range of values which exceeds the first range
`within a second range of values which exceeds the ?rst range
`of values, produces a normal ignition signal in response to
`of values, produces a normal ignition signal in response to
`the delay signal being within a third range of values which
`the delay signal being within a third range of values which
`exceeds the first and second ranges of values, produces a
`exceeds the ?rst and second ranges of values, produces a
`plug maintenance signal in response to the delay signal
`plug maintenance signal in response to the delay signal
`45 being within a fourth range of values which exceeds the first,
`45
`being within a fourth range of values which exceeds the ?rst,
`second and third ranges of values, and produces an open
`second and third ranges of values, and produces an open
`circuit signal in response to the delay signal exceeding the
`circuit signal in response to the delay signal exceeding the
`first, second, third and fourth ranges of values.
`?rst, second, third and fourth ranges of values.
`
`Capacitor discharge ignitions (CDI’s) are well known in
`Capacitor discharge ignitions (CDI's) are well known in
`the art. Typically, CDl's include a charge storage
`the art. 'lypically, CDI’s include a charge storage
`mechanism, such as a capacitor, and a step-up transformer
`mechanism, such as a capacitor, and a step-up transformer
`with a secondary coil connected to a spark ignition device,
`with a secondary coil connected to a spark ignition device,
`such as a spark plug. A mechanism is provided to discharge
`such as a spark plug. A mechanism is provided to discharge
`the capacitor through the transformer primary coil in timed
`the capacitor through the transformer primary coil in timed
`relationship with a desired engine ignition sequence. Dis
`relationship with a desired engine ignition sequence. Dis(cid:173)
`charge of the capacitor through the transformer primary coil
`charge of the capacitor through the transformer primary coil
`induces a high voltage signal in the transformer secondary
`induces a high voltage signal in the transformer secondary
`coil, which, if sufficiently high, causes a spark to arc across
`coil, which, if su?iciently high, causes a spark to are across
`the spark plug gap. More speci?cally, the voltage applied
`the spark plug gap. More specifically, the voltage applied
`across a spark ignition device must be greater than or equal
`across a spark ignition device must be greater than or equal
`to a predetennined characteristic "spark ionization poten(cid:173)
`to a predetermined characteristic “spark ionization poten
`tial” (voltage) Vs,P in order to initiate the spark. Such
`tial" (voltage) V sp in order to initiate the spark. Such
`ionization potentials are typically on the order of 10 Kv or
`ionization potentials are typically on the order of 10 Kv or
`more. The ionization potential V Sp is dependent on factors
`more. The ionization potential VSP is dependent on factors
`such as spark plug gap, cylinder pressure, engine load, and
`such as spark plug gap, cylinder pressure, engine load, and
`air/fuel ratio.
`air/fuel ratio.
`Typically, a CDI includes a separate transformer for each
`Typically, a CD1 includes a separate transformer for each
`engine cylinder. As such it is possible for electrical faults,
`engine cylinder. As such it is possible for electrical faults,
`such as an electrical short in a transformer secondary circuit,
`such as an electrical short in a transformer secondary circuit,
`to occur in anyone of the engine cylinders. Such a fault will
`to occur in any one of the engine cylinders. Such a fault will
`result in a deterioration of the overall engine operation and,
`result in a deterioration of the overall engine operation and,
`therefore, it is desirable to be able to detect such faults.
`therefore, it is desirable to be able to detect such faults.
`However, to date little work has been done in providing
`However, to date little work has been done in providing
`detection and diagnostics of electrical faults in the trans(cid:173)
`detection and diagnostics of electrical faults in the trans
`former secondary circuit.
`former secondary circuit.
`Currently, when a fault is suspected, the first step typically
`Currently, when a fault is suspected, the ?rst step typically
`is to replace or regap all the spark plugs in the engine. If this
`is to replace or regap all the spark plugs in the engine. If this
`does not correct the problem, it is common to systematically
`does not correct the problem, it is common to systematically
`replace individual transformers until proper engine perfor
`replace individual transformers until proper engine perfor(cid:173)
`mance resumes. Such methods result in substantial delays in
`mance resumes. Such methods result in substantial delays in
`downtime and lost productivity from the engine. Therefore,
`downtime and lost productivity from the engine. Therefore,
`it is desirable to provide a means for detecting electrical
`it is desirable to provide a means for detecting electrical
`faults in the secondary circuits of individual engine cylin(cid:173)
`faults in the secondary circuits of individual engine cylin
`ders and to provide an indication of the particular type of
`ders and to provide an indication of the particular type of
`fault that is detected
`fault that is detected.
`The subject invention is directed toward addressing one or 50
`The subject invention is directed toward addressing one or
`more of the problems as set forth above by providing a
`more of the problems as set forth above by providing a
`diagnostic system for a capacitor discharge ignition system
`diagnostic system for a capacitor discharge ignition system
`which can detect a variety of electrical faults in individual
`which can detect a variety of electrical faults in individual
`cylinders. Furthermore, the subject invention is capable of
`cylinders. Furthermore, the subject invention is capable of
`providing an indication of when individual spark plugs need
`providing an indication of when individual spark plugs need 55
`to be replaced or regapped.
`to be replaced or regapped.
`
`DISCLOSURE OF TIlE INVENTION
`DISCLOSURE OF THE INVENTION
`In one aspect of the present invention, an apparatus is
`In one aspect of the present invention, an apparatus is
`provided for monitoring ignition in individual cylinders of a
`provided for monitoring ignition in individual cylinders of a
`rmllticylinder engine of the type having an ignition system
`multicylinder engine of the type having an ignition system
`which includes separate transformers for each cylinder. Each
`which includes separate transformers for each cylinder. Each
`transformer has primary and secondary coils. The secondary
`transformer has primary and secondary coils. The secondary
`coils are electrically connected in series with spark gaps in
`coils are electrically connected in series with spark gaps in
`associated engine cylinders. The ignition system further
`associated engine cylinders. The ignition system further 65
`65
`includes a switching circuit for receiving cylinder select
`includes a switching circuit for receiving cylinder select
`signals and responsively connecting respective transformer
`signals and responsively connecting respective transformer
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is an illustrative block diagranI of a capacitive
`FIG. 1 is an illustrative block diagram of a capacitive
`discharge ignition system which can be adapted for use with
`discharge ignition system which can be adapted for use with
`the immediate invention;
`the immediate invention;
`FIG. 2 is a circuit diagram of the capacitive discharge
`FIG. 2 is a circuit diagram of the capacitive discharge
`ignition system of FIG. 1;
`ignition system of FIG. 1;
`FIG. 3 is a circuit diagram of the ignition system of FIGS.
`FIG. 3 is a circuit diagram of the ignition system of FIGS.
`1 and 2 incorporating the immediate invention;
`1 and 2 incorporating the immediate invention;
`FIG. 4 is a graph of a cylinder select signal during an
`FIG. 4 is a graph of a cylinder select signal during an
`ignition cycle;
`60 ignition cycle;
`FIG. 5 is a graph of the current through a primary coil
`FIG. 5 is a graph of the current through a primary coil
`during an ignition cycle;
`during an ignition cycle;
`FIG. 6 is a graph of secondary voltage during an ignition
`FIG. 6 is a graph of secondary voltage during an ignition
`cycle;
`cycle;
`FIG. 7 is a software flowchart illustrating a Delay Time
`FIG. 7 is a software ?owchart illustrating a Delay Time
`Subroutine which is performed to measure spark delay times
`Subroutine which is performed to measure spark delay times
`for individual cylinders;
`for individual cylinders;
`
`12
`
`

`

`5,672,972
`5,672,972
`
`5
`
`3
`3
`FIG. 8 is a software flowchart illustrating a Diagnostic
`FIG. 8 is a software ?owchart illustrating a Diagnostic
`Subroutine performed by the immediate invention;
`Subroutine performed by the immediate invention;
`FIG. 9 is a software flowchart illustrating a Delay Time
`FIG. 9 is a software ?owchart illustrating a Delay Time
`Initialization Subroutine;
`Initialization Subroutine;
`FIG. 10 is a graph of the primary current for a transformer
`FIG. 10 is a graph of the primary current for a transformer
`having a primary to secondary short circuit;
`having a primary to secondary short circuit;
`FIG. 11 is a graph of the primary current for a transformer
`FIG. 11 is a graph of the primary current for a transformer
`having a secondary short circuit;
`having a secondary short circuit;
`FIG. 12 is a graph of the primary current for a transformer
`FIG. 12 is a graph of the primary current for a transformer
`during a normal ignition cycle;
`during a normal ignition cycle;
`FIG. 13 is a graph of the primary current for a transformer
`FIG. 13 is a graph of the primary current for a transformer
`during a spark plug maintenance condition;
`during a spark plug maintenance condition;
`FIG. 14 is a graph of the secondary voltage for a trans(cid:173)
`FIG. 14 is a graph of the secondary voltage for a trans
`former having a secondary open circuit; and
`former having a secondary open circuit; and
`FIG. 15 is a graph of the primary current for a transformer
`FIG. 15 is a graph of the primary current for a transformer
`having a secondary open circuit;
`having a secondary open circuit;
`BEST MODE FOR CARRYING our THE
`BEST MODE FOR CARRYING OUT THE
`INVENI'ION
`INVENTION
`Referring now to the drawings, the immediate engine
`Referring now to the drawings, the immediate engine
`diagnostic system S will be described in connection with a
`diagnostic system S will be described in connection with a
`capacitor discharge ignition system 10. The diagnostic sys
`capacitor discharge ignition system 10. The diagnostic sys(cid:173)
`tem 8 can be adapted for use with numerous capacitor 25
`tem 8 can be adapted for use with numerous capacitor
`25
`discharge ignition systems, ‘as should be apparent to one
`discharge ignition systems, as should be apparent to one
`skilled in the art. However, ihe diagnostic system 8 will be
`skilled in the art. However, the diagnostic system 8 will be
`described in connection with an ignition system as disclosed
`described in connection with an ignition system as disclosed
`in U.S. Pat. No. 5,060,623 which issued on Oct. 29, 1991 to
`in U.S. Pat. No. 5,060,6B which issued on Oct. 29, 1991 to
`McCoy and the disclosure of which is speci?cally incorpo
`McCoy and the disclosure of which is specifically incorp~ 30
`rated by reference.
`rated by reference.
`The ignition system 10 is shown generally in FIGS. 1 and
`The ignition system 10 is shown generally in FIGS. 1 and
`2 FIG. 3 illustrates the ignition system 10 incorporating the
`2. FIG. 3 illustrates the ignition system 10 incorporating the
`immediate diagnostic system 8. The diagnostic and ignition
`immediate diagnostic system 8. The diagnostic and ignition
`systems 8,10 will work with an internal combustion engine 35
`systems 8, 10 will work with an internal combustion engine
`35
`having any number of cylinders provided electrical compo
`having any number of cylinders provided electrical compo(cid:173)
`nents are sized properly. Currently, the diagnostic and igni
`nents are sized properly. Currently, the diagnostic and igni(cid:173)
`tion systems 8,10 are being developed for use with a series
`tion systems 8,10 are being developed for use with a series
`3500 SI engine as manufactured by Caterpillar Inc. of
`3500 SI engine as manufactured by Caterpillar Inc. of
`Peoria, m. The series 3500 SI engine has 16 cylinders; 40
`Peoria, Ill. The series 3500 SI engine has 16 cylinders;
`however, for simplification FIG. 1 is described in connection
`however, for simpli?cation FIG. 1 is described in connection
`with a six cylinder engine and FIGS. 2 and 3 are illustrated
`with a six cylinder engine and FIGS. 2 and 3 are illustrated
`in connection with a single engine cylinder.
`in connection with a single engine cylinder.
`The ignition system 10 includes a power source 12, such
`The ignition system 10 includes a power source 12, such
`as a battery, connected to a DC-t~DC power converter 14. 45
`as a battery, connected to a DC-to-DC power converter 14.
`45
`The power converter 14 is a continuously operating, high
`The power converter 14 is a continuously operating, high
`speed charging circuit, and it is electrically connected to first
`speed charging circuit, and it is electrically connected to ?rst
`and second terminals 16a,16b of an ignition capacitor 18.
`and second terminals 16a,16b of an ignition capacitor 18.
`The power converter 14 is provided for rapidly charging the
`The power converter 14 is provided for rapidly charging the
`ignition capacitor 18 and continuously supplying power to
`ignition capacitor 18 and continuously supplying power to 50
`the capacitor 18 to maintain the capacitor first terminall6a
`the capacitor 18 to maintain the capacitor ?rst terminal 16a
`at a predetermined electrical potential above the capacitor
`at a predetermined electrical potential above the capacitor
`second terminal 16b. More particularly, the capacitor second
`second terminall6b. More particularly, the capacitor second
`terminal 16b is connected to system ground and the first
`terminal 16b is connected to system ground and the ?rst
`terminal 160 is maintained a preselected potential Vc above
`terminall6a is maintained a preselected potential V c above 55
`system ground. In the preferred embodiment, the preselected
`system ground. In the preferred embodiment, the preselected
`potential V c is on the order of 200 volts. Power converters
`potential Vc is on the order of 200 volts. Power converters
`of this type are common in the art and, therefore, will not be
`of this type are common in the art and, therefore, will not be
`explained in greater detail. One such circuit is generally
`explained in greater detail. One such circuit is generally
`disclosed