United States Patent [19]
`Tabata et al.
`
`[54] ELECTRIC MOTOR VEHICLE HAVING
`MEANS FOR FULLY DISCHARGING PART
`OF ENERGY STORAGE DEVICE WHEN
`ENERGY AMOUNT IN THE OTHER PART IS
`LARGER THAN A THRESHOLD
`
`[75] Inventors: Atsushi Tabata, Okazaki; Yutaka
`Taga, Aichi-ken; Ryuji Ibaraki;
`Tsuyoshi Mikami, both of Toyota, all
`of Japan
`
`[73] Assignee: Toyota Jidosha Kabushiki Kaisha,
`Toyota, Japan
`
`[21] Appl. No.: 09/013,098
`[22]
`Filed:
`Jan. 26, 1998
`[30]
`Foreign Application Priority Data
`
`Feb. 14, 1997
`Aug. 5, 1997
`
`[JP]
`[JP]
`
`Japan .................................. .. 9-030650
`Japan .................................. .. 9-210977
`
`[51] Int. Cl.7 ..................................................... .. B60K 6/00
`[52] US. Cl. ............................................................ .. 180/165
`[58] Field of Search .................................. .. 180/653, 165,
`180/654, 65.5, 65.6, 306, 65.2, 65.8; 701/22;
`320/166
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`US006158541A
`[11] Patent Number:
`[45] Date of Patent:
`
`6,158,541
`Dec. 12, 2000
`
`5,184,058
`
`2/1993 Hesse et al. .............................. .. 320/4
`
`5,680,908 10/1997 Reed ......... ..
`. 180/653
`5,769,177
`6/1998 Wickman ............................. .. 180/653
`5,905,371
`5/1999 Limpaecher .......................... .. 323/288
`
`FOREIGN PATENT DOCUMENTS
`
`6/1993 Japan.
`5-137269
`5-328526 12/1993 Japan.
`
`Primary Examiner—Kevin Hurley
`Assistant Examiner—Kevin McKinley
`Attorney, Agent, or Firm—Oliff & Berridge, PLC
`
`[57]
`
`ABSTRACT
`
`An electrically driven automotive vehicle including an elec
`tric motor for driving the vehicle, an electric energy storage
`device for storing an electric energy for operating the
`electric motor, the storage device having a plurality of
`storage portions Which can be charged and discharged
`independently of each other, and a fully discharging device
`for fully discharging at least one of the storage portions,
`When an amount of electric energy stored in at least one of
`the other of the storage portions is larger than a predeter
`mined threshold.
`
`5,121,044
`
`6/1992 Goldman ................................... .. 320/2
`
`26 Claims, 28 Drawing Sheets
`
`[50
`
`I
`
`MOTOR/GENERATOR
`
`GENERATOR
`CONTROLLER
`
`FIRST CLUTCH
`
`CHARGING/
`DISCHARGING
`CONTROL
`PORTION
`
`
`
`
`
`HYBRID DRIVE CONTROLLER
`
`SECOND CLUTCH
`
`68
`
`INDICATOR
`
`
`
`ELECTRIC ENERGY STORAGE DEVICE
`
`
`
`
`
`
`
`
`
`FIRST STORAGE PORTION
`
`
`
`
`
`SECOND STORAGE PORTION
`
`Page 1 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12,2000
`
`Sheet 1 0f28
`
`6,158,541
`
`Page 2 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12,2000
`
`Sheet 2 0f28
`
`6,158,541
`
`a 24 /
`
`10
`
`f
`I
`
`18
`
`M
`
`FUEL INJECTION AMOUNT
`L__
`IGNITION TIMING
`
`1
`
`12]
`
`/’
`
`4Q SL1|STLi|SvL3lSL4|SLU SLTISLN
`
`42~~
`sTART SWITCH
`50
`43~— ACCELERATOR SENSOR mu ,/
`44~OR|vER/PAssENCER sENsOR
`45'» MOTOR SPEED sENsOR
`
`NM
`
`47~ ENGINESPEEDSENSOR
`
`NE
`
`6
`T“
`48~~ THROTTLE sENsOR
`49~~ VEHICLE SPEED SENSOR We)
`
`E
`Q
`E
`8
`§
`l5
`Q
`5
`
`<-0
`
`I
`
`52
`T
`J
`_>
`O€$—
`5&1‘ —O
`D<O <50
`
`FIG. 2
`
`Page 3 of 56
`
`FORD 1205
`
`

`

`S”U
`
`e
`
`m
`
`145,851
`
`
`
`
`
`6,Ell-IIE-Eflfll
`
`
`
`mmGE
`
`
`
`
`m2520mmémm$1230
`
`
`mIIHIIHIEHIHmn.n—mmmm0O0fig“$183029$:szfifim
`n,III-Illll-Iflléaz
`
`
`El-E-IE-IEEE
`
`mfil-Efi-Il-EIEHmmmm>mm
`
`Hfl-ED-II-Iflfll
`
`al-E-E-Il-fifll
`
`
`
`%Elna-IED-Iflflmag
`
`Page 4 of 56
`
`FORD 1205
`
`Page 4 of 56
`
`FORD 1205
`
`
`
`

`

`U.S. Patent
`
`Dec. 12, 2000
`
`Sheet 4 0f28
`
`6,158,541
`
`Page 5 of 56
`
`FORD 1205
`
`

`

`US. Patent
`
`Dec. 12,2000
`
`Sheet 5 0f 28
`
`6,158,541
`
`50
`
`GENERATOR
`
`
` MOTOR/GENERATOR
`CONTROLLER
` MOTOR/
`
`
`
`
`FIRST CLUTCH
`
`
`
`
`
`CHARGING/
`DISCHARGING
`CONTROL
`PORTION
`
`
`
`
`HYBRIDDRIVECONTROLLER
`
`
`
`
`ELECTRICENERGYSTORAGEDEVICE
`
`
`SECONDSTORAGEPORTION
`
`
`
`FIRSTSTORAGEPORTION
`
`
`
`INDICATOR
`
`SECOND CLUTCH
`
`
`
`
`
`
`46
`
`FIG. 5
`
`Page 6 of 56
`
`FORD 1205
`
`Page 6 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12,2000
`
`Sheet 6 0f28
`
`6,158,541
`
`(OPERATION MODE DETERMINING SUB-ROUTINE)
`
`S1
`
`ENGINE
`STARTIN<§YES
`REQUIRED?
`
`NO
`S7 vEIIICLE START YES
`<BY ENGINE
`REQUIRED?
`N0
`
`l
`S2 SELECTING
`NO
`MODE9
`‘—
`
`SELECTING S6
`MODE6
`
`84
`
`SOCZB?
`
`YES
`55 SELECTING
`MODE8
`
`88
`ACCELERATOR N0
`‘\DEPRESSED ?>——I
`51° SELECTING
`MODE 7
`
`YES
`
`S1
`
`S1
`
`S9 SELECTING
`MODE 5
`I
`
`NO
`
`518
`socgA? NO
`
`SOCZA?
`
`NO
`
`YES
`
`S13
`SELECTING
`MODE 1
`
`817
`SELECTING
`MODE2
`
`< ”‘
`
`$14
`
`A
`
`SELECTING
`MODE3
`
`SELECTING S19
`MODE4
`
`END
`
`Page 7 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12, 2000
`
`Sheet 7 0f28
`
`6,158,541
`
`Page 8 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12, 2000
`
`Sheet 8 0f 28
`
`6,158,541
`
`SOCA
`
`8008
`
`SOC
`
`FIG. 8
`
`Page 9 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12, 2000
`
`Sheet 9 0f 28
`
`6,158,541
`
`FIG. 9
`
`SA1
`ELECTRIC
`ENERGY STORAGE DEVICE
`NORMAL ?
`
`NO SA2
`
`YES
`
`FUEL AMOUNT ; a?
`
`3
`SA
`
`YES
`
`NO
`
`ES
`8A4
`Y
`800 ; IIIAI ?
`
`NO
`
`A5
`S
`
`YES
`
`T
`
`A6
`8
`
`YES
`
`SOCB ; MA2 ?
`
`SAT 1
`SOCA ; MA3 ?
`
`YES xm
`
`NO
`
`SA?
`DISCHARGING
`sTORAGE
`PORTION 64
`AND GI-IARGING
`STORAGE
`PORTION 66
`
`SA12
`ORARGING
`sTORAGE
`PORTION 64,
`AND OIsOIIARGING
`STORAGE
`PORTION 66
`
`SA13
`< SOCB = o '2
`
`NO
`
`SA14
`
`YES
`
`F1 = I
`I
`
`8A9
`
`SAT 0
`
`F1 = 0
`
`TBT = 0
`
`(
`
`RETURN
`
`)
`
`Page 10 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12, 2000
`
`Sheet 10 0f 28
`
`6,158,541
`
`FIG. 10
`
`ELECTRIC
`ENERGY STORAGE DEVICE
`NORMAL 7
`
`S87
`CHARGING
`STORAGE
`PORTION 64
`AND DISCHAFIGING
`STORAGE
`POFITION 66
`
`YES ‘
`S812
`DISCHAFIGING
`STORAGE
`PORTION 64
`AND CHARGING
`STORAGE
`PORTION 66
`
`S810
`
`(
`
`RETURN
`
`)
`
`Page 11 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12,2000
`
`Sheet 11 0f28
`
`6,158,541
`
`S01
`SOCAéMCI?
`
`NO
`
`FIG. 11
`
`A
`
`$02
`SOCB ; M02 ?
`
`SC3
`SELECTING
`CHARGING MODE,
`AND CHARGING
`STORAGE
`PORTION 66
`
`EV
`
`SDI
`SOCB é MDI ?
`
`FIG. 12
`
`NO
`
`A
`
`$02
`SOCA ; MD2?
`
`SD3
`
`SELECTING
`CHARGING MODE,
`AND CHARGING
`STORAGE
`PORTION 64
`
`A“
`
`Page 12 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12,2000
`
`Sheet 12 0f28
`
`6,158,541
`
`FIG. ‘I3
`
`SE1
`
`ELECTRIC
`ENERGY STORAGE DEVICE >
`NORMAL ?
`
`STORAGE
`DEVICE TEMP. ; T1 ?
`
`NO
`
`FULL
`DISCHARGING REQUIRED ?
`
`SE4
`
`SOC Z 35% ?
`
`NO
`
`YES
`
`SE5
`CHARGING
`POSSIBLE ?
`
`SE6
`CHARGING ONE OF STORAGE
`PORTIONS 64, 66 TO 35%
`OF FULL CAPACITY
`I___________
`
`SE7
`FULLY DISCHARGING THE OTHER
`STORAGE PORTION 64,66
`
`( RETURN )
`
`Page 13 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12,2000
`
`Sheet 13 0f28
`
`6,158,541
`
`FIG. 14
`
`ELECTRIC
`ENERGY STORAGE DEVICE
`NORMAL?
`
`STORAGE
`DEVTCE TEMP. _>-= T1 ?
`
`FULL
`DISCHARGING REQUIRED?
`
`SOC Z 40% ?
`
`NO
`
`SP5
`CHARGING
`POSSIBLE ?
`
`YES
`
`CHANGING LOWER LIMIT A
`OF SOC TO 40% AND
`CHARGING ONE OF STORAGE
`PORTIONS 64, 66 TO 40%
`OF FULL CAPACITY
`L—i
`
`SF7
`FULLY DISCHARGING THE OTHER
`STORAGE PORTION 64, 66
`
`( RETURN )
`
`Page 14 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12,2000
`
`Sheet 14 0f28
`
`6,158,541
`
`FIG. 15
`
`861
`
`ELECTRIC
`ENERGY STORAGE DEVICE
`NORMAL ?
`
`STORAGE
`DEVICE TEMP. 2 T1 ?
`
`COMPLETE
`DISCHARGING REQUIRED?
`
`CONTROLLING ENERGY
`AMOUNT SOC2 STORED
`IN ONE OF STORAGE
`PORTIONS 64, 66
`I—__
`
`866
`FULLY DISCHARGING THE OTHER
`STORAGE PORTION 64, 66
`
`I RETURN )
`
`Page 15 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12,2000
`
`Sheet 15 0f28
`
`6,158,541
`
`mi. FIG. 16
`
`NO
`
`NO
`
`SHI
`
`ELECTRIC
`ENERGY STORAGE DEVICE >
`NORMAL ?
`
`8H2
`
`YES
`
`STORAGE
`DEVICE TEMP. ; TI ? >
`
`SH3
`
`YES
`
`N0
`FULL
`DISCHARGING REQUIRED? >-————-——
`
`YES
`
`8H4
`30% .3.
`
`g 40%
`
`N0
`__‘"
`
`YES
`
`SH5
`CHANGING UPPER LIMIT
`B OF SOC AND CONTROLLING
`CHARGING AND DISCHARGING
`OF STORAGE DEVICE 58
`
`SH6
`FULLY DISCHARGING ONE OF
`STORAGE PORTIONS 64, 66
`
`I RETURN I
`
`Page 16 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12,2000
`
`Sheet 16 0f28
`
`6,158,541
`
`S|1
`
`ELECTRIC
`ENERGY STORAGE DEVICE
`NORMAL?
`
`NO
`
`STORAGE
`DEVICE TEMP. ; T1 ?
`
`S|3
`
`FULL
`DISCHARGING REQUIRED?
`
`Sl4
`
`YES
`
`SOG ; 40%?
`
`YES
`
`8'8
`
`8'9
`
`FULLY DISCHARGING ONE OF
`STORAGE PORT|ONS e4, 66
`i
`RESTORING UPPER LIMIT B
`TO ORIGINAL VALUE
`
`( RETURN )
`
`PPRRLTPB
`
`U OF SOC
`I
`
`DEFFEUTE'NG
`DISCHARGING
`l
`NORMAL
`CONTROL
`OF STORAGE
`DEVICE
`
`Sl6
`
`5”
`
`Page 17 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12,2000
`
`Sheet 17 0f28
`
`6,158,541
`
`FIG. 18
`
`SJI
`
`ELECTRIC
`ENERGY STORAGE DEVICE
`NORMAL?
`
`STORAGE
`DEVICE TEMP. 2 T1 ?
`
`8J3
`
`CHARGING
`‘ ND DISCHARGING EFFICIENCY
`é S2 ?
`
`NO
`
`FULL
`DISCHARGING REQUIRED?
`
`8J7
`IMPLEMENTING FULL DISCHARGING
`
`FULLY DISCHAFIGING
`THE sesftogg??gggnw
`
`SJ4
`
`ACCORE'SIIiBTSSZREEJSENT Y
`DISCHAFIGING SEQUENCE
`
`BEEN LOWEFIED TO 82
`
`8J5
`
`CHANGING DISCHARGING
`SEQUENCE OF STORAGE
`PORTIONS 64, as
`
`I RETURN I
`
`Page 18 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12,2000
`
`Sheet 18 0f28
`
`6,158,541
`
`ONE OF THE
`TwO STORAGE PORTIONS A, B
`DEFECTIVE '2
`
`5K5
`STORAGE
`PROCESS OF BEING?FMLLY
`
`DISCHARGED .
`
`FIG. 19
`
`YES
`
`8K2
`
`|
`USING THE OTHER
`STORAGE PORTION
`|
`8K3 CHANGING LOWER
`LPMIBTQEEQECDTQN
`SOCA , 5008
`l
`INDICATING
`DEFECTIvE STORAGE
`PORTION e4, 66
`
`8K4
`
`8K6
`
`USING STORAGE
`PORTION6466
`NOT IN THE PROCESS
`OF BEING FULLY
`DISCHARGED
`l
`8K7 CHANGING LOWER
`AND UPPER LIMITS
`A, B OF SOC TO
`LIMITS BASED ON
`SOCA , SOCB
`
`8K8
`
`MAINTAINING ORIGINAL
`LIMITS A, B OF SOC
`
`( RETURN )
`
`Page 19 of 56
`
`FORD 1205
`
`

`

`U.S. Patent
`
`Dec. 12,2000
`
`Sheet 19 0f28
`
`6,158,541
`
`FIG. 20
`
`SL1
`
`STORAGE
`PORTION 64 66 IN TH
`E
`PROCESS OF BEING FU
`LLY
`DISCHARGED ?
`
`SL2 CALCULATING TOTAL
`ENERGY AMOUNT $00
`I
`SL3 ExECLITING SUB-ROUTINE OF FIG. 6
`BASED ON THE CALCULATED
`ToTAL ENERGY AMOUNT
`I
`CoNTRoLLING CHARGING/
`D'%%HI=’I>R§E%I%XBQN%OENPR%TION
`AMOUNTS SOCA AND 8008
`
`SL4
`
`SL5
`
`SL6
`
`,(NNSNJGPIPNEGRLSIWIEI'Q
`A, B OF SOC TO
`LIMITS BASED ON
`800"’ 80GB
`l
`FLGLNLEKGJIIPSSCT'NQIGGQG
`PCRTIoNS e4, 66
`I
`SL7 ExECuTING SUB-ROUTINE OF FIG. 6
`BASED ON CHANGED LCwER
`AND uPPER LIMITS A, B
`
`SL8
`
`USING THE OTHER
`STCRAGE PoRTICN 64, as
`
`( RETURN )
`
`Page 20 of 56
`
`FORD 1205
`
`

`

`US. Patent
`
`Dec. 12,2000
`
`Sheet 20 0f 28
`
`6,158,541
`
`ELECTRIC
`ENERGY STORAGE DEVICE
`
`FIG. 21
` 8M1
`NORMAL ?
`
`
` STORAGE
`DEVICE TEMP. ; TI ?
`
`
`8M4
`
`YES
`
`RUNNING DISTANCE ; Y‘I ?
`
`SM5
`
`OPERATING TIME 2 Y3?
`
`M78
`
`
`
`_—<_ Y4 ?
`
`
`
`
`
`
`
`
` DISCHARGING EFFICIENCY
`
`
`
`FULLY DISCHARGING ONE OF
`STORAGE PORTIONS 64, 66
`
`
`
`Page 21 of 56
`
`FORD 1205
`
`Page 21 of 56
`
`FORD 1205
`
`

`

`US. Patent
`
`Dec. 12,2000
`
`Sheet 21 0f 28
`
`6,158,541
`
`FIG. 22
`
`SN1
`
` NO
`ELECTRIC
`ENERGY STORAGE DEVICE
`
`
`NORMAL ?
`
`NO
`
`YES
`
`8N2
`
`
`FULL
`
`
`DISCHARGING REQUIRED?
`
`
`
`
`
` STORAGE
`
`DEVICE TEMP. ; T1 ?
`
`
`
`
`NO
`
`FULL
`DISCHARGING POSSIBLE ?
`
`8N3
`
`
`
`
`
`
`
`TEMPERATURE
`
`RISE POSSIBLE?
`
`
`3N5
`
`STORAGE DEVICE
`TEMP. RAISED
`
`8N7
`
`FULLY DISCHARGING ONE OF
`STORAGE PORTIONS 64, 66
`e———————
`
`Page 22 of 56
`
`FORD 1205
`
`Page 22 of 56
`
`FORD 1205
`
`

`

`US. Patent
`
`Dec. 12,2000
`
`Sheet 22 0f 28
`
`6,158,541
`
`FIG. 23
`
`801
`
`NO
`
`STORAGE
`DEVICE TEMP. ; T1 ?
`
`802
`
`YES
`
`STORAGE
`PORTION 64,66 FULLY >
`
`YES
`
`CALCULATING AMOUNT OF CHANGE H
`OF CHARGING AND DISCHARGING
`EFFICIENCY BEFORE AND AFTER
`FULL DISCHARGING
`
`DISCHARGING ?
`
`
`
`
`
`CALCULATING PERCENT VALUE K1
`OF RECOVERY OF CHARGING
`AND DISCHARGING EFFICIENCY
`BY FULL DISCHARGING
`
`
`CHECKING SERVICE LIFE
`
`OF STORAGE PORTION 64, 66
`
`
`
`
`NOMINAL
`SERVICE LIFE REACHED? >
`
`
`YES
`
`INDICATING THAT NOMINAL SERVICE
`LIFE HAS BEEN REACHED
`
`
`
`NO
`
`809
`
`USING ONLY THE NORMAL
`
`
`
`
`STORAGE PORTION 64, 66
`
`Page 23 of 56
`
`FORD 1205
`
`Page 23 of 56
`
`FORD 1205
`
`

`

`US. Patent
`
`Dec. 12,2000
`
`Sheet 23 0f 28
`
`6,158,541
`
`FIG. 24
`
`SP1
`
`
`
`
`
`
`
`STORAGE
`DEVICE TEMP. ; T1 ?
`
`
`
`START SWITCH 42 OFF ?
`
`
`
`
`
`DRIVER/PASSENGER 44
`DETECTED ?
`
`NO
`
`FULLY DISCHARGING ONE OF
`STORAGE PORTIONS 64, 66
`
`INDICATING FULL DISCHARGING
`OF STORAGE PORTIONS 64,66
`
`
`
`
`
`
`
`
`
`Page 24 of 56
`
`FORD 1205
`
`Page 24 of 56
`
`FORD 1205
`
`

`

`US. Patent
`
`Dec. 12,2000
`
`Sheet 24 0f 28
`
`6,158,541
`
`130
`
`Page 25 of 56
`
`FORD 1205
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`US. Patent
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`Dec. 12,2000
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`Sheet 25 0f 28
`
`6,158,541
`
`172
`
`132
`
`ENGINE
`
`174
`
`FIRST
`MOTOR/
`GENERATOR
`
`138
`
`178
`
`134
`
`ELECTRIC
`ENERGY
`STORAGE
`DEVICE
`
`
`
`FIRST
`MOTOR/
`
`
`GENERATOR
`CONTROLLER
`
`5
`:1
`o
`g
`
`OO
`
`
`
`SECOND
`MOTOR/
`GENERATOR
`CONTROLLER
`
`
`
`
`
`
`1 76
`
`BATTERY
`
`
`
`SERIgDR
`
`SECOND
`MOTOR/
`
`GENERATOR
`
`FIG. 26
`
`180
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`US. Patent
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`Dec. 12,2000
`
`Sheet 26 0f 28
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`6,158,541
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`FIG. 27
`
`NO
`
`ELECTRIC
`ENERGY STORAGE DEVICE >
`
`NORMAL ?
`
`YES
`
`STORAGE
`DEVICE TEMP. ; T1 ?
`
`FULL
`DISCHARGING REQUIRED ? >
`
`YES
`
`YES
`
`FULLY DISCHARGING
`STORAGE DEVICE 178
`
`MOTOR/GENERATOR 138
`OPERATED AS ELECTRIC
`MOTOR ?
`
`NO
`
`
`
`
`
`
`
`
`NORMAL CONTROL OF HYBRID
`DRIVE SYSTEM 130
`
`
`
`SECOND MOTOR/GENERATOR 134
`OPERATED AS ELECTRIC GENERATOR
`
`807
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`US. Patent
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`Dec. 12,2000
`
`Sheet 27 0f 28
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`6,158,541
`
`190
`
`00
`N
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`US. Patent
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`Dec. 12, 2000
`
`Sheet 28 0f 28
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`6,158,541
`
`mm.GE
`
`Inna-Ila-I
`
`QmmmmZO_mm_s_w2<m._.
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`Nl_.H—vmmmNmPmNO_.0CEIII-I...a;
`%%%E:5
`
`
`
`III-l-I-II$502
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`6,158,541
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`1
`ELECTRIC MOTOR VEHICLE HAVING
`MEANS FOR FULLY DISCHARGING PART
`OF ENERGY STORAGE DEVICE WHEN
`ENERGY AMOUNT IN THE OTHER PART IS
`LARGER THAN A THRESHOLD
`
`This application is based on Japanese Patent Application
`No. 9-210977 filed Aug. 5, 1997 and claiming the priority of
`Japanese Patent Application No. 9-30650 filed Feb. 14,
`1997, the contents of these two applications being incorpo-
`rated hereinto by reference.
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`
`Not applicable
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`
`The present invention relates in general to an electrically
`driven automotive vehicle, and more particularly to tech-
`niques for prolonging service life of an electrical energy
`storage device used on the vehicle.
`2. Discussion of the Related Art
`
`There is known an electrically driven or powered auto-
`motive vehicle of hybrid type including an internal com-
`bustion engine, an electric generator driven by the internal
`combustion engine to generate an electric energy, an electric
`energy storage device for storing the electric energy gener-
`ated by the electric generator, and an electric motor operated
`by the electric energy supplied from the electric energy
`storage device. An example of the hybrid type electric
`vehicle is disclosed in JP-A-5-328526. In this hybrid type
`electric vehicle, the internal combustion engine is operated
`as needed, to drive the electric generator for generating an
`electric energy, so that a continuously running distance of
`the electric motor vehicle can be made sufficiently large,
`without having to use the electric energy storage device
`having a considerably large storage capacity. Further, the
`amount of fuel consumption by the engine and the amount
`of exhaust gas emissions from the engine during generation
`of the electric energy by the electric generator can be
`reduced by operating the engine at a speed at which the fuel
`economy is the highest, and by holding the engine off when
`the generation of the electric energy is not necessary. Owing
`to these practical advantages, the electric motor vehicle of
`the hybrid type has been drawing an attention of the indus-
`try.
`The electric generator is usually operated by the engine to
`charge the electric energy storage device,
`for avoiding
`insufficiency of the electric energy stored in the storage
`device during running of the vehicle. For instance,
`the
`electric energy stored in the storage device is maintained
`within a range of 30—80% of its full storage capacity
`(nominal storage capacity), so that a given amount of
`electric energy is always left in the storage device.
`However, some reports indicate that repeated charging of
`the electric energy storage device before it is fully dis-
`charged may cause a phenomenon of a gradual decrease in
`the storage capacity (maximum energy amount that can be
`stored in the storage device) before expiration of the
`expected service life of the storage device. To prevent this
`problem, it is known to completely or fully discharge the
`storage device before each charging of the storage device.
`SUMMARY OF THE INVENTION
`
`It is therefore an object of the present invention to provide
`an electrically driven automotive vehicle having an electric
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`motor operated by an electric energy supplied from an
`electric energy storage device, wherein the storage device is
`free from the conventionally experienced phenomenon of
`gradual decrease in the storage capacity due to repeated
`charging thereof.
`The above object may be achieved according to a first
`aspect of this invention, which provides an electrically
`driven automotive vehicle comprising: an electric energy
`storage device for storing an electric energy, the electric
`energy storage device including a plurality of storage por-
`tions which can be charged and discharged independently of
`each other; an electric motor operated by the electric energy
`supplied from the electric energy storage device, for running
`the vehicle; and fully discharging means for fully discharg-
`ing a first part of the electric energy storage device which
`consists of at least one of the plurality of storage portions,
`when an amount of electric energy stored in a second part of
`the electric energy storage device which consists of at least
`one of the other of the plurality of storage portions is larger
`than a predetermined threshold.
`In the electrically driven automotive vehicle constructed
`according to the first aspect of this invention, the first part of
`the electric energy storage device is fully discharged when
`the amount of electric energy stored in the second part of the
`storage device is larger than a predetermined threshold. This
`arrangement prevents a decrease in the storage capacity of
`the electric energy storage device due to repeated charging,
`while avoiding insufficiency of the electric energy amount
`for running the vehicle.
`The first part of the storage device consists of at least one
`of the plurality of storage portions, while the second part
`consists of at least one of the other of the plurality of storage
`portions. Therefore, the plurality of storage portions of the
`storage device may include at least one storage portion
`which does not belong to the first and second parts and
`which is not at all discharged or is partially discharged to a
`predetermined extent.
`The above-indicated object may also be achieved accord-
`ing to a second aspect of this invention, which provides an
`electrically driven automotive vehicle comprising: electric-
`ity generating means for generating an electric energy; an
`electric energy storage device for storing the electric energy
`generated by the electricity generating means, the electric
`energy storage device including a plurality of storage por-
`tions which can be charged and discharged independently of
`each other; an electric motor operated by the electric energy
`supplied from the electric energy storage device, for running
`the vehicle; and fully discharging means for fully discharg-
`ing a first part of the electric energy storage device which
`consists of at least one of the plurality of storage portions,
`when an amount of electric energy stored in a second part of
`the electric energy storage device which consists of at least
`one of the other of the plurality of storage portions is larger
`than a predetermined threshold.
`In the electrically driven automotive vehicle according to
`the second aspect of the invention, too, at least one of the
`storage portions as the first part of the storage device is fully
`discharged when the amount of electric energy stored in at
`least one of the other of the storage portions as the second
`part of the storage device is larger than a predetermined
`threshold. Accordingly, the second aspect of the invention
`provides the same advantages as the first aspect of the
`invention described above.
`
`The fully discharging means is preferably arranged to
`operate the electric motor for running the vehicle, with the
`electric energy stored in the first part of the electric energy
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`6,158,541
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`3
`storage device, so that the first part of the storage device is
`fully discharged. In this case, the electric energy generated
`by the electricity generating means is preferably stored in
`the second part of the storage device. However, the full
`discharging of the first part may be effected by connecting
`the first part of the storage device to suitable energy con-
`suming means such as an electric heater or resistor, so that
`the electric energy in the first part is consumed by the energy
`consuming means. In this case, the first part can be posi-
`tively fully discharged in a comparatively short time. Where
`an engine which cooperates with the electric motor to
`function as the drive power source of the vehicle is utilized
`as part of the electricity generating means, the full discharg-
`ing of the first part may be accomplished relatively rapidly,
`by restricting the use of the engine as the drive power source
`for running the vehicle and comparatively frequently using
`the electric motor as the drive power source, so that the
`electric energy in the first part of the storage device can be
`rapidly consumed by the electric motor.
`The vehicle according to the second aspect of the inven-
`tion may further comprise fully charging means for fully
`charging at least one of the plurality of storage portions of
`the electric energy storage device when the amount of
`electric energy stored in at least one of the other of the
`storage portions is smaller than a predetermined lower limit.
`Preferably, the fully charging means is adapted such that the
`electric energy generated by the electricity generating means
`is stored primarily in the above-indicated at least one of the
`plurality of storage portions of the storage device, while the
`electric motor is operated primarily by the electric energy
`stored in the above-indicated at least one of the other of the
`
`plurality of storage portions of the storage device. However,
`it is possible to operate the electricity generating means for
`the purpose of fully charging the above-indicated at least one
`of the storage portions, unless the operation of the electricity
`generating means for this purpose is not desirable for some
`other reason.
`
`The vehicle according to the second aspect of the inven-
`tion which comprises the fully discharging means and may
`optionally comprise the fully charging means may have
`various arrangements as described below.
`(a) The plurality of storage portions of the storage device
`are sequentially fully discharged in a predetermined order.
`Where the storage device consists of two storage portions,
`these two storage portions are alternately fully discharged,
`for instance, at a predetermined time interval. The storage
`portions may be sequentially fully charged in a predeter-
`mined order.
`
`(b) The plurality of storage portions of the storage device
`are sequentially fully discharged at a predetermined interval,
`depending upon the cumulative time of use of the storage
`device, or the cumulative running time or distance of the
`electric vehicle (hybrid vehicle). For instance, the storage
`portions are selectively fully discharged each time the cumu-
`lative running distance has reached a predetermined value.
`Similarly, the storage portions may be sequentially or selec-
`tively fully charged at a predetermined interval. The fully
`discharging interval may be determined by experiments so
`that the storage capacity of each storage portion of the
`storage device can be recovered by the full discharging,
`before the storage capacity is excessively reduced due to
`repeated charging of the storage device.
`(c) The electricity generating means is inhibited from
`operating to fully charge the storage portion or portions of
`the storage device, while the vehicle is at rest with the drive
`power source held in its idling state with the accelerator
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`pedal being placed at its non-operated position. The opera-
`tion of the electricity generating means such as an engine
`may cause vibrations and noises, which would give a
`discomfort to the passengers when the vehicle is at rest in the
`idling state.
`(d) The fully discharging means is inhibited from oper-
`ating when an amount of a fuel used for the electricity
`generating means is smaller than a predetermined lower
`limit. Where an engine is used as part of the electricity
`generating means, a gasoline is used as the fuel. Where a fuel
`cell is used as the electricity generating means, hydrogen or
`oxygen is used as the fuel.
`(e) The fully discharging means is operated only where all
`of the plurality of storage portions of the storage device are
`normally functioning. This condition also applies to the fully
`charging means if provided.
`(f) The fully discharging means is operated when the total
`electric energy amount of the storage device is larger than a
`predetermined lower limit (e.g., about 30% of the nominal
`or full storage capacity of the storage device).
`(g) The fully discharging means is operated when the total
`electric energy amount of the storage device is smaller than
`a predetermined upper limit (e.g., about 80% of the nominal
`or full storage capacity).
`The operation of the fully discharging means according to
`the first and second aspect of this invention is effective
`particularly when the electric energy storage device is
`adapted to be normally used within a predetermined range of
`its total electric energy amount (e.g., between 30% and 80%
`of the nominal storage capacity of the storage device), in
`which the charging and discharging efficiency is sufficiently
`high. The storage device may be selected from various
`secondary batteries or cells, such as nickel-cadmium cells
`and nickel-hydrogen cells.
`The fully discharging means need not be adapted to
`discharge the appropriate storage portion or portions of the
`storage device until the electric energy amount in the storage
`portion or portions is completely zeroed. Rather, the fully
`discharging means may be adapted to reduce the electric
`energy amount of each appropriate storage portion to a value
`below the lower limit above which the storage portion is
`normally used. Similarly, the fully charging means need not
`be adapted to charge each appropriate storage portion until
`the electric energy amount is increased to the full 100%
`value of the nominal storage capacity, but may be adapted to
`increase the electric energy amount to a value above the
`upper limit below which the storage portion is normally
`used.
`
`According to one preferred form of the second aspect of
`the invention,
`the electrically driven automotive vehicle
`further comprises charging control means for operating the
`electricity generating means to charge the second part of the
`electric energy storage device when the amount of electric
`energy stored in said first part of the storage device has been
`reduced to a predetermined threshold by the fully discharg-
`ing means.
`The above form of the invention is effective to prevent
`insufficiency of the total electric energy amount of the
`electric storage device due to the full charging of the
`selected storage portion or portions, and therefore permits
`running of the vehicle by the electric motor even when the
`fully charging means is operated.
`The charging control means need not be adapted to charge
`all of the storage portions of the second part of the storage
`device, but may be adapted to charge a selected one of the
`storage portions of the second part.
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`The charging control means may be adapted to interrupt
`the operation of the fully discharging means when the
`electric energy amount stored in the first part of the storage
`device has been reduced to the predetermined threshold by
`the fully discharging means, and charge the second part of
`the storage device until the electric energy amount stored in
`the second part is increased to a predetermined value.
`The object indicated above may also be achieved accord-
`ing to a third aspect of this invention, which provides an
`electrically driven automotive vehicle comprising: an elec-
`tric energy storage device for storing an electric energy, the
`electric energy storage device including a plurality of stor-
`age portions which can be charged and discharged indepen-
`dently of each other; an electric motor operated by the
`electric energy supplied from the electric energy storage
`device, for running the vehicle; and fully discharging means
`for transferring the electric energy from a first part of the
`electric energy storage device which consists of at least one
`of the plurality of storage portions, to a second part of the
`electric energy storage device which consists of at least one
`of the other of the plurality of storage portions, to thereby
`fully discharge the first part, when a total amount of electric
`energy stored in the electric energy storage device is larger
`than a predetermined threshold.
`In the electrically driven automotive vehicle constructed
`according to the third aspect of this invention, the first part
`of the electric energy storage device is fully discharged
`when the total electric energy amount of the storage device
`is smaller than a predetermined threshold. The first part is
`fully discharged such that the electric energy is transferred
`from the first part to the second part. This arrangement
`prevents a decrease in the storage capacity of the electric
`energy storage device due to repeated charging, while avoid-
`ing insufficiency of the electric energy amount for running
`the vehicle.
`
`The fully discharging means according to the third aspect
`of the invention is preferably adapted to be operated when
`at least one of various conditions other than the condition
`
`that the total electric energy amount of the storage device is
`larger than the predetermined threshold. Those other condi-
`tions include: a condition that the temperature of the storage
`device is higher than a predetermined lower limit; a condi-
`tion that the running time of the vehicle has exceeded a
`predetermined value; a condition that the running distance of
`the vehicle has exceeded a predetermined value; a condition
`that the charging and discharging efficiency of the storage
`device has been lowered below a predetermined value; and
`a condition that the cumulative time of use of the storage
`device has exceeded a predetermined value. The first and
`second parts of the storage device may be alternately fully
`discharged.
`According to a first preferred form of the third aspect of
`this invention,
`the electrically driven automotive vehicle
`further comprises: electricity generating means for generat-
`ing the electric energy; and charging control means for
`operating the electricity generating means to generate the
`electric energy for charging the electric energy storage
`device until the total amount of electric energy stored in the
`electric energy storage device is increased to the predeter-
`mined threshold, before the fully discharging means is
`operated to fully discharge the first part of the electric energy
`storage device.
`In the above preferred form of the invention, the electric
`energy storage device is charged until
`the total electric
`energy amount is increased to the predetermined threshold
`before the fully discharging means is operated to fully
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`discharge the first part of the storage device. This form of the
`invention permits full discharging of the first part of the
`storage device while avoiding insufficiency of the electric
`energy amount for running the vehicle.
`In one advantageous arrangement of this form of the third
`aspect of the invention invention,
`the charging control
`means is operated to charge the second part of the electric
`energy storage device. This arrangement assures a reduced
`amount of energy loss upon transfer of the electric energy
`from the first part to the second part. In this arrangement, the
`amount of the electric energy to which the second part is
`charged is preferably selected to be sufficient for operating
`the electric motor to run the vehicle, but to be smaller than
`an upper limit above which the second part is excessively
`charged when the electric energy is transferred from the first
`part to the second part by the fully discharging means.
`According to a second preferred form of the third aspect
`of the invention, the fully discharging means is adapted to
`transfer the electric energy from the first part of the electric
`energy storage device to the second part to fully discharge
`the first part, when the amount of electric energy stored in
`the second part of the electric energy storage device is held
`within a predetermined range