[19]
`United States Patent
`5,934,395
`[11] Patent Number:
`[45] Date of Patent: Aug. 10, 1999
`Koide et al.
`
`
`
`U8005934395A
`
`[54] HYBRID VEHICLE DRIVE SYSTEM HAVING
`TWO MOTOR/GENERATOR UNITS AND
`ENGINE STARTING MEANS
`
`[75]
`
`Inventors: Takeharu Koide, Toyota; Hideaki
`Matsui, Aichi-ken; Mitsuhiro Nada,
`Toyota, all of Japan
`
`[73] Assignee: Toyota Jidosha Kabushiki Kaisha,
`Toyota-shi, Japan
`
`[21] Appl. No.: 08/730,762
`
`[22]
`
`Filed:
`
`Oct. 15, 1996
`
`[30]
`
`Foreign Application Priority Data
`
`[JP]
`[JP]
`
`Oct. 18, 1995
`Sep. 5, 1996
`
`Japan .................................... 7—268922
`Japan
`.. 8—235063
`
`
`[51]
`Int. Cl.6 ........................
`B60K 6/04
`[52] U.S.Cl. .............................. ISO/65.2
`
`[58] Field of Search .................................. 180/652, 65.3,
`180/65.4, 65.6; 123/3
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`4,095,664
`6/1978 Bray ....................................... 180/65.4
`4,319,140
`3/1982 Paschke ............. 290/45
`
`4,335,429
`6/1982 Kawakatsu ...........
`180/652
`4,407,132 10/1983 Kawakatsu et al.
`.
`.. 180/654
`
`5,343,970
`9/1994 Severinsky ...........
`180/656
`....................... 180/652
`5,492,189
`2/1996 Kriegler et al.
`
`5,558,173
`5,558,175
`5,562,566
`5,713,425
`
`9/1996 Sherman ................................ 180/654
`9/1996 Sherman .
`180/65.2
`
`10/1996 Yang ..................
`180/65.2
`2/1998 Buschhaus et al.
`................... 180/65.2
`
`FOREIGN PATENT DOCUMENTS
`
`0—528—412—A1
`A—0—552—140
`31—40—492—A1
`A—50—30223
`A—3—273933
`A—5—319110
`A—7—172196
`
`.
`.
`
`2/1993 European Pat. Off.
`7/1993 European Pat. Off.
`6/1982 Germany .
`3/1975
`Japan .
`12/1991
`Japan .
`12/1993
`Japan .
`7/1995
`Japan .
`
`Primary Examiner—J. J. Swann
`Assistant Examiner—Frank Vanaman
`
`Attorney, Agent, or Firm—Cliff & Berridge, PLC
`
`[57]
`
`ABSTRACT
`
`A hybrid drive system for a motor vehicle, including an
`engine operated by combustion of a fuel, a first motor/
`generator, a distributing mechanism for mechanically dis-
`tributing an output of the engine to the first motor/generator
`and an output member, a second motor/generator whose
`rotary force is transferred to a power transmitting path
`between the output member and a drive wheel of the motor
`vehicle, and wherein an engine starting device is provided
`for operating the first motor/generator to crank the engine
`through the distributing mechanism, for thereby starting the
`engine.
`
`7 Claims, 16 Drawing Sheets
`
`
`
`CONTROL
`
`FIRST
`MOTOR/
`GENERATOR
`CONTROL
`UNIT
`
`SECOND
`MOTOR/
`GENERATOR
`
`ELECTRICAL
`ENERGY
`STORAGE
`DEVICE
`
`
`
`1of27
`
`FORD 1417
`
`1 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10, 1999
`
`Sheet 1 0f 16
`
`5,934,395
`
`NF
`
`
`
`
`4IIIIIIIIII~III _"'|‘_i'|_'!.“l
`
` Hll-.uMflhfl/flflnwiui\\il\/
`
`17”»VivV
`AfiikAKWWFCMFF.1!
`
`
`m:
`
`2mMIanfla‘11111131?Ifllrwm
`
`\\\\\..
`
`
`20f27
`
`FORD 1417
`
`2 of 27
`
`FORD 1417
`
`
`
`

`

`US. Patent
`
`Aug. 10,1999
`
`Sheet 2 0f 16
`
`5,934,395
`
`
`
`FIRST
`MOTOR/
`GENERATOR
`
`COLLFNIBTOL
`
`SECOND
`MOTOR/
`GENERATOR
`
`CONTROL
`
`ELECTRICAL
`ENERGY
`STORAGE
`
`DEVICE
`
`3of27
`
`FORD 1417
`
`3 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10,1999
`
`Sheet 3 0f 16
`
`5,934,395
`
`42
`
`CONTROLLER
`
`ENGINE
`
`FIRST MOTOR/
`GENERATOR
`CONTROL UNIT
`
`SECOND MOTOR/
`GENERATOR
`CONTROL UNIT
`
`12
`
`36
`
`38
`
`44
`
`54
`
`PARKING BRAKE E
`
`SWITCH
`
`"
`
`— MEMORY DEVICE
`
`46
`
`s2
`
`FIGB
`
`4 of 27
`
`FORD 1417
`
`4 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10,1999
`
`Sheet 4 0f 16
`
`5,934,395
`
`FIG.4
`
`V SI
`
`ENGINE START
`COMMAND?
`
`YES
`
`PROMPTING VEHICLE
`OPERATOR TO ACTUATE
`PARKING BRAKE 52
`
`S4
`
`
`
`TO START ENGINE 12
`
`
`
`PARKING BRAKE
`SWITCH ON ?
`
`
`
`YES
`
`RRST MOTOR 16 OPERATED
`
`S3
`
`5 of 27
`
`FORD 1417
`
`5 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10,1999
`
`Sheet 5 0f 16
`
`5,934,395
`
`ENGINE
`
`
`
`
`FIRST
`SECOND
`MOTOR/
`MOTOR/
`
`
`GENERATOR
`GENERATOR
`
`CONTROL
`CONTROL
`
`
` UNIT
`UNIT
`
`
`
`
`
`36
`
`.
`
`.
`
`38
`
`ELECTRICAL
`ENERGY
`
`FIG. 5
`
`363%?
`
`6 of 27
`
`FORD 1417
`
`6 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10, 1999
`
`Sheet 6 0f 16
`
`5,934,395
`
`FIGG
`
`ENGINE START CONTROL ROUTINE
`
`
`
`V m
`
`ENGINE START
`COMMAND ?
`
`
`
`YES
`
`FRICTION BRAKE 48
`ACTUATED
`
`02
`
`OS
`
`FIRST MOTOR 16 OPERATED
`TO START ENGINE 12
`
`
`
`
`FIG.7
`
`
`
` V R1
`
`ENGINE START
`COMMAND ?
`
`YES
`
`
`MOTORS 16 22 OPERATED
`TO START ENGINE 12
`
`
`WHILE PREVENTING
`VEHICLE DRIVE FORCE
`VARIATION
`
`
`R2
`
`7of27
`
`FORD 1417
`
`7 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10,1999
`
`Sheet 7 0f 16
`
`5,934,395
`
`42
`
`CONTROLLER
`
`VEHICLE SPEED
`DETECTING MEANS
`
`72
`
`78
`
`SHIFT POSITION
`DETECTING MEANS
`
`_
`
`.
`ST)-
`
`ACCELERATOR OPERATION
`DETECTING MEANS
`
`_
`
`82
`
`88
`
`38
`
`E
`
`DEVICE
`
`
`ELECTRICALLY
`
`HYDRAULIC
`
`UNIT OPERATED
`
`SECOND
`MOTOR/
`GENERATOR
`CONTROL
`
`FIRST
`MOTOR/
`GENERATOR
`CONTROL
`
`76
`
`FIG.8
`
`F 74
`
`8 of 27
`
`FORD 1417
`
`8 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10,1999
`
`Sheet 8 0f 16
`
`5,934,395
`
`ENGINE START CONTROL ROUTINE
`
`SAT
`
`0
`
`ENGINE START
`COMMAND?
`
`
`
`
`
`FIGS
`
`
`
`8A4
`
`YES
`SA2
`
`
`PARKING
`POSITION ?
`
`NEUTRAL
`N0
`
`POSITION ?
`
`
`
`
`
`
`8A7
`
`@“0
`
`YES
`
`8A8
`
`@”
`
`
`
`
`
`
`SECOND
`M/G 22
`CONTROLLED
`TO PREVENT
`VEHICLE
`DRIVE
`FORCE
`VARIATION
`
`FRICTION BRAKE
`48 OPERATED
`
`
`ENGINE STARTED
`BY FIRST MOTOR/
`
`GENERATOR 16
`
`
`
`SA3
`
`9 of 27
`
`FORD 1417
`
`9 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10,1999
`
`Sheet 9 0f 16
`
`5,934,395
`
`
`
`
`
`
`ELECTmc
`ENERGY
`STORAGE
`DEva
`LGML
`v LTAGE
`TYPE)
`
`
`
`
`
`
`UNIT
`FIG. 10
`
`FIRST
`MOTOR/
`GENERATOR
`CONTROL
`UNIT
`
`SECOND
`MOTOR/
`GENERATOR
`CONTROL
`
`ELECTRICAL
`ENERGY
`STORAGE
`
`10 of 27
`
`FORD 1417
`
`10 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10,1999
`
`Sheet 10 0f 16
`
`5,934,395
`
`FIG. 11
`
`STATE
`
`STATE
`
`STARTER
`
`E’EHJEE
`
`
`
`
`
`N (STOP)
`N (RUN)
`
`C) It?)_|O:3
`
`D (RUN)
`
`D (RUN)
`
`
`EREE
`(NON-LOAD)
`EREE
`FREE
`
`MECHANICAL
`ON
`PARKING LOCK
`FRICTION BRAKE ON “
`NO SPEC(3FIARLE(E3)ONTROL
`
`FREE
`
`FREE
`
`NO SPECIAL CONTROL
`
`' NO SPECIAL CONTROL
`
`MOTORING
`
`NO SPECIAL CONTROL
`
`
`
`
`
`
`
`11 of 27
`
`FORD 1417
`
`11 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10,1999
`
`Sheet 11 0f 16
`
`5,934,395
`
`FIG. 12
`
`ENGINE START
`COMMAND ?
`
`YES
`
`YES
`
`FIRST M/G 16
`IN OPERATION ?
`
`882
`
`NO
`
`STARTER 102 TURNED ON
`
`SB3
`
`12 of 27
`
`FORD 1417
`
`12 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10, 1999
`
`Sheet 12 0f 16
`
`5,934,395
`
`UNR
`
`HRST
`MOTOR/
`GENERATOR
`CONTROL
`UNR
`
`SECOND
`MOTOR/
`GENERATOR
`CONTROL
`
`ELECTWCAL
`ENERGY
`STORAGE
`
`DEWCE
`
`13of27
`
`FORD 1417
`
`13 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10,1999
`
`Sheet 13 0f 16
`
`5,934,395
`
`FIG. 14
`
`
`SEWER
`STATE
`STATE
`CLUTCH
`
`
`
`
`
`
`
`
`
`
`
`
`FORWARD -ORWARD-ROTATION _OTATION_ELEASED
`
`
`
`
`EgFT‘XVT/‘ISB
`LOCKED
`RELEASED
`
`
`P,N
`
`FORWARD
`
`FORWARD
`ROTATION
`CONTROL
`
`NO SPECIAL
`
`RELEASED
`ENGAGED
`
`
`
`
`
`LOCKED
`
`n ROTATION
`
`
`14 of 27
`
`FORD 1417
`
`14 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10,1999
`
`Sheet 14 0f 16
`
`5,934,395
`
`FIG. I5
`
`
`
`
`
`M ENGINE START
`
`COMMAND?
`
`
`
`YES
`
`802
`
`PARKING
`OR NEUTRAL
`POSITION ?
`
`YES
`
`NO
`
`CLUTCH112 RELEASED SCB
`
`OUTPUTCONTROLOF
`M/G16AND M/G 22
`
`.
`804
`
`805
`
`N0
`
`DRIVE
`POSITION?
`
`CLUTCH 112 ENGAGED
`
`ENGINE 12 STARTED
`BY FIRST M/G 16
`
`
`
`
`END
`
`15 of 27
`
`FORD 1417
`
`15 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10,1999
`
`Sheet 15 0f 16
`
`5,934,395
`
`
`
`
`ELECTmc
`ENERGY
`STORAGE
`DEWCE
`LOME
`v LTAGE
`TYPE)
`
`
`
`
`
`
`
`
`UNIT
`
`FIRST
`MOTOR/
`GENERATOR
`CONTROL
`UNIT
`
`SECOND
`MOTOR/
`GENERATOR
`CONTROL
`
`ELECTRICAL
`
`sEIIyERRACEYE
`
`DEVICE
`
`FIG. 16
`
`16 of 27
`
`FORD 1417
`
`16 of 27
`
`FORD 1417
`
`

`

`US. Patent
`
`Aug. 10,1999
`
`Sheet 16 0f 16
`
`5,934,395
`
`PK}. 17
`
`ENGINE START
`COMMAND ?
`
`YES
`
`
`
`
`
`SD2
`
`IMPOSSIBLE TO OPERATE
`
`MOTOR 16 OR MOTOR >
`
`TORQUE INSUFFICIENT?
`
`
`
`
`
`COMMANDING STARTER 102
`TO ASSlST MOTOR 16
`
`YES
`
` SD3
`
`17 of 27
`
`FORD 1417
`
`17 of 27
`
`FORD 1417
`
`

`

`5,934,395
`
`1
`HYBRID VEHICLE DRIVE SYSTEM HAVING
`TWO MOTOR/GENERATOR UNITS AND
`ENGINE STARTING MEANS
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`The present invention relates in general to a hybrid drive
`system for driving a motor vehicle, which has an engine and
`a motor/generator as drive power sources, and more par-
`ticularly techniques for starting the engine.
`2. Discussion of the Related Art
`
`There is known a hybrid drive system for a motor vehicle,
`which includes (a) an engine operated by combustion of a
`fuel, (b) a first motor/generator, (c) a distributing mechanism
`for mechanically distributing an output of the engine to the
`first motor/generator and an output member, (d) a second
`motor/generator whose rotary force is transferred to a power
`transmitting path between the output member and a drive
`wheel of the motor vehicle. An example of such a hybrid
`drive system is disclosed in JP-A-50-30223, wherein the
`distributing mechanism consists of a planetary gear device,
`and the rotary force of the second motor/generator is trans-
`ferred to the output member. In this hybrid drive system, the
`first motor/generator is used exclusively as an electric gen-
`erator to charge an electric energy storage device such as a
`battery with an electric energy, while the second motor/
`generator is used exclusively as an electric motor for driving
`the vehicle, either alone or in cooperation with the engine.
`Generally, an electric generator may be used as an electric
`motor, while an electric motor may be used as an electric
`generator. In this sense, the term “motor/generator” is used
`herein.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`The above-identified publication JP-A-50-30223 does not
`refer to a manner of starting the engine.
`
`35
`
`SUMMARY OF THE INVENTION
`
`It is an object of the present invention to provide a hybrid
`vehicle drive system of mechanical distribution type which
`has an engine, a first motor/generator, a distributing mecha-
`nism and a second motor/generator, and which has engine
`starting means for suitably starting the engine.
`The above object may be achieved according to a first
`aspect of this invention, which provides a hybrid drive
`system for a motor vehicle, comprising:
`(a) an engine
`operated by combustion of a fuel; (b) a first motor/generator;
`(c) a distributing mechanism for mechanically distributing
`an output of the engine to the first motor/generator and an
`output member operatively connected to a drive wheel of the
`motor vehicle; (d) a second motor/generator whose rotary
`force is transferred to a power transmitting path between the
`output member and the drive wheel; and (e) engine starting
`means for operating the first motor/generator to crank the
`engine through the distributing mechanism,
`for thereby
`starting the engine.
`In the hybrid drive system constructed according to the
`first aspect of this invention, the engine is cranked by the
`first motor generator through the distributing mechanism,
`whereby the engine is started by the first motor/generator.
`The present hybrid drive system does not require an exclu-
`sive engine starter, and is accordingly available at a reduced
`cost owing to reduction in the number of the required
`components.
`In the present hybrid drive system, an electrical energy
`storage device can be charged by the first motor/generator,
`which is operated as an electric generator by an output of the
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`engine transferred thereto through the distributing mecha-
`nism. To start or fire the engine, the first motor/generator is
`operated as an electric motor to crank the engine through the
`distributing mechanism. However, the first motor/generator
`may be used as a drive power source for driving the vehicle.
`On the other hand,
`the second motor/generator is used
`primarily as an electric motor or a drive power source for
`driving the vehicle, either alone or in cooperation with the
`engine. The second motor/generator may be used as an
`electric generator for charging the electric energy storage
`device by regenerative braking, while applying a brake to
`the vehicle, like an engine brake.
`The distributing mechanism is preferably a gear type
`mechanism having three rotary members, such as a planetary
`gear device or a bevel gear type differential gear device, and
`may include clutches as needed, for example, a clutch for
`selective connection and disconnection between the engine
`and the first motor/generator, and a clutch for selective
`connection and disconnection between two of the three
`rotary members. Where a planetary gear device having a sun
`gear, a carrier and a ring gear is used as the distributing
`mechanism, the sun gear, carrier and ring gear are connected
`to the appropriate ones of the engine, first motor/generator
`and output member. For instance, the carrier is connected to
`the engine, while the sun and ring gears are connected to the
`first motor/generator and the output member, respectively. A
`damper including an elastic member such as a spring or
`rubber member may be disposed between the engine and the
`distributing mechanism, for absorbing a variation in the
`rotary motion of the engine. An appropriate power trans-
`mitting mechanism such as a gear device may be disposed
`between the distributing mechanism and the engine, and/or
`between the distributing mechanism and the first motor/
`generator.
`The second motor/generator is adapted to transfer its
`rotary motion or force to the power transmitting path
`between the output member and the vehicle drive wheel. A
`single second motor/generator may be provided for the
`output member. Alternatively, two or more second motor/
`generator units may be provided for a plurality of vehicle
`drive wheels, respectively. In this latter case, two or more
`assemblies each including the distributing mechanism, first
`motor/generator and second motor/generator are provided
`for respective vehicle drive wheels, while a single engine is
`provided for these assemblies. A clutch may be provided
`between the second motor/generator and the output member
`or any member operatively connected to the drive wheel.
`According to one preferred form of the first aspect of the
`invention, the hybrid drive system further comprises drive
`force variation restricting means for restricting a variation in
`a vehicle drive force due to a reaction force which acts on
`
`the output member upon starting of the engine by the engine
`starting means.
`When the engine is cranked by the first motor/generator
`through the distributing mechanism, a reaction force may act
`on the output member due to a resistance (e.g., frictional
`resistance) to rotation of the engine, or an output of the
`engine or first motor/generator (operating as the motor) may
`act on the output member immediately after starting or firing
`of the engine, whereby there may arise a variation in the
`drive force driving the vehicle, unexpectedly to the vehicle
`operator and passengers. In the light of this phenomenon, the
`drive force variation restricting means is provided according
`to the above preferred form of the hybrid drive system, for
`the purpose of at least restricting such possible variation of
`the vehicle drive force upon starting of the vehicle, which
`would otherwise give a discomfort to the vehicle operator
`and passengers.
`
`18 of27
`
`FORD 1417
`
`18 of 27
`
`FORD 1417
`
`

`

`5,934,395
`
`3
`In a first advantageous arrangement of the above preferred
`form of the hybrid drive system, the drive force variation
`restricting means comprises parking lock means for
`mechanically locking the drive wheel by manipulation of an
`operator’s controlled operating member.
`The parking lock means may include a parking brake
`which is operated by the operator’s controlled operating
`member such as a parking brake lever, to mechanically lock
`the drive wheel of the vehicle. Where the hybrid drive
`system includes shift position selecting means such as a shift
`lever having a forward-drive position (D), a reverse-drive
`position (R), and a parking position (P), the parking lock
`means may include a mechanical parking lock mechanism
`which is adapted to mechanically lock the vehicle (hold the
`vehicle stationary) when the shift position selecting means is
`operated to the parking position. The drive force variation
`restricting means preferably include means for checking if
`the parking lock means is in the operated position for
`mechanically locking the vehicle, prior to an operation of the
`engine starting means, and means for prompting the vehicle
`operator to operate the parking lock means if the vehicle is
`not mechanically locked by the parking lock means.
`In a second advantageous arrangement, the drive force
`variation restricting means comprises engine start motor
`control means for controlling the second motor/generator so
`as to offset the variation in the vehicle drive force upon
`starting of the engine by the engine starting means.
`The engine start motor control means is adapted to control
`the torque (including regenerative braking torque) of the
`second motor/generator, so as to absorb or prevent a varia-
`tion in the vehicle drive force, even when the output member
`is subjected to a reaction force due to a resistance (e.g.,
`frictional resistance) to rotation of the engine, or due to an
`influence of an output of the engine or first motor/generator
`immediately after starting or firing of the engine. The engine
`start motor control means is capable of restricting the
`vehicle drive force variation even when the engine is started
`during running of the vehicle. For instance, the first motor/
`generator may be controlled by the engine start motor
`control means during running of the vehicle by the second
`motor/generator as a single drive power source. In this case,
`the first motor/generator placed in a non-load or free state is
`rotated in the reverse direction such that its regenerative
`braking torque is controlled by the engine start motor control
`means, or a torque applied to the first motor/generator in the
`forward direction is controlled by the engine start motor
`control means, whereby the engine can be cranked and
`started through the distributing mechanism. In this instance,
`a portion of the output of the second motor/generator is
`consumed by rotation of the engine. Therefore, the second
`motor/generator is operated to provide a total output which
`is larger than the power required for driving the vehicle, and
`the engine is driven by surplus power which is equal to the
`total output of the second motor/generator minus the
`required power for driving the vehicle. Thus, the engine start
`motor control means can restrict a possible variation in the
`vehicle drive force upon starting of the engine during
`running of the vehicle. The engine start motor control means
`may be desirably adapted to reduce the output of the second
`motor/generator when the output of the engine temporarily
`is transferred to the output member immediately after the
`starting or firing of the engine.
`Thus, the engine start motor control means according to
`the second advantageous arrangement is adapted to operate
`the second motor/generator for offsetting or absorbing the
`drive force variation upon starting of the engine, and is
`effective not only when the vehicle is stationary, as in the
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`
`above first advantageous arrangement (and in a third advan-
`tageous arrangement which will be described), but also
`when the vehicle is running. The engine start motor control
`means according to this second advantageous arrangement
`simply controls the second motor/generator to restrict the
`drive force variation, and does not require the vehicle
`operator to manipulate any operator’s controlled operating
`member as required in the first advantageous arrangement
`using the parking lock means. Accordingly, the engine start
`motor control means reduces the operator’s load upon
`starting of the engine, and the hybrid drive system is simpler
`in construction and more economical to manufacture than
`
`the hybrid drive system according to the third advantageous
`arrangement using the engine start braking means.
`In a third advantageous arrangement,
`the drive force
`variation restricting means comprises engine start braking
`means for automatically mechanically braking the drive
`wheel prior to starting of the engine by the engine starting
`means.
`
`The engine start braking means according to the above
`third advantageous arrangement is adapted to automatically
`brake the drive wheel of the vehicle upon starting of the
`engine. Thus, the vehicle operator’s load is smaller in the
`present third advantageous arrangement than in the first
`advantageous arrangement which requires the vehicle opera-
`tor to manipulate the operating member for operating the
`parking lock means. Further, the engine start braking means
`is simpler in its control and permits more stable locking of
`the vehicle drive wheel than the engine start motor control
`means adapted to control the second motor/generator. This
`engine start braking means is operable even when the
`electric energy stored in an electric energy storage device is
`insufficient (even when this insufficiently charged storage
`device is charged by the motor/generator by operation of the
`engine), or even when the hybrid drive system is placed in
`the neutral or parking position in which the second motor/
`generator cannot be used to restrict the vehicle drive force
`variation. Where the second motor/generator and the drive
`wheel are mechanically directly connected to each other, the
`hybrid drive system is generally adapted to inhibit, for
`safety, the operation of the second motor/generator (or hold
`the second motor/generator in the non-load or free state)
`when the drive system is placed in the neutral or parking
`position.
`The engine start braking means may include a hydrauli-
`cally operated or other wheel brake provided for a vehicle
`drive wheel or idler wheel, or a hydraulically operated or
`other friction brake provided in a power transmitting path
`terminating at
`the vehicle drive wheel. In this case, the
`engine start braking means includes a hydraulic circuit
`having a solenoid-operated switching valve or an electrically
`operated pump, and is adapted to control the switching valve
`or operate the pump for delivering a pressurized fluid to
`actuate the wheel brake or friction brake, prior to starting of
`the engine, for applying brake to the drive wheel and/or idler
`wheel of the vehicle to thereby hold the vehicle stationary.
`The engine start braking means may use any other type of
`brake adapted to produce a braking force. Where the vehicle
`is provided with a parking lock mechanism which is actu-
`ated to lock the vehicle when the hybrid drive system is
`placed in the parking position, it is desirable to actuate the
`engine start braking means to hold the vehicle stationary,
`when the engine is started while the drive system is placed
`in the drive position (forward-drive or reverse-drive position
`D, R) or the neutral position (NO).
`According to a fourth advantageous arrangement of the
`above preferred form of the invention including the drive
`
`19 of27
`
`FORD 1417
`
`19 of 27
`
`FORD 1417
`
`

`

`5,934,395
`
`5
`force variation restricting means, means is provided for
`inhibiting an operation of the drive force variation restricting
`means when a running speed of the motor vehicle is higher
`than a predetermined threshold.
`In the above arrangement, the engine is started by the
`engine starting means without operation of the drive force
`variation restricting means when the vehicle speed is higher
`than the predetermined threshold. Although some variation
`in the vehicle drive force may arise due to a reaction force
`upon starting of the engine during running of the vehicle at
`a relatively high speed, an influence of this drive force
`variation is smaller than when the vehicle is stationary or
`running at a relatively low speed. That is, the degree of
`discomfort given to the vehicle operator by the drive force
`variation is comparatively small when the vehicle is running
`at a relatively high speed. The threshold of the vehicle speed
`is determined so that a variation in the vehicle drive force
`
`due to a reaction force upon starting of the engine during
`running of the vehicle will not give the vehicle operator a
`discomfort upon starting of the engine by the engine starting
`means.
`
`The object indicated above may also be achieved accord-
`ing to a second aspect of this invention, which provides a
`hybrid drive system for a motor vehicle, comprising: (a) an
`engine operated by combustion of a fuel; (b) a first motor/
`generator; (c) a distributing mechanism for mechanically
`distributing an output of the engine to the first motor/
`generator and an output member operatively connected to a
`drive wheel of the motor vehicle;
`(d) a second motor/
`generator whose rotary force is transferred to a power
`transmitting path between the output member and the drive
`wheel; (e) an engine starter motor for starting the engine;
`and (f) engine starting means for operating the engine starter
`motor to crank the engine without a rotary motion being
`transferred to the distributing mechanism and while the first
`motor/generator is placed in a non-load state, for thereby
`starting the engine.
`In the hybrid drive system constructed according to the
`second aspect of this invention, the engine is started by the
`engine starter motor, which is exclusively provided for
`starting the engine. When the engine is started,
`the first
`motor/generator is placed in the non-load state in which the
`first motor/generator is freely rotatable. When the engine is
`cranked by the engine starter motor, the first motor/generator
`is rotated, whereby the output member and the drive wheel
`are prevented from being subjected to a drive force.
`Accordingly, the present hybrid drive system is effective to
`prevent a possible variation in the vehicle drive force upon
`starting of the engine, and prevent a discomfort which would
`be otherwise given to the vehicle operator and passengers
`upon starting of the engine not only when the vehicle is
`running but also when the vehicle is stationary.
`The engine starter motor is preferably adapted to be
`operated by an electric energy supplied from an electric
`energy storage device of low-voltage type (e.g., 12V) as
`generally provided on a common engine-driven vehicle. In
`this case,
`the electric energy storage device is desirably
`provided with external terminals for connection through a
`booster cable to an electric energy storage device on an
`engine-driven vehicle so that the insufficiently charged stor-
`age device of the hybrid drive system can be charged.
`Therefore, the engine starter motor can be operated to start
`the engine after the insufficiently charged storage device is
`sufficiently charged. Thus, the first motor/generator can be
`operated as the electric generator by the started engine, to
`charge an electric energy storage device of high-voltage type
`which is provided for operating the second motor/generator
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6
`to drive the vehicle. The low-voltage storage device used for
`the engine starter motor may also be used as a power source
`for operating an air conditioner or other device optionally
`provided on the vehicle. Further, the low-voltage storage
`device may be adapted to be charged by the first motor/
`generator through a voltage converter device.
`The engine starter motor need not be necessarily operated
`upon starting of the engine. That is, the engine starter may
`be operated only when the high-voltage storage device
`indicated above is insufficiently charged and cannot operate
`the first motor/generator. In this case, the engine is started by
`the engine starter motor while the first motor/generator is
`held in the non-load condition. The engine starter motor may
`be used as a secondary drive source for cranking the engine,
`as needed, namely,
`to assist the first motor/generator as
`needed for starting the engine.
`The object indicated above may also be achieved accord-
`ing to a third aspect of this invention, which provides a
`hybrid drive system for a motor vehicle, comprising: (a) an
`engine operated by combustion of a fuel; (b) a first motor/
`generator; (c) a distributing mechanism for mechanically
`distributing an output of the engine to the first motor/
`generator and an output member operatively connected to a
`drive wheel of the motor vehicle;
`(d) a second motor/
`generator whose rotary force is transferred to a power
`transmitting path between the output member and the drive
`wheel of the motor vehicle; (d) a clutch disposed between
`the output member and the drive wheel and having an
`engaged position for connecting the output member to the
`drive wheel and a released position for disconnecting the
`drive wheel from the output member; and (e) engine starting
`means for operating at least one of the first motor/generator
`and the second motor/generator to crank the engine while
`the clutch is placed in the released position, for thereby
`starting the engine.
`In the hybrid drive system constructed according to the
`third aspect of the invention, the engine is started by first
`releasing the clutch disposed between the output member
`and the vehicle drive wheel for disconnecting the output
`member from the drive wheel, and then operating at least
`one of the first motor/generator and the second motor/
`generator. Therefore, this hybrid drive system does not give
`the vehicle operator and passengers a discomfort due to a
`variation in the vehicle drive force upon starting of the
`engine, if the engine is started when the vehicle is stationary.
`During running of the vehicle, the engine is generally started
`with the clutch held in the engaged position, but may be
`started by temporarily releasing the clutch.
`The hybrid drive system according to the third aspect of
`the invention may further comprise an engine starter motor
`for starting the engine, and motor assisting means for
`operating the engine starter to assist the first motor/generator
`and/or the second motor/generator to start the engine when
`the motor vehicle is in a predetermined condition, for
`instance, when the engine cannot be started by the first
`motor/generator and/or the second motor/generator.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The above and optional objects, features, advantages and
`industrial and technical significance of the present invention
`will be better understood by reading the following detailed
`description of presently preferred embodiments of the
`invention, when considered in connection with the accom-
`panying drawings, in which:
`FIG. 1 is an elevational view in cross section of a hybrid
`drive system according to one embodiment of this invention;
`
`20 of 27
`
`FORD 1417
`
`20 of 27
`
`FORD 1417
`
`

`

`5,934,395
`
`7
`FIG. 2 is a schematic view illustrating the hybrid drive
`system of FIG. 1;
`FIG. 3 is a block diagram indicating a control arrange-
`ment of the hybrid drive system of FIG. 1;
`FIG. 4 is a flow chart illustrating an operation of the
`hybrid drive system of FIG. 1 to start an engine;
`FIG. 5 is a schematic view corresponding to that of FIG.
`2, illustrating a hybrid drive system according to a second
`embodiment of the invention;
`FIG. 6 is a flow chart illustrating an operation of the
`hybrid drive system of FIG. 5 to start an engine;
`FIG. 7 is a flow chart illustrating an operation of a hybrid
`drive system to start an engine according to a third embodi-
`ment of the invention;
`FIG. 8 is a schematic view illustrating a fourth embodi-
`ment of this invention;
`illustrating an engine starting
`FIG. 9 is a flow chart
`operation in the embodiment of FIG. 8;
`FIG. 10 is a schematic view illustrating a fifth embodi-
`ment of this invention;
`FIG. 11 is a view for explaining a relationship between the
`position of a shift lever, and the operating states of motor/
`generators and an engine starter, in starting an engine in the
`embodiment of FIG. 10;
`FIG. 12 is a flow chart illustrating an engine starting
`operation in the embodiment of FIG. 10;
`FIG. 13 is a schematic view illustrating a sixth embodi-
`ment of the invention;
`FIG. 14 is a view for explaining a relationship between
`the shift lever position and the operating states of motor/
`generators and engine starter, in starting an engine in the
`embodiment of FIG. 13;
`FIG. 15 is a flow chart illustrating an engine starting
`operation in the embodiment of FIG. 13;
`FIG. 16 is a schematic view illustrating a seventh embodi-
`ment of the invention; and
`FIG. 17 is a flow chart illustrating an engine starting
`operation in the embodiment of FIG. 16.
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`Referring first to the cross sectional view of FIG. 1 and the
`schematic view of FIG. 2, there is shown a hybrid drive
`system 10 for a motor vehicle, which is constructed accord-
`ing to a first embodiment of the present invention. The
`hybrid drive system 10 includes: an engine 12 such as an
`internal combustion engine, which is operated by combus-
`tion of a fuel; a damper 14 of spring type adapted to absorb
`a fluctuation in the rotary motion of the engine 12; a first
`motor/generator 16; an output member 18; a distributing
`mechanism 20 of planetary gear type which receives an
`output of the engine 12 through the damper 14 and which
`mechanically distributes the received engine output to the
`first motor/generator 16 and the output member 18; and a
`second motor/generator 22 whose rotary motion or force is
`transferred to the outpu