United States Patent [191
`Morikawa
`
`[11] Patent Number:
`[45] Date of Patent:
`
`5,050,551
`Sep. 24, 1991
`
`[54] SYSTEM FOR CONTROLLING IGNITION
`TIMING AND FUEL INJECTION TIMING OF
`A TWO-CYCLE ENGINE
`
`[75]
`
`Inventor: Koji Morikawa, Tokyo, Japan
`
`[73] Assignee: Fuji Jukogyo Kabushiki Kaisha,
`Tokyo, Japan
`
`[21] Appl. No.: 601,937
`
`[22] Filed:
`
`Oct. 22, 1990
`
`Foreign Application Priority Data
`[30]
`Nov. 22, 1989 [JP]
`Japan .................................. 1-306079
`
`Int. ct.s ......................... F02M 67/00; F02P 5/15
`[51]
`[52] u.s. ct ....................................... 123/305; 60/285;
`123/73 C; 123/425; 123/435
`[58] Field of Search ..................... 123/73 C, 295, 305,
`123/425, 435, 440, 489; 60/274, 276, 284, 285
`
`(56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`3,799,134 3/1974 Griese ................................. 123/407
`3,949,551 4/1976 Eichler et al. .................... 60/285 X
`4,111,010 9/1978 Minami ............................. 60/285 X
`4,165,610 8/1979 Iizuka et al. ...................... 60/285 X
`
`FOREIGN PATENT DOCUMENTS
`62-124211 8/1987 Japan .
`Primary Examiner-Tony M. Argenbright
`Attorney, Agent, or Firm-Martin A. Farber
`ABSTRACf
`(57]
`A temperature sensor is provided for detecting temper(cid:173)
`ature of exhaust gas in an exhaust passage of a two-cycle
`engine. The temperature is compared with a reference
`temperature for activating a catalytic converter. When
`the temperature is lower than the reference tempera(cid:173)
`ture, the ignition timing and the fuel injection timing of
`the engine are retarded. The quantity of injected fuel is
`increased so as to compensate reduction of engine
`power caused by retarding the ignition timing.
`
`3 Claims, 4 Drawing Sheets
`
`DETECT EXH~UST TEMPERATURE ls101
`
`NO
`
`DETERMINE RETARD QUANTITY
`
`S!03
`
`CORRECT INJECTION QUANTITY
`
`SI04
`
`DETERMINE INJECTION TIMING
`
`FUEL INJECTION
`
`SI05
`
`I
`SlOG I
`
`IGNITION
`
`SI07
`
`BOSCH-DAIMLER EXHIBIT 1011
`
`Page 1 of 8
`
`

`
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`
`DEPRESSING DEGREE SENSOR
`
`ACCELERATOR PEDAL
`
`32.!J CRANK ANGLE SENSOR
`
`CONTROL
`
`UNIT
`
`fIG. 1
`
`Page 2 of 8
`
`

`
`1-l
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`DRIVER
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`
`.ts
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`<51
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`DRIVER
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`t (52
`INJECTOR
`
`rr--
`~
`I
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`I
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`at I
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`
`I
`
`L ____________________________ J
`
`IGNITION TIMING
`
`DETERMINING
`
`SF:CTION
`
`COMPARATOR ~ DETERMINING r DETERMINING
`
`SECTION
`
`··-
`
`RETARD QUANTITY
`
`~42
`
`~41
`
`SECTION
`
`r43
`
`TIMING
`INJECTION
`
`4~
`CALCULATOR
`QUANTITY
`CORRECTING
`
`fl\O
`
`FUEL INJECTION
`
`CALCULATOR
`QUANTITY
`
`45-.
`
`1---
`ENGINE SPEED N
`
`CALCULATOR
`
`{4~
`
`47 ............
`
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`CRANK ANGLE e!
`I
`I
`l
`~!
`
`.
`
`33
`~
`
`SENSOR
`
`TEMPERATURE
`EXHAUST GAS
`
`(32
`
`SENSOR
`
`DEGREE SENSOR
`DEPRESSING
`ACCELERATOR
`
`PEDAL
`
`I
`
`I
`
`.------------------------1--..40
`
`31
`
`FIG. 2
`
`Page 3 of 8
`
`

`
`U.S. Patent
`
`Sep. 24, 1991
`
`Sheet 3 of 4
`
`5,050,551
`
`FIG.· 3
`
`START
`
`DETECT EXHAUST TEMPERATURE: -~5101
`
`NO
`
`DETERMINE RETARD QUAI'HITY
`
`5i03
`
`CORRECT INJECTION QUANTITY
`
`5104
`
`DETERMINE INJECTION TIMING
`
`5105
`
`FUEL INJECTION
`
`5106
`
`IGNITION
`
`5107
`
`Page 4 of 8
`
`

`
`U.S. Patent
`
`Sep. 24, 1991
`
`Sheet 4 of 4
`
`5,050,551
`
`ffG.4
`
`NORMAL
`
`BTDC
`
`TOC ATDC
`
`RET A2DED --+----+----+-----~.-
`
`~,
`
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`
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`Do
`f--f-(cid:173)u_
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`
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`0
`
`FIG. sa
`
`0
`a::
`c:::(
`f(cid:173)
`w
`a:: ~------~----------~---
`
`FIG. 5b
`
`r= I G. 5 c
`
`U1W
`c:::t:a::
`c..:J:::J
`1-
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`(/) a::
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`:::r:~ xw
`WI-
`
`RETARD
`
`IGNITION (NORMAL) ADVANCE
`TIMING
`
`Page 5 of 8
`
`

`
`SYSTEM FOR CONTROLLING IGNITION TIMING
`AND FUEL INJECTION TIMING OF A
`TWO-CYCLE ENGINE
`
`s
`
`30
`
`2
`retard quantity, correcting means for increasing the
`quantity of injected fuel in accordance with the retard
`quantity so as to compensate reduction of engine power
`caused by retarding the ignition timing.
`Since the ignition timing is retarded, the temperature
`of the exhaust gas increases, thereby activating the cata(cid:173)
`lytic converter. Thus, the control of the exhaust gas
`emission can be performed, even if the exhaust gas tem(cid:173)
`perature is lower than the temperature for activating
`the catalyst
`In an aspect of the invention, the reference tempera(cid:173)
`ture is a lower limit temperature for activating the cata(cid:173)
`lytic converter, and the retard quantity is set to increase
`with an increase of the difference between the detected
`temperature and the reference temperature.
`These and other objects and features of this invention
`will become understood from the following description
`with reference to the accompanying drawings.
`
`BRIEF DESCRIPTION OF DRAWINGS
`FIG. 1 is a schematic diagram of a two-cycle engine
`of the present invention;
`FIG. 2 is a block diagram showing a control unit
`according to the present invention;
`FIG. 3 is a flowchart showing operations of the sys(cid:173)
`tem;
`FIG. 4 is a time chart showing fuel injection and
`ignition timings; and
`FIGS. Sa to Sc are graphs showing variations of fuel
`injection, injection timing and exhaust gas temperature
`in accordance with the ignition timing.
`
`1
`
`5,050,551
`
`BACKGROUND OF THE INVENTION
`The present invention relates to a system for control(cid:173)
`ling ignition timing and fuel injection timing of a two(cid:173)
`cycle engine at cold state, and more particularly to a
`control system for the two-cycle engine having an ex- 10
`haust emission control system with a catalytic con(cid:173)
`verter.
`In a four-cycle engine, temperature of exhaust gas is
`high comparing with that of the two-cycle engine, so
`that a catalyst in the catalytic converter provided in an 15
`exhaust pipe is sufficiently heated to be activated for
`ensuring exhaust emission control.
`In the two-cycle engine, however, a part of intake air
`escapes from a cylinder through an exhaust port at
`scavenging the cylinder. Thus, the temperature of the 20
`exhaust gas is lowered. In particular, in a low engine
`speed range and a light load range, the catalyst is not
`heated to an activated temperature. As a result, the
`exhaust gas containing poisonous elements is emitted to
`atmosphere.
`In order to maintain the activated temperature of the
`catalyst, it is proposed to provide the catalytic con(cid:173)
`verter at an upper stream portion of the exhaust pipe so
`that the exhaust gas having a high temperature may pass
`through the catalytic converter.
`However, since the temperature of the exhaust gas is
`high in a full load range, durability and function of the
`catalyst are reduced.
`On the other hand, Japanese Utility Model Applica(cid:173)
`tion Laid-Open 62-124211 discloses a catalytic con- 35
`verter in which a heater is provided at an inlet thereof.
`The heater is adapted to change a heating value thereof
`in dependency on the temperature. It is effective to
`increase the temperature of the catalyst to the activated
`temperature. However, it consumes a large electric 40
`power, and it is difficult to heat the whole catalyst.
`Further, it is necessary to provide a control unit for
`heating the heater.
`
`25
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`Referring to FIG. 1, a two-cycle engine 1 comprises
`a cylinder 2, a piston 3 provided in the cylinder 2, a
`connecting rod 6 connected with the piston 3 and a
`crankshaft 5 disposed in a crankcase 4. A counterweight
`7 is mounted on the crankshaft 5 so as to reduce inertia
`of the piston 3 reciprocating in the cylinder 2.
`In a wall of the cylinder 2, an exhaust port 11 and a
`scavenge port 16 are formed in 90 degrees angular dis(cid:173)
`position or opposing one another. The ports 11 and 16
`are adapted to open at a predetermined timing with
`respect to a position of the piston 3.
`A fuel injector 10 and a spark plug 9 are provided on
`a top of a combustion chamber 8 of the cylinder 2. The
`injector 10 is a type where a predetermined amount ·of
`so fuel is directly injected in the cylinder and the quantity
`of the fuel is controlled with the injection pulse width.
`The fuel in a fuel tank 29 is supplied to the injector 10
`through a fuel passage 26 having a filter 28, a pump 27
`and a pressure regulator 30 for constantly maintaining
`the fuel at a predetermined fuel pressure.
`The engine 1 is supplied with air through an air
`cleaner 20, a displacement scavenge pump 19, and an
`intake pipe 17 having a scavenge chamber 18 for ab(cid:173)
`sorbing scavenge pressure waves when the scavenge
`port 16 is opened or closed. A bypass. 21 is provided
`around the scavenge pump 19. The bypass 21 is pro-
`vided with a control valve 22. Exhaust gas of the engine
`1 is discharged passing through the exhaust port 11, a
`rotary valve provided adjacent the exhaust port 11 in an
`exhaust pipe 13 having a catalytic converter 14 for
`controlling the exhaust gas emission, and a muffler 15.
`The scavenge pump 19 is operatively connected to
`the crankshaft 5 through a transmitting device 23 com-
`
`45
`
`SUMMARY OF THE INVENTION
`The object of the present invention is to provide an
`exhaust emission control system for a two-cycle engine
`in which temperature for activating a catalyst is main(cid:173)
`tained, thereby ensuring to control exhaust gas emis(cid:173)
`sion.
`According to the present invention, there is provided
`a system for controlling a two-cycle engine having at
`least one cylinder, a fuel injector provided for injecting'
`fuel directly in the cylinder, a spark plug for igniting the
`fuel, and a catalytic con vertex: in an exhaust passage for SS
`exhaust gas emission.
`The system comprises a temperature sensor for de(cid:173)
`tecting temperature of exhaust gas in the exhaust pas(cid:173)
`sage upstream of the catalytic converter, a comparator
`for comparing the temperature detected by the temper- 60
`ature sensor with a reference temperature for activating
`the catalytic converter and for producing a temperature
`signal when the detected temperature is lower than the
`reference temperature, retard quantity determining
`means responsive to the temperature signal for deter- 65
`mining a retard quantity for the ignition timing and fuel
`injection timing, retar.ding means for retarding the igni(cid:173)
`tion timing and the fuel injection timing based on the
`
`Page 6 of 8
`
`

`
`5,050,551
`
`20
`
`3
`prising an endless belt running over a crank pulley and
`a pump pulley. The scavenge pump 19 is driven by the
`crankshaft S through the transmitting device 23 for
`producing a scavenge pressure. An accelerator pedal 24
`is operatively connected with the control valve 22. An 5
`opening degree of the control valve 22 is controlled so
`as to be inversely proportional to the depressing degree
`of the accelerator pedal 24. Further, an accelerator
`pedal depressing degree sensor 31 and a crank angle
`sensor 32 are provided for determining engine operating 10
`conditions. An exhaust gas temperature sensor 33 is
`provided upstream of the catalytic converter 14 for
`detecting temperature of the exhaust gas. In addition, a
`pressure sensor 34 is provided in the fuel passage 26
`downstream of the pressure regulator 30 for detecting a 15
`pressure of the fuel to be injected.
`Output signals from the sensors 31, 32, 33 and 34 are
`supplied to a control unit 40 which feeds an ignition
`signal and a fuel injection pulse signal to the spark plug
`9 and the injector 10, respectively.
`Referring to FIG. 2, the control unit 40 comprises an
`engine speed calculator 46 to which a crank angle (J
`detected by the crank angle sensor 32 is applied for
`calculating engine speed N. The engine speed Nand an
`accelerator pedal depressing degree q, detected by the 25
`accelerator pedal depressing degree sensor 31 are ap(cid:173)
`plied to a fuel injection quantity calculator 47. The
`crank angle (J is further applied to an ignition timing
`determining section 43 and a fuel injection timing deter(cid:173)
`mining section 44, respectively.
`The control unit 40 is further provided with a com(cid:173)
`parator 41 to which an output signal of exhaust temper(cid:173)
`ature detected by the exhaust temperature sensor 33 is
`applied. In the comparator 41, a lower limit tempera(cid:173)
`ture for activating a catalyst in the catalytic converter 35
`14 is previously provided. The exhaust temperature is
`compared with the lower limit temperature. If the ex(cid:173)
`haust temperature is lower than the lower limit temper(cid:173)
`ature, the comparator 41 produces an output signal
`which is applied to an ignition/injection timing retard 40
`quantity determining section 42. In the section 42, quan(cid:173)
`tity for retarding the ignition timing and for retarding
`the fuel injection timing are determined. The retard
`quantity is determined in accordance. with the differ(cid:173)
`ence between the exhaust temperature and the lower 45
`limit temperature. If the difference is large, the retard
`quantity becomes large. However, the maximum retard
`value is determined. The retard quantity is applied to
`the ignition timing determining section 43 in which an
`ignition timing ts is determined. The ignition timing ts is 50
`applied to the spark plug 9 through a driver 51. The
`retard quantity is also applied to the fuel injection tim-
`ing determining section 44 in which a fuel injection
`timing ti is determined. The fuel injection timing ti is
`applied to the injector 10 through a driver 52.
`Since the ignition timing is retarded, the power of the
`engine is reduced. In order to compensate the reduction
`of the engine power, the quantity of fuel injected from
`the injector 10 is increased. To this end, the control unit
`40 is provided with a correcting injection quantity cal- 60
`culator 45 to which the retard quantity determined in
`the section 42 is applied for calculating a correcting
`injection quantity ~Q. The correcting injection quan(cid:173)
`tity ~Q is applied to the fuel injection quantity calcula(cid:173)
`tor 47 where a corrected fuel injection quantity Qf is 65
`calculated. The fuel injection quantity Qf is applied to
`the fuel injector 10 through the driver 52 at the retarded
`injection timing ti.
`
`4
`The operation of the system will be described herein
`after with reference to the flowchart of FIG. 3.
`When the engine starts, the temperature of the ex(cid:173)
`haust gas is detected at a step SlOt. At a step S102, the
`exhaust gas temperature is compared with the predeter(cid:173)
`mined lower limit temperature of the temperature of the
`activated catalyst. If the exhaust gas temperature is
`lower than the lower limit, the program goes to a step
`S103. If not, the program returns to step SlOt.
`At the step S103, the retard quantity of the ignition
`timing and the fuel injection timing is determined. At a
`step S104, the fuel injection quantity is corrected based
`on the retard quantity. At a step SlOS, the fuel injection
`timing is determined. At a step S106, a predetermined
`increased quantity of fuel is injected from the injector
`10. At a step S107, ignition is performed by the spark
`plug 9.
`In a normal engine operation, the fuel injection tim(cid:173)
`ing ti and ignition timing ts are determined at a proper
`interval before top dead center as shown in FIG. 4, so
`that charge stratification may be performed in the com(cid:173)
`bustion. When the exhaust gas temperature is lower
`than the lower limit of the temperature of the activated
`catalyst, the timings ts and ti are retarded. The timings
`ts and ti are determined at a proper interval after top
`dead center. When the exhaust gas temperature rises
`and exceeds the lower limit temperature, the correcting
`operation to retard the timings is cancelled and the
`30 correcting operation to increase the fuel injection quan(cid:173)
`tity is stopped.
`FIG. 5 shows variations of the fuel injection quantity,
`fuel injection timing and exhaust temperature corre(cid:173)
`sponding to the ignition timing.
`Although the exhaust gas temperature is detected in
`the above described embodiment of the present inven(cid:173)
`tion, temperature of the catalyst may be detected in
`stead of the exhaust gas temperature.
`In accordance with the present invention, since the
`ignition timing is retarded, the temperature of the ex(cid:173)
`haust gas is increased, thereby activating the catalyst in
`the catalytic converter. Thus, the control of the exhaust
`emission can be performed, even if the exhaust gas tem(cid:173)
`perature is lower than the temperature for activating
`the catalyst.
`The fuel injection quantity is increased when the
`ignition timing is retarded, so that the power of the
`engine is prevented from reducing. Since the quantity
`for retarding the ignition timing is determined in accor(cid:173)
`dance with the lower limit of the temperature for acti(cid:173)
`vating the catalyst, the increase of the fuel consumption
`caused by an excess of retardation is avoided.
`While the presently preferred embodiment of the
`present invention has been shown and described, it is to
`55 be understood that this disclosure is for the purpose of
`illustration and that various changes and modifications
`may be made without departing from the scope of the
`invention as set forth in the appended claims.
`What is claimed is:
`1. A system for controlling a two-cycle engine having
`at least one cylinder, a fuel injector provided for inject(cid:173)
`ing fuel directly in the cylinder, a spark plug for igniting
`the air fuel mixture, and a catalytic converter in an
`exhaust passage for exhaust gas emission, the system
`comprising:
`a temperature sensor for detecting temperature of
`exhaust gas in the exhaust passage upstream of said
`catalytic converter;
`
`Page 7 of 8
`
`

`
`5
`a comparator for comparing the temperature with a
`reference temperature for activating said catalytic
`converter and for producing a temperature signal
`when the temperature is lower than the reference
`temperature;
`retard quantity determining means responsive to said
`temperature signal for determining a retard quan(cid:173)
`tity for the ignition timing and fuel injection tim(cid:173)
`ing;
`retarding means for retarding the ignition timing and 10
`the fuel injection timing based on said retard quan(cid:173)
`tity; and
`
`5
`
`5,050,551
`
`6
`correcting means for increasing quantity of injected
`fuel in accordance with said retard quantity so as to
`compensate reduction of engine power caused by
`retarding the ignition timing.
`2. The system according to claim 1, wherein
`said reference temperature is a lower limit tempera(cid:173)
`ture for activating the catalytic converter.
`3. The system according to claim 1, wherein
`said retard quantity is set to increase with an increase
`of the difference between the temperature and said
`reference temperature.
`* * * * *
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`Page 8 of 8