(12) United States Patent
`J00s et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,725,835 B2
`Apr. 27, 2004
`
`US006725835B2
`
`(54) METHOD FOR OPERATING AN OTTO-
`CYCLE INTERNAL COMBUSTION ENGINE
`WITH FUEL INJECTION ON A COLD START
`
`(58) Field of Search .......................... .. 123/406.53, 491,
`123/436, 406.54, 406.55; 60/285
`
`(56)
`
`References Cited
`
`1/1991 Abe. ......................... .. 123/424
`4,982,712 A
`9/1991 Morlkawa ..
`123/305
`5,050,551 A
`10/1994 Ohtsuka . . . . . . .
`. . . . . .. 123/491
`5,357,928 A
`§:2§Z:§2§ 2 at 3133? $&;‘lffi‘:J:1‘.'.::::::::::...t??’§3%§§
`6,266,957 B1 *
`7/2001 N
`1
`1. ......... .. 60/284
`6,513,319 B2 *
`2/2003
`:1 :1.
`............. .. 60/284
`
`
`
`Il'lVCl'ltOI'SI Klaus JOOS,
`Daeubel, Markgroenmgen (DE); Gerd
`Grass, Schwjeberdjngen
`Ruediger Weiss, Moetzmgen (DE);
`Hansjoerg Bochum’ Lemfelden (DE);
`Edmund S°haut»Fri°1zheim<DE>
`.
`(73) Asstgooot Robert Bosch GmoH> Stuttgart (DE)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent 1s extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`JP
`
`FOREIGN PATENT DOCUMENTS
`11 280532
`9/1999
`OTHER PUBLICATIONS
`
`(21) Appl. No.:
`
`10/169,333
`
`(22) PCT Filed:
`(86) PCT No.:
`§ 371 (c)(1),
`(2), (4) Date:
`
`Dec. 27, 2000
`PCT/DE00/04633
`
`Sep. 16, 2002
`
`Patent Abstracts of Japan, Vol. 2000, No. 01, Jan. 31, 2000.
`*
`. d b
`.
`c1te
`y exammer
`d G,
`P ,
`E
`,
`_M h
`,
`1m1e
`rzmary xamzner
`a mou
`Assistant Examiner—Hai Huynh
`(74) Attorney, Agent, or Firm—Kenyon & Kenyon
`
`(87) PCT Pub. No.: W001/50015
`
`(57)
`
`ABSTRACT
`
`(65)
`
`PCT Pub. Date: Jul. 12, 2001
`Prior Publication Data
`Us 2003/0075152 A1 Apr, 24, 2003
`
`Foreign Application Priority Data
`(30)
`Dec. 31, 1999
`(DE)
`....................................... .. 199 63 914
`
`Int. Cl.7 ................................................. .. F02P 5/00
`(51)
`(52) U.S. Cl.
`................................. .. 123/406.53; 123/491
`
`A method is provided for operating a spark ignition internal
`b'
`'h'fl"'
`ld.Th
`com ust1on eng1ne
`aV1ng ue 1nject1on at a co
`start
`e
`method retards the spark angle to a cold start Value at least
`for the first combustion in at least one cylinder of the internal
`combustion engine during a cold start phase,
`the fuel
`injected into the cylinder being brought to combustion, and
`the Ihethed Sets the Spark angle t0 hehhal, t0 end the 00101
`start phase.
`
`8 Claims, 1 Drawing Sheet
`
`EX. 2001 1/
`
`Ex. 2001 1/5
`
`

`
`U.S. Patent
`
`Apr. 27, 2004
`
`US 6,725,835 B2
`
`EX. 2001 2/
`
`Ex. 2001 2/5
`
`

`
`US 6,725,835 B2
`
`1
`METHOD FOR OPERATING AN OTTO-
`CYCLE INTERNAL COMBUSTION ENGINE
`WITH FUEL INJECTION ON A COLD START
`
`FIELD OF THE INVENTION
`
`The present invention relates to a method of operating a
`spark ignition internal combustion engine having fuel injec-
`tion at a cold start.
`
`BACKGROUND INFORMATION
`
`To start a spark ignition internal combustion engine
`having direct fuel
`injection, an initial pressure of,
`for
`example, about 4 bar, may be created using an electrical fuel
`pump. The fuel
`injection may be limited by an angle
`window,
`the beginning of which may be defined by the
`moment of opening of an inlet valve and the end of which
`may be determined by the combustion chamber pressure
`established in the cylinder. Since the pressure in the com-
`bustion chamber rises during a compression phase and
`exceeds the initial pressure created by the electrical fuel
`pump starting at a certain piston position, the fuel injection
`should end when the pressure in the combustion chamber
`exceeds a certain pressure threshold. Otherwise, air may be
`blown from the combustion chamber into the inlet valve,
`which may cause this air, instead of fuel, to be injected
`through the inlet valve into the combustion chamber during
`a subsequent injection. This may disadvantageously cause
`combustion misfiring in the corresponding cylinders.
`Consequently,
`the beginning and the end of a fuel
`injection, which is limited by an angle window, are deter-
`mined by a certain rotational angle position of the
`crankshaft, the respective rotational angle positions at the
`beginning and end of the injection enclosing a correspond-
`ing variable angle of rotation of the crankshaft. The time
`interval during which the crankshaft passes through this
`angle of rotation is proportional to the rotational speed of the
`engine.
`When the internal combustion engine is cold-started, very
`long injection times may be required, at least for initial
`combustions. When the fuel injection times are long, the fuel
`reaching the combustion chamber from the first two injec-
`tions may combust and cause a significant
`increase in
`rotational speed. Due to the increase in rotational speed,
`there may not be sufficient injection time available for the
`subsequent third and fourth injections to inject an adequate
`quantity of fuel for combustion into the combustion chamber
`using the inlet valve (injection valve). This may cause
`unwanted combustion misfirings during the third and fourth
`injections at cold start.
`To avoid these unwanted combustion misfirings during
`the cold start, an additional injector (cold start injector),
`which may be positioned in the intake pipe of the engine,
`injects additional fuel into the injection chamber simulta-
`neously with the intake valve during the cold start. However,
`it is believed that such an additional cold start valve may be
`relatively complicated and costly.
`
`SUMMARY OF THE INVENTION
`
`An exemplary method according to the present invention
`for operating a spark ignition internal combustion engine
`having fuel injection at a cold start includes the following
`steps:
`retarding the spark angle to a cold start value for at least
`the first combustion in at least one cylinder of the
`
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`60
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`65
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`2
`internal combustion engine during a cold start phase,
`while the fuel injected into the cylinder is brought to
`combustion; and
`setting the spark angle to normal to end the cold start
`phase.
`Since the spark angle is retarded as much as possible for
`at least the first combustion in at least one cylinder, the fuel
`or fuel-air mixture injected into the combustion chamber is
`burned up in the corresponding ignition, and as such, a small
`torque is produced by this combustion.
`Consequently, the first combustion, using a retarded spark
`angle, results in a slight increase in rotational speed, so that
`there may be sufficient injection time available for the next
`injection to inject sufficient
`fuel
`into the combustion
`chamber, so that reliable combustion may be ensured, or at
`least made more probable. Further, since the combustion
`chamber warms up after the first combustion, less fuel may
`be injected into the combustion chamber to ensure a next
`combustion. Thus, a retarding of the spark angle for at least
`the first combustion in each respective cylinder during a cold
`start results in warming of the combustion chamber, while
`the increase in rotational speed of the engine is reduced. In
`this manner, successful combustion for the next injection is
`ensured, or at least made more probable, since less injected
`fuel may be required for the following combustion, due to
`the warming of the combustion chamber by the first
`combustion, while at the same time more injection time may
`be available for injecting fuel into the (warmed) combustion
`chamber due to the relatively slight increase in rotational
`speed. Thus, combustion misfirings during cold start may be
`prevented, or at least reduced, in a simple and reliable way.
`The cold start phase may include a plurality of combus-
`tions. Due to the low increase in rotational speed during the
`first combustions with a late spark angle, the retardation of
`the spark angle is not limited to the first combustion during
`the cold start, but may be extended to a desired optimal
`number of combustions to achieve effective warming of the
`combustion chamber and to optimize additional cold start
`parameters.
`The spark angle is reset to normal in a single step, to set
`a desired operating performance value. This permits a quick
`change from retarded spark angles to appropriate normal
`spark angles after the cold start phase ends, at which an
`elevated or maximum possible spark angle operating effi-
`ciency may be achieved.
`in a plurality of
`to normal
`The spark angle is reset
`transitional steps,
`to set a desired operating performance
`value. To avoid too great a change in the spark angle, the
`reset to normal, which ends the cold start phase, may occur
`in several transitional steps, until the desired normal spark
`angle is set to utilize maximum possible spark angle oper-
`ating efficiency.
`According to an exemplary embodiment of the present
`invention, the cold start value is individually set for each
`cylinder. Since the cold starting response of the various
`cylinders of an internal combustion engine may differ, a cold
`start value for each individual cylinder may be calculated
`and set,
`to ensure effective prevention of combustion
`misfirings, while at the same time maintaining the maximum
`possible spark angle efficiency.
`The cold start value may be set during the cold start phase
`for the next combustion of each corresponding cylinder.
`Since increased warming of the combustion chamber is
`achieved during the cold start phase with each combustion,
`a specific cold start value for each individual cylinder for
`each individual combustion may be calculated and set. In
`this manner, the retardation of the spark angle during the
`
`EX. 2001 3/
`
`Ex. 2001 3/5
`
`

`
`US 6,725,835 B2
`
`3
`cold start phase is kept as small as possible, so that an
`optimized spark angle operating efficiency may be attained,
`even during the cold start phase.
`The cold start value is set using a retardation setting that
`is adapted to the operating temperature of a particular
`cylinder. In this manner, the cold start value of the spark
`angle may be kept at the lowest level possible, to achieve
`optimal spark angle operating efficiency, while reliably
`preventing combustion misfirings during the cold start
`phase.
`The spark angle is retarded if the number of ignitions is
`smaller than or equal to the value of a parameter, which is
`greater than or equal to one and less than or equal to the
`number of cylinders in the engine, and the combustion
`chamber temperature before the first ignition is lower than a
`threshold temperature. This permits the retardation during
`the cold start phase to be limited to a defined number of
`ignitions, for example, alternative polling. The combustion
`chamber temperature before the first ignition may be at least
`approximately determined from the coolant temperature, the
`oil
`temperature and/or the intake air temperature of the
`engine. The temperature threshold may be, for example,
`approximately 0° C.
`
`10
`
`15
`
`20
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`25
`
`The FIGURE is a block diagram of a cold start spark
`angle adjustment.
`
`DETAILED DESCRIPTION
`
`The FIGURE is a block diagram of a cold start spark
`angle adjustment, in which the following definitions apply:
`Block 10=start of the cold start spark angle adjustment;
`Block 11=parameter acquisition with the parameters
`n=freely applicable number where 1§n§number of
`cylinders,
`z=number of ignitions;
`Block 12=alternative polling;
`Block 13=spark angle retardation AZWJ,;
`Block 14=spark angle normal setting AZW’|‘;
`Block 15=end of the cold start spark angle adjustment.
`When the internal combustion engine is started (Block
`10), the cold start spark angle adjustment is started auto-
`matically. The freely applicable number designated as n (for
`example lénénumber of cylinders in the engine) and the
`number of ignitions designated as Z are defined as param-
`eters (Block 11). These parameters n and Z are suitably
`determined. Before the first ignition, Z has the value 0. When
`the engine is cold started, an automatic alternative polling
`(Block 12) determines whether the number of ignitions Z is
`smaller than or equal to the number of cylinders n in the
`engine (z§n?), and whether, at the same time, the combus-
`tion chamber temperature in the cylinder before the first
`ignition is lower than a temperature threshold Ts (To§Ts?).
`If so (i.e., if both conditions are fulfilled at the same time and
`the alternative polling is answered with yes), spark angle
`retardation (Block 13) is activated for the next ignition z+1.
`The alternative polling (12) is continued until the number of
`ignitions Z is greater than the number of the parameter n.
`Starting from this moment in the operation, the alternative
`polling (Block 12) is thus answered with no, so that the spark
`angle retardation, which was activated up to this point
`(Block 13 with zén), is canceled by an appropriate advance-
`ment of the spark angle (Block 14). After this setting of the
`spark angle to normal (Block 14),
`the cold start angle
`adjustment is ended (Block 15).
`
`30
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`35
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`40
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`45
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`50
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`55
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`60
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`65
`
`4
`In the exemplary embodiment described with reference to
`the FIGURE, the retardation of the spark angle is set to a
`cold start value for a number of ignitions Z, which corre-
`sponds to the number of the parameter n. This spark angle
`retardation guarantees, or at least makes more probable, that
`the fuel or fuel-air mixture injected into the cylinder
`throughout the entire cold start phase is brought to combus-
`tion. Since the spark angle is retarded for
`the initial
`combustions, little or no torque is produced during the cold
`start, so that the increase in rotational speed is slight. As a
`result, a relatively long time may be available for all
`injections during the cold start phase, and, for example, for
`the second through the last injections (z>1 to z=n), to enable
`a sufficient quantity of fuel or fuel-air mixture for successful
`combustion to be injected into the respective cylinder. Thus,
`by retarding the spark angle, combustion misfirings during
`the cold start phase may be reliably prevented or reduced.
`Furthermore,
`the initial combustions in the respective
`cylinder produce a warming of the combustion chamber, for
`which reason the fuel or fuel-air mixture required to be
`injected into the respective cylinder to permit reliable com-
`bustion is reduced compared to a colder combustion cham-
`ber for the next ignition, so that the spark angle requires less
`retardation with increasing warming of the combustion
`chamber, due to the initial combustions during a cold start
`phase, to guarantee, or at least make more probable, suc-
`cessful combustion of the injected fuel or fuel-air mixture
`throughout the entire cold start phase. In this manner, the
`spark angle operating efficiency may be optimized during
`the cold start phase of an internal combustion engine, since,
`for each ignition in the cold start phase, the spark angle is
`retarded only as required for successful combustion at the
`time of all ignitions. This may prevent combustion misses.
`After a certain, individually adjustable number of igni-
`tions Z, the spark angle is set to normal, to limit the cold start
`phase to as few ignitions as possible and thus to operate the
`internal combustion engine at high spark angle operating
`efficiency with the largest possible spark angles (advanced
`ignition point) as quickly as possible. The spark angle
`retardation should apply to the first ignition during cold
`starting of a cylinder of the engine, to keep the duration of
`the start as short as possible. Aplurality of transitional steps
`may increase spark angle advancement in the transition from
`the spark angle retardation to the normal spark angle setting.
`The optimum retarded spark angle value (cold start value)
`may be calculated and individually set for each cylinder of
`the internal combustion engine.
`What is claimed is:
`
`1. A method of operating a spark ignition engine having
`at least one cylinder and a cold start phase,
`the method
`comprising:
`
`injecting a quantity of fuel into the at least one cylinder in
`the cold start phase, so that a time available for the
`injection of the quantity of fuel is insufficient at an
`elevated rotational speed of the spark ignition engine,
`wherein the cold start phase includes at least the first
`combustion upon start of the engine;
`retarding a spark angle in the cold start phase, so that a
`rotational speed of the spark ignition engine remains
`limited to a cold start value that is sufficient for the
`
`injection of the quantity of fuel during the cold start
`phase; and
`setting the spark angle to normal after the cold start phase.
`2. The method of claim 1, wherein the cold start phase
`includes at least the first two combustions upon start of the
`engine.
`
`EX. 2001 4/
`
`Ex. 2001 4/5
`
`

`
`US 6,725,835 B2
`
`5
`3. The method of claim 1, wherein the spark angle is set
`to normal in a single step to set a desired operating perfor-
`mance value.
`
`4. The method of claim 1, wherein the spark angle is set
`to normal in a plurality of transitional steps to set a desired
`operating performance value.
`5. The method of claim 1, wherein the cold start value is
`individually set for each of the at least one cylinder.
`6. The method of claim 1, wherein the cold start value is
`individually set during the cold start phase for a next 10
`combustion of a respective one of the at least one cylinder.
`
`6
`7. The method of claim 1, wherein the cold start value is
`set using a retardation adjusted to an operating temperature
`of a respective one of the at least one cylinder.
`8. The method of claim 7, wherein the retardation occurs
`if a number of ignitions is no greater than a value of a
`parameter, and a combustion chamber temperature before a
`first ignition is lower than a threshold temperature at a same
`time, the parameter being at least one and no greater than a
`number of cylinders of the at least one cylinder.
`
`EX. 2001 5/
`
`Ex. 2001 5/5