United States Patent [191 Matsuoka

5,074,113 Dec. 24, 1991

[11] Patent Number:

[45] Date of Patent:

[54] AIR-FUEL RATIO CONTROL DEVICE OF AN INTERNAL COMBUSTION ENGINE

[75] Inventor:

[73] Assignee: I-Iiroki Matsueka, Susono, Japan

Toyota Jidosha Kabushiki Kaisha, Japan

[21] Appl. No.: 541,830

[22] Filed: Jun. 21, 1990

[30] Foreign Application Priority Data 11111.23, 1989 [JP] Japan ................................ .. 1-161592

[51] 111:. c1; .............................................. .. FOlN 3/22

[52] US. Cl. . . . . . . . . . . . . . . . . . . . . . .. 60/276; 60/285

[58] Field of Search ........................ .. 60/276, 274, 285

[56] References Cited U.S. PATENT DOCUMENTS

4,263,782 4/1981 Matsumoto ......................... .. 60/276

4,383,515 5/1983 Higashiyama ...................... .. 60/276

4,522,180 6/1985 Matsuoka et al.. 4,696,274 9/1987 Sato.

FOREIGN PATENT DOCUMENTS

59-87241 5/1984 Japan . 59-87242 5/1984 Japan . 63-79448 5/1988 Japan . 63-79449 5/1988 Japan .

63-118354 7/1988 Japan . 63-119844 8/1988 Japan .

l-8332 l/1989 Japan .

Primary Examiner-Douglas Hart

Attorney, Agent, or Firm-—Oliff & Berridge

[57] ABSTRACT An air-fuel ratio control device comprising two main air-fuel ratio detecting sensors arranged in ?rst and second exhaust passages upstream of three-way cata lysts respectively for detecting an air-fuel ratio in the ?rst and second exhaust passages, an auxiliary air-fuel ratio detecting sensor for detecting an air-fuel ratio in at least a ?rst exhaust passage of the ?rst and second ex haust passages downstream of the three-way catalysts, a deviation detecting unit for detecting a mutual devia tion between the air-fuel ratios in the ?rst and second exhaust passages, a ?rst control value controlling unit for controlling a control value in at least the ?rst cylin der bank to which the ?rst exhaust passage is con nected, on the basis of the value detected by the auxil- _ iary air-fuel ratio detecting sensor, a second control value controlling unit for controlling a control value in at least the second cylinder bank on the basis of the deviation detected by the deviation detecting unit to cancel the deviation, a feedback correction coef?cient controlling unit for controlling the feedback correction coef?cients in the cylinder banks on the basis of the values detected by the corresponding main air-fuel ratio detecting sensors and the control values, and an air-fuel ratio control unit for controlling the air-fuel ratio in the ?rst and second exhaust passages by the corresponding feedback correction coef?cients to obtain a predeter mined air-fuel ratio.

25 Claims, 22 Drawing Sheets

5,074,113 Sheet 1 of 22

mv

Dec. 24, 1991 US. Patent

US. Patent Dec. 24, 1991 Sheet 3 of 22 5,074,113

CALCULATION OF ' LFAF AND RFAF Fig 2

[READING OF DATA M02 F|g_2A FIQZB

304 cowmoNs FOR F'Q'ZC

EXECUTIONOFFEE FIQ'ZD

LEFT CYLINDER BANK MAIN AIR-FUEL RATIO DETECTING I

ESNSOR DETECTION SIGNAL -

310 Lv I § LVR' NOIRICH)

' YES(LEAN) 324

LC DI5Y>O LCDL)Y<O

LCDLY-O LCDLY-4)

3I6 328 LCDLY--LCDLY-l /~/ LCDLY-LCDLY+I /~/

LCDLY- LTDL ‘ LCDLY ~—LTDR

I 2/322 ' J J34 LFI—-O LFI~—I

Q5 .

US. Patent Dec. 24, 1991 Sheet 4 of 22 5,074,113

@ won 855 “an:

911$: \ 8165..

“ mom ~ _ .

JQJQEIT EEJZE: .HmmJuEHwT mw5i<5l “in: “3h: “35 “35

US. Patent Dec. 24, 1991 ' Sheet 5 of 22 5,074,113

CONDITIONS FOR EXECUTION OF FEED

CONTROL STAN)

AIR-FUEL RATIO DETECTING SENSOR DETECTION SIGNAL

RIGHT CYLINDER BANK MAIN / RVI

426 1

RCDLY-O f’ RCDLY-O "/

416 428 RCDLY~RCDLY~I ,4 RCDLY<~RCDLY+I /~/

YES / 432 RC DLY -—RTDL RCD LY-RTDR "/

1 422 ' I 4254

RF 1 -o ’/ R F 1 -1 ”/

G5

US. Patent Dec. 24, 1991 Sheet 6 of?22 5,074,113

%

wOve

‘VQ‘IN Qwmgm “Emmy

Nmm

ATOEVOZ

US. Patent Dec. 24, 1991 Sheet 10 of 22 5,074,113

A zmprwm V OJSUE \ _ 9R 0 XRE \ \ _

QR

oowtm \ _ 0? 01x85 \ _

0Q

0383 m§\ _ oamhrj

o;

US. Patent Dec. 24, 1991 ' Sheet 11 of 22 5,074,113

Fig.5

RICH I

“2111511116 1 Y I ‘ F R”? RFICLJ 1 1 1 PL LEAN

5 4

3 LCOX —

(B)CYCLE COUNTER

RCOX

LFFI (L l (C)COUNT FLAG I

FFFI ' |

(mFREoLENcY LFFZ ' L

5381mm ' I

E’?C‘GJT'ON RF” 0 1 (CL)———- ____________ __

LTCOX -/

(CR) _ """l n ” * _ _ _ _ - ->-7

RTCOX

US. Patent Dec. 24, 1991 Sheet 12 of 22

F/g6A

CALCULKTION OF CONSTANT INTEGRATION)

930

Fig.6 Fig.6A Fig.6B

RKIR LKIR -LKIR-/3*COR

5,074,113

LKlR --LKIR- #9 * COR LKIL-2A~LKIR

( RETURN )

US. Patent Dec. 24, 1991 Sheet 13 of 22 5,074,113

[/1070 RKIR LKIR Y

-LKIR+/3/COR I080

NO

YES r/logo RKIR—-C LKIR-A H00

1 2/150 1 / LRF-l LLF--O

H1O LKIL-— ZA-LKIR k

LKIR —-LKIR + fl/COR LKIL--2A-LKIR

I

US. Patent Dec. 24, 1991 Sheet 16 of 22 5,074,113

n ZmDPwm

.

U

zgjm‘qmmm . o EEIEVJmEK OM11

US. Patent Dec. 24, 1991

IL

Sheet 17 of 22 5,074,113

(FUEL INJECTION ) CONTROL I

A DATA READ IN A/ 1610 I

TAUO-KO£ xQ/Ne 1620

l

INCREASE COEFFICIENT I

CALCULATIGN OF ENGINE WARMUP [/1630

LTAU-TAUOV- LFAF IFWL+KB +1 I + Y

V1640 I

RTAU-TAUO - R FAF N I650 IFWL+KB+H +T

/ SET LTAU jlv I660

SET RTAU / 1

CONTROL SIGNAL / OUTPUT fv ‘680 RETURN C 3

US. Patent Dec. 24, 1991 Sheet 18 01122 5,074,1'13

Fig.9

-2'o -4o

0.

COOLING WATER TEMPERATURE THW (°C)

US. Patent Dec. 24, 1991 Sheet 19 of 22 5,074,113

CALCULATION OF SKIP VALUE

F /' g/OA Fig.IO

1700 Fig.IOA Fig.lOB ‘NO

[ A/D CONVERT / AND READ v2 ‘720

YES(LEFT BANK LEAN [IVIATICN ALR$-ALRS- 1*COR ALRS-ALRS+UCOR

ARRS~¢ARRS+ r*<:oR ARRS-A RRS-T/COR A, 1760 I

RRSR"'RRSR+ A FRS I

GUARD PROCESSING OF 1780 LRSR AND RRSR W

l

RRSL-RRSL— A RRS "’ T

GUARD PROCESSING OF ,800 LRSL AND RRSL -"

( RETURN )