United States Patent
`
`[19]
`[11]
`6,047,679
`[45]
`Matsumoto et al.
`Date of Patent:
`Apr. 11, 2000
`
`Patent Number:
`
`USOO6047679A
`
`[54] CONTROL APPARATUS FOR AN INTERNAL
`COMBUSTION ENGINE
`
`[75]
`
`Inventors: Takuya Matsumoto, Okazaki; T0ru
`Hashimoto, Toyoake; Mitsuhiro
`Miyake, Kyoto; Seiichi Inoue,
`Okazaki, all Of Japan
`[73] Assignee' Mitsubishi Jidosha Kogyo Kabushiki
`. Kaisha Tokyo Japan
`’
`’
`[21] Appl. No.: 09/061,185
`.
`[22]
`Apr. 17’ 1998
`Flled’
`[30]
`Foreign Application Priority Data
`9123431
`Apr 25 1997
`[JP]
`Japan
`Apr. 25: 1997
`[JP]
`Japan .................................... 9—123432
`[51]
`Int Cl 7
`F02D 1/00
`[52] U S Cl
`"""""""""""""""""""""""""123/396' 123/399
`
`..
`[58] Field 0f Search
`123f361 399
`................................
`12,3/396’
`
`[56]
`
`References Cited
`
`U S PATENT DOCUMENTS
`.
`3,323,223 13133:
`giggfiicmhil: :i‘ai““““““““““““ 3:333
`
`5:490:071
`2/1996 Akabane ........ .
`123/396
`
`..
`.. 123/399
`5,727,523
`3/1998 Suzuki et a1.
`
`5/1998 NlChOIS 6t al~
`-~ 123/396
`577497343
`
`" 3:332
`:gg’ig: 13133:
`Jstisiseftalil.
`...............................
`,
`,
`.
`FOREIGN PATENT DOCUMENTS
`
`Primary Examiner—John Kwon
`Attorney, Agent, or Firm—Birch, Stewart, Kolasch & Birch,
`LLP
`
`[57]
`
`ABSTRACT
`
`A control apparatus for an internal combustion engine is
`applied to vehicles equipped With a so-called drive by Wire.
`When one of several control systems Within the control
`apparatus fails, the drive is urged to obtain repairs. Also,
`even When all of the several control systems of the drive by
`Wire fail and the failures of these control systems cannot be
`detected, unpredictable motion of the throttle valve can be
`prevented, thereby enhancing vehicle safety. The present
`invention includes a plurality of electronic throttle control
`Systems for electrically driVng a throttle ValVe of an internal
`combustion engine, a failure detecting mechanism for
`detecting failures of the electronic throttle control systems,
`intake air volume control mechanism for driving the throttle
`valve in a closing direction and also supplying a predeter-
`mined intake air volume to the internal combustion engine
`if it is judged that all electronic throttle control systems have
`
`failed, and output suppression mechanism for controlling the
`driving of the throttle valve by a normal electronic throttle
`control system and also suppressing output of the internal
`combustion engine corresponding to the operational quan-
`tity of the accelerator pedal if the failure determining mecha-
`nism determines that one electronic throttle control system
`among the several electronic throttle control systems has
`failed.
`
`1—92553
`
`4/1989
`
`Japan .
`
`16 Claims, 6 Drawing Sheets
`
`15:THROTTLE
`
`154,M0T0R
`155
`
`VALVE
`
`151
`_.
`
`7"
`
`37B (TPSE‘)
`
`61
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`SUPPLY RELAY
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`£333“ 12°
`Q
`16A
`
`_.
`
`..J
`
`CONTROLLER
`16-.ENGINE COMPUTER i:
`
`470
`CHECK LAMP
`NIH/180
`-> ENGINE
`CHE
`// I
`1 \\ \
`RITA:
`
`
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`12= LAMP HOME VALVE \ ,1
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`14
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`51A (APSI )
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`5OIACCEL PEDAL
`
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`AUTOMATIC CRUISING
`
`.
`
`RELATED INPUT AUTOMATIC CRUISE CONTROL
`
`I COMMUNICATION
`THROTTLE OPENING ANGLE FEEDBACK CONTROL
`ACTUATOR DISOONNECTION /SHORT-C| CUIT DETECTION
`(FAILURE JUDGMENT MEANS) (CIRCUIT
`ENGINE COMPUTER MONITORING
`
`160A
`
`70
`
`‘IGOITHROTTLE CONTROLLER
`
`VW EX1012
`
`US. Patent No. 6,588,260
`
`VW EX1012
`U.S. Patent No. 6,588,260
`
`

`

`US. Patent
`
`Apr. 11, 2000
`
`Sheet 1 0f 6
`
`6,047,679
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`

`US. Patent
`
`Apr. 11,2000
`
`Sheet 2 0f 6
`
`6,047,679
`
`ENGINE ECU
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`
`50
`
`
`
`
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`//51AIAPSI)
`
`

`

`US. Patent
`
`6
`
`6,047,679
`
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`

`US. Patent
`
`Apr. 11,2000
`
`Sheet 4 0f 6
`
`6,047,679
`
`FIG. 4
`
`START
`
`LHV FAILURE JUDGMENT ROUTINE
`
`A10
`A20
`
`YES
`
`6A4YES
`
`FfoIII=1?
`
`A30
`
`536"“ 3&7? R00 33
`PPRE
`I
`P
`E
`
`APs FAILURE JUDGMENT ROUTINE
`
`A50
`
`YES
`APS FAILURE ?
`A70
`NO
`A60
`ETV FAILURE JUDGMENT ROUTINE
`
`FfaIII=1
`
`“536
`
`9
`
`DUAL FAILUREO0F APS :2
`No
`BRAKE SWITCHN0N ?
`ETV FAILURE ?
`6 YES
`A140
`PROCESS
`
`DURING
`
`LIMIT OF AN ACCEL OPENING
`FAILURE
`ANGLE INSTRUCTION VALUE
`
`COMMUNICATIONoFAILURE ? YES
`A100
`A180
`RETURN
`MOTOR FAILURE JUDGMENT ROUTINE
`
`COMMUNICATION FAILURE
`
`PROCESS OF CLIPPING AN UPPER
`
`JUDGMENT ROUTINE
`
`A120
`
`A130
`
`A150
`A160
`
`A200
`
`A210
`
`G
`
`YES—NO COMMUNICATION FAILURE
`MOTOR FA'LURE "
`A170 CORRESPONDING'PROCESS
`
`A190
`
`RETURN
`
`TPS FAILURE JUDGMENT ROUTINE
`YES
`
`
`TPS1 OR TPsz FAILURE ?
`NO
`
`-
`TPS1 AND TPSZ FAILURE ?
`
`YES
`
`
`LEAN MODE INHIBITING
`PROCESS
`
`A240 No
`
`
`
`
`
`LIMP HOME
`CLOSED-VALVE STICKING
`OPENED-VALVE STICKING
`IFAILURE PROCESS
`I FAILURE PROCESS
`I PROCESS
`
`
`A280
`
`A290
`
`A300
`
`

`

`US. Patent
`
`Apr. 11,2000
`
`Sheet 5 0f 6
`
`6,047,679
`
`FIG. 5
`
`'LIMP HOME PROCESS ROUTINE I
`
`310
`
`LEAN MODE INHIBITION
`
`820
`
`MOTOR RELAY OFF
`
`830
`
`B40
`
`860
`
`870
`
`NO
`BRAKE SWITCH ON ?
`
`
`
`LHV DUTY CONTROL (50%)
`
`850
`
`FORWARD MOVEMENT ?
`
`NOIREVERSE MOVEMENT)
`
`
`YES (FORWARD MOVEMENT)
`
`
`
`NO
`
`
`
`5-V AP52>1.5 ?
`
`880 “
`
`AP82 FAILURE ?
`
`B100
`
`BRAKE SWITCH ON ?
`
`
`ALL-CYLINDER FUEL INJECTION
`3-CYLINDER FUEL CUT
`
`
`
`BI1O
`
`RETURN
`
`

`

`US. Patent
`
`Apr. 11, 2000
`
`Sheet 6 0f 6
`
`6,047,679
`
`NF
`
`5N
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`

`

`6,047,679
`
`1
`CONTROL APPARATUS FOR AN INTERNAL
`COMBUSTION ENGINE
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`The present invention relates to a control apparatus for an
`internal combustion engine which is applied to vehicles
`equipped with an electronic throttle control unit which
`electrically drives a throttle valve, called a drive by wire
`(DBW).
`2. Description of Related Art
`In engines such as automobile engines, a drive by wire
`(hereinafter referred to as a DBW) connecting an accelerator
`pedal (hereinafter referred to as an accel pedal) and a throttle
`valve together by an electrical signal has hitherto been
`developed. In a DBW such as this, the accel pedal and the
`throttle valve are not mechanically connected, and based on
`a variety of parameters in addition to an operational quantity
`of the accel pedal (accel opening angle), a virtual accel
`opening angle (“pseudo” accel opening angle) is set by a
`computer. Based on this, the throttle valve can be controlled,
`and the DBW is also referred to as an electronic throttle
`control unit.
`
`Therefore, for example, during idling where the accel
`pedal has not been operated (i.e., the accel opening angle is
`less than a small predetermined value), idling engine speed
`can be controlled, while the throttle valve is adjusted with
`fine precision. Also, in accordance with the traveling state of
`the vehicle and the operating state of the engine, the accel
`opening angle (driver’s operation) is corrected in order to set
`a pseudo accel opening angle. With the control of the throttle
`valve based on this, engine running with a feeling of
`smoothness is realizable.
`
`On the other hand, a spark ignition type in-cylinder
`injection internal combustion engine (hereinafter referred to
`as an engine), which is an internal combustion engine that
`uses sparks by spark plugs to ignite fuel (generally, a
`gasoline engine) that injects fuel directly into cylinders, has
`been put to practical use in recent years. In such an engine,
`an enhancement
`in the engine fuel consumption perfor-
`mance and an enhancement in the output performance are
`compatible with each other by making use of the character-
`istic that fuel injection timing can be freely performed and
`also the formed state of an air-fuel mixture can be freely
`controlled.
`
`in this spark ignition type in-cylinder
`In other words,
`injection engine, fuel is injected on the compression stroke,
`and with this, an operation in a state in which fuel
`is
`extremely lean (i.e., a super-lean combustion operation in
`which an air-fuel ratio is extremely higher than a stoichio-
`metric air-fuel ratio) can be performed by stratified-charge
`combustion. The engine is provided with a super lean
`operating mode (compression stroke injection mode or lean
`compression operating mode) as the combustion form and
`can realize a considerable enhancement in the fuel consump-
`tion ratio.
`
`Of course, the spark ignition type in-cylinder injection
`engine can also perform a premixed combustion operation in
`which fuel is injected primarily on the intake stroke. In this
`case, fuel is injected directly into the combustion chamber
`(cylinder), whereby the greater part of fuel injected at each
`combustion cycle can be burned with reliability within the
`combustion cycle. The engine, therefore, can also enhance
`the engine output.
`Apremixed combustion operation such as this can also set
`as combustion form a lean operating mode (lean intake
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`
`operating mode) which performs operation in a fuel-leaned
`state which is not as lean as the super lean operating mode
`(i.e., in a state in which an air-fuel ratio is higher than a
`stoichiometric air-fuel ratio), a stoichiometric operating
`mode (stoichiometric feedback operating mode) which per-
`forms feedback control on the basis of Oz-sensor informa-
`tion so that an air-fuel ratio reaches a stoichiometric air-fuel
`
`ratio, and an enriched operating mode (open-loop operating
`mode) which performs operation in a fuel-enriched state
`(i.e., in a state in which an air-fuel ratio is lower than a
`stoichiometric air-fuel ratio).
`In general, if a requested output to the engine is small, i.e.,
`if the revolution speed of the engine is low and also the
`engine load is low, the lean compression operating mode
`will be selected in order to enhance fuel consumption. As the
`engine revolution speed and the engine load increase further,
`the lean intake operating mode, the stoichiometric operating
`mode, and the enriched operating mode are selected in the
`recited order.
`
`in the case of the super lean combustion
`Incidentally,
`operating mode (lean compression operating mode), there is
`a need to supply more air to the combustion chamber in
`order to make an air-fuel ratio high. However, in this lean
`compression operating mode, since operation is performed
`when engine load is low, i.e., when the stepping-on quantity
`of the accel pedal (accel opening angle) is small, the opening
`angle of the throttle valve corresponding to the accel open-
`ing angle cannot satisfy a required air-fuel ratio.
`Hence, a technique where an electronically controlled
`valve (air bypass valve) is arranged in an air bypass passage
`bypassing an intake-air passage equipped with the throttle
`valve has been developed. In this technique, when intake air
`is insufficient at
`the opening angle of the throttle valve
`corresponding to the accel opening angle,
`the air bypass
`valve is opened based on a required air volume, thereby
`performing air supply.
`Incidentally, applying the aforementioned DBW to the
`above-mentioned spark ignition type in-cylinder injection
`engine is also considered. In other words, in the DBW, since
`the opening angle of the throttle valve can be controlled
`without corresponding to the accel opening angle, more air
`than a quantity corresponding to the accel opening angle can
`be supplied to the combustion chamber. Therefore, for
`example, in the lean compression operating mode of the
`spark ignition type incylinder injection engine, even if the
`accel opening angle is small, a necessary quantity of air can
`be supplied to the combustion chamber.
`In the case where such a DBW is adopted, it is desirable
`to prepare a counter plan against an unlikely failure of the
`DBW as well.
`
`For instance, to achieve such a counter plan several sets
`of sensors are provided in the DBW, such as accel position
`sensors (APSs) and throttle position sensors (TPSs), and a
`plurality of sets of actuators for driving a throttle valve.
`That is, two sets of sensors and two sets of actuators (these
`will hereinafter be referred together to as two sets of control
`systems) are provided, and if one control system fails, the
`DBW will be controlled by the other of the control system.
`The DBW is provided with a fail safe system by providing
`such a duplex control system, whereby safety and durability
`of the DBW can be enhanced.
`
`Incidentally, in the above-mentioned dual control system
`of the DBW, when one control system has failed, a warning
`lamp within the instrument panel, for example, is lit, thereby
`informing the driver of an abnormality in the sensor or
`urging the driver to repair.
`
`

`

`6,047,679
`
`3
`However, the driver may continue to travel without notic-
`ing a warning such as this. Also, even if the driver is aware
`of a warning such as this, the driver may continue to travel
`based on the knowledge that the DBW is equipped with a
`fail safe system such as this, the DBW is controlled by the
`other normal control system and has no adverse effect on the
`traveling performance.
`However, if the driver continues to travel with one control
`system failed and, thereafter, the other control system fails,
`there is a problem that usual traveling will be difficult.
`Note that although Japanese Laid-Open Patent Publica-
`tion No. SHO 64-92553 discloses a technique which can
`ensure vehicle safety when an accel pedal fails, the disclosed
`technique is not one which solves the above-mentioned
`problems.
`In addition, in the case where all of the above-mentioned
`plurality of control systems have failed, if the failures of the
`control systems should not be detected for some reasons,
`unpredictable motion of the throttle valve may occur.
`Hence, even in the case where all of a plurality of control
`systems fail and also these failures cannot be detected, there
`is a desired demand for some counter plan to be prepared for
`safety.
`
`SUMMARY OF THE INVENTION
`
`The present invention has been made in view of the
`above-mentioned problems. An object of the present inven-
`tion is to provide a control apparatus for an internal com-
`bustion engine where, when one control system among a
`plurality of control systems fails in a vehicle equipped with
`an electronic throttle control unit (drive by wire), the driver
`is caused to feel the failure of the control system and urged
`to repair. Another object of the present
`invention is to
`provide a control apparatus for an internal combustion
`engine which prevents unpredictable motion of the throttle
`valve and enhances vehicle safety, even when all of a
`plurality of control systems of the drive by wire fail and also
`the failures of these control systems cannot be detected.
`To achieve the aforementioned objects of the present
`invention, a control apparatus for an internal combustion
`engine according to the present
`invention comprises: a
`plurality of electronic throttle control systems for electri-
`cally driving a throttle valve of the internal combustion
`engine on the basis of an operational quantity of an accel
`pedal; failure judgment means for judging failure states of
`the plurality of electronic throttle control systems, the failure
`judgment means being constituted so that failures of the
`plurality of electronic throttle control systems can be judged
`individually; intake air volume control means for driving the
`throttle valve in a closing direction and also supplying a
`predetermined intake air volume to the internal combustion
`engine, in the case where it is judged by the failure judgment
`means that all electronic throttle control systems have failed;
`and output suppression means for controlling the driving of
`the throttle valve by a normal electronic throttle control
`system and also suppressing output of the internal combus-
`tion engine corresponding to the operational quantity of the
`accel pedal, in the case where it is judged by the failure
`judgment means that one electronic throttle control system
`of among the plurality of electronic throttle control systems
`has failed.
`
`According to such constitution, if a failure of one elec-
`tronic throttle control system of among a plurality of elec-
`tronic throttle control systems is detected by the failure
`judgment means, the throttle valve is driven by a normal
`electronic throttle control system and also the output of the
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`internal combustion engine corresponding to the operational
`quantity of the accel pedal is suppressed by the output
`suppression means. Therefore,
`there is an advantage of
`being able to cause the driver to recognize with reliability
`the failure of one electronic throttle control system.
`In
`addition, even in the case the driver continues to travel
`recognizing a failure of one electronic throttle control
`system, engine output is suppressed. Therefore, it is possible
`to cause the driver to recognize the necessity of repair, and
`safety is enhanced.
`is judged by the failure
`Also,
`in the case where it
`judgment means that all electronic throttle control systems
`have failed, the intake air volume control means drives the
`throttle valve in a closing direction and also supplies a
`predetermined intake air volume to the engine.
`It is preferable that the output suppression means reduce
`the degree of change of the throttle valve with respect to the
`operational quantity of the accel pedal of the driver.
`In addition to the above-mentioned constitution, the elec-
`tronic throttle control system may be constituted by accel
`opening angle detection means for detecting the operational
`quantity of the accel pedal, an actuator for opening or
`closing the throttle valve on the basis of a result of the
`detection of the accel opening angle detection means, and
`throttle opening angle detection means for detecting an
`opening angle of the throttle valve.
`At least one of among the accel opening angle detection
`means, the actuator, and the throttle opening angle detection
`means may be provided respectively in the plurality of
`electronic throttle control systems.
`the electronic throttle
`According to such constitution,
`control system is constituted by the accel opening angle
`detection means,
`the actuator for opening or closing the
`throttle valve, and the throttle opening angle detection
`means. At
`least one of among the accel opening angle
`detection means, the actuator, and the throttle opening angle
`detection means is provided respectively in the electronic
`throttle control systems. Therefore, a fail safe system for the
`electronic throttle control unit can be provided, whereby
`safety and reliability of the electronic throttle control unit
`can be enhanced.
`
`The control apparatus according to the present invention
`may further comprise: a brake switch for detecting an
`operating state of a brake; and regulation means for regu-
`lating an upper limit of the opening angle of the throttle
`valve, if a failure of one electronic throttle control system of
`among the plurality of electronic throttle control systems is
`judged by the failure judgment means and also if the
`operation of the brake is detected by the brake switch.
`According to such constitution, in the case where a failure
`of one electronic throttle control system of among a plurality
`of electronic throttle control systems is judged by the failure
`judgment means and also the operation of the brake is
`detected by the brake switch, the upper limit of the opening
`angle of the throttle valve is regulated by the regulation
`means. Therefore, thereafter, even in the case where failure
`judgment is not made although the other electronic throttle
`control system has failed, unpredictable motion of the
`throttle valve can be prevented, and there is an advantage of
`being able to enhance vehicle safety.
`Also, even if the other electronic throttle control system
`is normal, when one electronic throttle control system fails,
`the upper limit value of the opening degree of the throttle
`valve is clipped if the operation of the brake is detected.
`Therefore, the driver is caused to recognize an abnormality
`in the vehicle by the change in the engine output, and there
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`is an advantage of urging the driver to an early repair of the
`vehicle. With this, there is another advantage of enhancing
`reliability and safety of the electronic throttle control unit.
`Preferably,
`in addition to the above-mentioned
`constitution, the plurality of electronic throttle control sys-
`tems include at
`least
`the accel opening angle detection
`means for detecting the operational quantity of the accel
`pedal, respectively. Also, the failure judgment means judges
`failures of the electronic throttle control systems on the basis
`of a difference in detection information between the plurality
`of accel opening angle detection means.
`According to such constitution, even in the case where
`dual failure of the accel opening angle detection means is not
`judged although it has occurred, unpredictable motion of the
`throttle valve can be prevented with reliability and there is
`also an advantage of being able to enhance vehicle safety.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The present invention will be described in further detail
`with reference to the accompanying drawings wherein:
`FIG. 1 is a schematic constitution diagram showing the
`essential parts of a control apparatus for an internal com-
`bustion engine according to an embodiment of the present
`invention;
`FIG. 2 is a block diagram showing the control apparatus
`for an internal combustion engine according to the embodi-
`ment of the present invention;
`FIG. 3 is a block diagram showing the intake control
`system of the internal combustion engine according to the
`embodiment of the present invention;
`FIG. 4 is a flowchart showing the failure counter plan
`process of the intake control system of the internal combus-
`tion engine according to the embodiment of the present
`invention;
`FIG. 5 is a flowchart showing a limp home process in the
`failure counter plan process of the intake control system of
`the internal combustion engine according to the embodiment
`of the present invention; and
`FIG. 6 is a schematic block diagram giving attention to
`the essential functions of the control apparatus for an
`internal combustion engine according to the embodiment of
`the present invention.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`If a description will hereinafter be made of an embodi-
`ment of the present invention, FIGS. 1 through 6 show an
`in-cylinder injection internal combustion engine to which a
`control apparatus for an internal combustion engine as an
`embodiment of the present invention is applied, and the
`embodiment will be described based on these figures.
`
`General Description of an In-cylinder Injection
`Internal Combustion Engine
`
`First, a description will be made of the constitution of a
`spark-ignition type in-cylinder injection internal combustion
`engine (hereinafter also called an in-cylinder injection inter-
`nal combustion engine) in reference to FIG. 2.
`In FIG. 2, 1 is an engine main body, 2 an intake passage,
`3 a throttle valve installation portion, and 4 an air cleaner.
`The intake passage 2 is constituted by an intake pipe 7, a
`throttle body 5, a surge tank 8, and an intake manifold 9,
`connected in this order from the upstream side.
`The throttle body 5 is equipped with an electronically
`controlled throttle value (intake air volume regulation
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`means) 15. An opening angle of the electronically controlled
`throttle value 15 is controlled through a throttle control
`computer (throttle controller) 160 to be described later. A
`target opening angle of the -throttle valve (target throttle
`opening angle) is set according to a stepping-on quantity of
`an accel pedal 50 (accel opening angle) detected with an
`accel position sensor (TPS1) 51A and an operating state of
`the engine by an engine control computer (ECU) 16 to be
`described later.
`
`The electronically controlled throttle value 15, the ECU
`16, and the throttle controller constitute an electronic throttle
`control unit (i.e., a drive by wire (DBW)) 150.
`Also, a limp home valve (LHV) 12 is arranged parallel
`with the electronically controlled throttle value 15. This
`LHV 12 supplies air so that combustion of the engine is
`established when the electronically controlled throttle valve
`15 has failed (when closed-valve failure has occurred). This
`failure will be described later. The LHV 12 is constituted by
`a bypass passage 13 provided on the upstream side of the
`surge tank 8 so that it bypasses the electronically controlled
`throttle value 15, and an LHV main body 14 arranged in this
`bypass passage 13. The LHV main body 14 is driven with a
`linear solenoid (not shown) which is controlled by the
`engine control computer (ECU) 16 to be described later.
`Also, 17 is an eXhaust passage and 18 a combustion
`chamber. The opening of the intake passage 2 to the com-
`bustion chamber 18 and the opening of the eXhaust passage
`17 to the combustion chamber 18, i.e., an intake port 2A and
`an eXhaust port 17A are provided with an intake valve 19
`and an eXhaust valve 20, respectively. Furthermore, 21 is a
`fuel
`injection valve (injector).
`In this embodiment,
`the
`injector 21 is arranged so as to inject fuel directly into the
`combustion chamber 18.
`
`In addition, 22 is a fuel tank, 23A through 23E fuel supply
`paths, 24 a low-pressure fuel pump, 25 a high-pressure fuel
`pump, 26 a low-pressure regulator, 27 a high-pressure
`regulator, and 28 a delivery pipe. Fuel within the fuel tank
`22 is supplied by the low-pressure fuel pump 24.
`Furthermore, the fuel is pressurized with the high-pressure
`fuel pump 25 and supplied in a predetermined high-pressure
`state to the injector 21 through the fuel supply paths 23A and
`23B and the delivery pipe 28. At this time, the fuel pressure
`discharged from the low-pressure fuel pump 24 is regulated
`with the low-pressure regulator 26. The fuel pressure, pres-
`surized with the high-pressure fuel pump 25 and guided to
`the delivery pipe 28,
`is regulated with the high-pressure
`regulator 27.
`Additionally, 29 is an eXhaust gas recirculation passage
`(EGR passage) which recirculates a portion of the eXhaust
`gas into the intake passage 2. 30 is an EGR valve (exhaust
`gas volume regulation means), which regulates the recircu-
`lation volume of the eXhaust gas that is recirculated into the
`intake passage 2 through the EGR passage 29. 32 is a
`passage for restoring blow-by gas, 33 a valve for positively
`ventilating the crank chamber, 34 a canister, and 35 a
`catalyzer for purifying eXhaust gas (here, catalytic converter
`rhodium (CCRO)).
`Incidentally, as shown in FIG. 2, the ECU 16 performs the
`control of the LHV 12 in accordance with an operating state
`or failed state of the engine in addition to the drive control
`of the injector 21, the drive control of the spark wire coils
`(not shown) which operate spark plugs, the opening angle
`control of the EGR valve, and the combustion pressure
`control by the high-pressure regulator 27. The throttle con-
`troller 160 also performs the opening and closing control of
`the electronically controlled throttle value 15 in accordance
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`6,047,679
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`7
`with the accel instruction of the driver or an operating state
`or failed state of the engine.
`to the ECU 16 detection
`Hence, as shown in FIG. 2,
`signals are transmitted from a first accel position sensor
`(APS1) 51A, an air flow sensor (not shown), an intake-air
`temperature sensor 36, a throttle position sensor (TPS2) 37B
`for detecting a throttle opening angle, an idle switch 38, a
`boost sensor (not shown), an air-con switch (not shown), a
`shift position sensor (not shown), a wheel speed sensor (not
`shown), a power steering wheel switch (not shown) for
`detecting an operating state of a power steering wheel, a
`starter switch (not shown), a first-cylinder sensor 40, a crank
`angle sensor 41, a water temperature sensor 42 for detecting
`temperature of engine cooling water, an 02 sensor 43 for
`detecting oxygen concentration in exhaust gas, etc. Note that
`since the revolution speed of the engine can be computed
`based on the crank angle sensor 41, the crank angle sensor
`41 is also called an engine revolution speed sensor for
`convenience sake.
`
`In addition, as shown in FIG. 2, to the throttle controller
`160 detection signals are transmitted from an accel position
`sensor (APS2) 51B, a throttle position sensor (TPS1) 37A,
`etc.
`The ECU 16 and the throttle controller 160 are constituted
`
`information can be exchanged therebetween by
`so that
`communication.
`
`Furthermore, this engine is provided with an automatic
`transmission (AT) 170 and an automatic transmission con-
`troller (AT controller) 171 for controlling the automatic
`transmission 170. Similarly, the ECU 16 and the AT con-
`troller 171 are constituted so that
`information can be
`
`exchanged therebetween by communication.
`This engine is also equipped with an automatic cruise
`function, and according to input information relevant to
`automatic cruising, the throttle opening angle control by the
`throttle controller 160 is performed.
`Such an engine, incidentally, has as operating modes a late
`lean combustion operating mode (compression stroke injec-
`tion mode), an early lean combustion operating mode, a
`stoichiometric feedback operating mode, and an open-loop
`combustion operating mode. Any of these modes is selected
`according to an operating state of the engine (i.e., engine
`revolution speed and engine load) or a traveling state of the
`vehicle.
`
`Among these modes, the late lean combustion operating
`mode is a mode in which fuel injection is performed in a
`stage extremely near ignition timing as in the latter period of
`the compression stroke and also stratified-charge combus-
`tion is performed by collecting fuel near the spark plug in
`such a manner that the air-fuel ratio is partially rich and lean
`as a whole. The late leans combustion operating mode is also
`a super-lean combustion mode in which economical opera-
`tion can be performed ensuring ignitability and combustion
`stability. Although this embodiment sets the total air-fuel
`ratio to an area of about 24 or higher and can realize the
`leanest combustion, the total air-fuel ratio may be set to a
`lower area than this embodiment (e.g., a range in which the
`total air-fuel ratio is about 23 or higher) or may be set to a
`higher area than this embodiment.
`Although the early lean combustion operating mode is
`also a lean combustion mode,
`this mode performs fuel
`injection (primarily on the intake stroke) before the late lean
`combustion operating mode. The early lean combustion
`operating mode is a mode in which economical operation is
`performed by premixing air and fuel so that ignitability and
`combustion stability are ensured and also a certain degree of
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`output is obtained, while causing the air-fuel ratio to be
`leaner as a whole than a stoichiometric air-fuel ratio. The
`
`area of the early lean combustion operating mode here is set
`to an area where the total air-fuel
`ratio is between a
`stoichiometric air-fuel ratio and about 24.
`
`Also, the stoichiometric feedback combustion operating
`mode is made on the basis of the output of the O2 sensor so
`that sufficient engine output is efficiently obtained, while the
`air-fuel ratio is being maintained in a stoichiometric state. In
`this mode the premixed combustion based on the fuel
`injection on the intake stroke is performed.
`In addition, in the open-loop