VWGoA - Ex. 1006
`Volkswagen Group of America, Inc. - Petitioner
`
`1
`
`

`
`U.S. Patent
`
`Dec. 16,1997
`
`Sheet 1 of 11
`
`5,697,466
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`2
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`U.S. Patent
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`Dec. 16, 1997
`
`Sheet 2 of 11
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`5,697,466
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`

`
`U.S. Patent
`
`Dec. 16,1997
`
`Sheet 3 of 11
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`5,697,466
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`48
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`POWER CIRCUIT
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`SELF-DIAGNOSIS CIRCUIT
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`MOTOR CONTROLLER
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`SELF*DIAGNOSIS CIRCUIT
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`CIRCUIT MALFUNCTION STATE
`DIAGNOSIS CIRCUIT
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`ACCELERAJUR PEDAL OPERATION DEGREE €9--
`|._ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ __ _ _ _ _ _.—
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`OUTPUT sum TORQUE —————————-3
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`BRAKE slam-————
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`MOTOR FAULT
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`ENGINE STARTER‘
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`MOTOR DRIVE SIGNAL
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`DRIVER'S OPERATION
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`4
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`

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`U.S. Patent
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`Dec. 16, 1997
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`Sheet 4 of 11
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`5,697,466
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`

`
`U.S. Patent
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`Dec.16, 1997
`
`Sheet 6 of 11
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`5,697,466
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`FlG.7
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` 47
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`~l___
`BATTERY RESIDUE DETECTUR /I
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` ---BATTERY RESIDUE
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`
`7
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`

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`U.S. Patent
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`Dec. 16, 1997
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`Sheet 7 of 11
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`5,697,466
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`FlG.8
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`TERHINALVOLTAGEAFTER5SECONDS[\/J
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`DISCHARGE DEGREE
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`RELATIVEDENSITYINDISCHARGING
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`1D1SCHARGE DURATION
`
`[11]
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`8
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`

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`U.S. Patent
`
`Dec. 16, 1997
`
`Sheet 3 of 11
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`5,697,466
`
`FlG.|O
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`1
`ENGINE/MITOR
`DRIVE HIDE ‘f’
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`ENGINE DRIVE MJDE
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`TRAVELING SPEED
`
`V [km/h]
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`9
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`

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`U.S. Patent
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`Dec. 16, 1997
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`Sheet 9 of 11
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`F|G.|2
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`ACCELERATORPEDALOPERATIONDEGREEeaEx)
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`ENGINE DRIVE MODE
`
`TRAVELING spann
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`(km/h]
`
`10
`
`10
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`

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`U.S. Patent
`
`Dec. 16, 1997
`
`Sheet 10 of 11
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`5,697,466
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`|8b
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`26
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`ENGINE
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`11
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`

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`U.S. Patent
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`Dec. 16, 1997
`
`Sheet 11 of 11
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`5,697,466
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`FlG.l6
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`PRIOR ‘ART
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`
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`TEMPERATURE
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`—-—'~— HIGH
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`12
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`12
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`

`
`1
`HYBRID VEHICLE
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`5 ,697,466
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`2
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`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`This invention relates to a hybrid vehicle.
`2. Description of the Related Art
`A general use vehicle conventionally has an internal
`combustion engine using gasoline to rotate driving wheels
`via an transmission unit. either automatic or manual.
`wherein the rotational speed of the engine is changed as
`demanded The internal combustion engine naturally burns
`a mixed gas consisting of gasoline and air to obtain torque
`energy.
`thereby generating noise and exhaust gas. both
`detrimental to the environment.
`
`An electric vehicle. using an electric motor instead of the
`above-mentioned internal combustion engine. eliminates the
`above-mentioned noise and exhaust gas. The electric vehicle
`carries the electric motor accompanied by a battery to rotate
`the driving wheels without noise or exhaust gas. However.
`an electric vehicle having a limited travel distance on one
`battery charge is of no practical use. Accordingly. a hybrid
`vehicle wherein both the internal combustion engine and the
`electric motor are effectively used has been proposed (see.
`Japanese Patent Laid-open No. Sho 59-20442 and U.S. Pat.
`No. 4.533.011).
`However. when a motor driving system. essentially con-
`sisting of the electric motor and the battery. develops trouble
`in one of the hybrid vehicles referred to above. the vehicle
`can not depend upon the electric motor for travel. Such
`trouble may occur when the electric current is supplied to the
`coil in the electric motor becomes so excessive that the
`copper wire and iron core generate heat and electrical
`resistance thereby increases in the copper wire.
`FIG. 16 shows a correlation between the temperature and
`the resistance in copper wire. A temperature hike from t1 to
`t2 in the copper wire used in the electric motor results in an
`increase of the electric resistance from R] to R2 as shown.
`thus rendering the motor inefiective because of energy
`losses resulting from heat generation and melting of the
`coating of the wire to short-circuit or break down the motor.
`The electric motor used in the conventional hybrid vehicle
`also stops operation when electric power stored in the
`battery (hereinafter referred to as “battery residual charge”)
`is completely consumed.
`An object of the present invention is to provide an
`improved hybrid vehicle which continues travelling
`comfortably. so as to overcome the disadvantages in the
`conventional hybrid vehicle, even if the motor driving
`system used therein suddenly develops some problem in
`operation.
`
`SUMMARY OF THE INVENTION
`
`To attain the above objective. the present invention pro-
`vides an improved hybrid vehicle having an internal com-
`bustion engine and an electric motor with its output con-
`nected to an output axle. A clutch selectively connects the
`internal combustion engine to the output axle and a hydrau-
`lic power transmission is lrovided between the clutch and
`the internal combustion engine. A drive power share com-
`puting means apportions the drive power between the engine
`and the motor and is responsive to a signal from detecting
`means for detecting a malfunction of the motor. A first
`control means releases the clutch when the vehicle is driven
`by the motor and a second control means efl‘ects engagement
`of the clutch for driving by the engine even when the vehicle
`
`is running with power from the motor when the detecting
`means detects a malfunction of the motor.
`
`The hybrid vehicle may also have a third control means
`for interrupting the motor during the driving state thereof
`when the detecting means detects a malfunction of the
`motor.
`
`10
`
`Incidentally, the malfunction state may originate either in
`the motor in a low electrical residual charge of the battery or
`in the motor drive assembly for the motor.
`The output axle can be provided with a transmission unit
`after the motor.
`
`The hydraulic power transmission can be a torque con-
`vertor including a pump impeller. a turbine runner and a
`stator.
`’
`
`The hydraulic power transmission may further have a
`lock-up clutch for a direct connection of the input and output
`shafts.
`
`The drive power share computing means is adapted to
`operate responsive to travelling speed and degree of throttle
`opening.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`30
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`35
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`45
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`55
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`FIG. 1 is a schematic diagram of one embodiment of the
`present invention;
`FIG. 2 is a block diagram depicting the CPU of FIG. 1;
`FIG. 3 is a block diagram illustrating motor fault detec-
`tion;
`
`FIG. 4 is a drive mode map which may be used in the first
`embodiment;
`FIG. 5 is a graphical representation showing the relation-
`ship between motor temperature and accelerator pedal
`operation in the first embodiment;
`FIG. 6 is a graphical representation showing the relation-
`ship between motor temperature and changeover traveling
`speed in the first embodiment;
`FIG. 7 is a block diagram showing a battery residual
`charge detector system;
`FIG. 8 is a graphical representation showing the relation-
`ship between discharge current.
`terminal voltage after 5
`seconds and the battery residual charge;
`FIG. 9 is a graphical representation showing the relation-
`ship between discharge duration and relative density in
`discharging;
`FIG. 10 depicts a first drive mode map utilized when the
`motor drive assembly is in good order;
`FIG. 11 depicts a second drive mode map;
`FIG. 12 depicts a third drive mode map;
`FIG. 13 depicts a power train system without a transmis-
`sion unit;
`FIG. 14 depicts a power train system with a transmission
`unit;
`
`FIG. 15 depicts a power train system with two transmis-
`sion units; and
`FIG. 16 is a graphical representation of a correlation
`between temperature and electrical resistance in copper
`wire;
`
`Still othe1' objects and advantages of the present invention
`will become readily apparent to those skilled in this art from
`the following detailed description. wherein only the pre-
`ferred embodiments of the invention are shown and
`described. simply by way of illustration of the best mode
`contemplated for carrying out the invention. As will be
`realized. the invention is capable of other and dilferent
`
`65
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`13
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`5,697,466
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`3
`embodiments. and its details are capable of modifications in
`various obvious respects. all without departing from the
`invention. Accordingly. the drawings and description are to
`be regarded as illustrative in nature. and not as restrictive.
`DETAILED DESCRIPTION OF THE
`PREFERRED ENIBODID/[ENT(S)
`
`The most prefe1'red embodiment of the present invention
`will now be described with reference to the drawings.
`FIG. 1 is a schematic and block diagram of the entire first
`embodiment of the present invention. It should be under-
`stood that some structural elements are explained in con-
`nection with latter embodiments.
`
`10
`
`At the beginning of the detailed description of the pre-
`ferred embodiments, a train system in a hybrid vehicle will
`be explained, as is used in all of the embodiments described
`in the present application.
`In the drawing. the reference numeral 11 is an internal
`combustion engine which is selectively operated. 12 is an
`electric motor which is selectively operated, 14 is a difler-
`ential gear unit. 15 is a torque convertor used as a hydraulic
`power transmission. C is a clutch rotating into engagement
`with the internal combustion engine 11, and 16 is a planetary
`gear unit. The planetary gear unit 16 is a single planetary
`type gear unit comprising a ring gear R. a pinion P. a sun
`gear S. and a carrier CR carrying the pinion P. B is a brake
`selectively meshing with the sun gear S and F is a one-way
`clutch. The planetary gear unit 16, the brake B and the
`one-way clutch F define a transmission unit 18.
`The reference numeral 19 indicates a driving unit case in
`which the electric motor 12. the differential gear unit 14. the
`torque convertor 15. the clutch C. and the transmission unit
`18 are all housed together. The reference numeral 20 indi-
`cates a drive shaft for transmitting rotation at a reduced
`speed through the differential gear unit 14 to one driving
`wheel.
`
`The torque convertor 15 is defined by a pump impeller
`directly connected to an output shaft 22 extending from the
`engine 11. a trnbine runner connected to an output shaft 23,
`a stator located intennediate the pump impeller and the
`turbine runner, and a lock-up clutch arranged to rotate
`concurrently with the turbine runner. When the operat:ion of
`the lock-up clutch couples the wall of the case with the
`output shaft 22 via a frictional material, the two shafts 22
`and 23 rotate integrally. Otherwise. when the lock-up clutch
`is released. the torque convertor 15 functions as a conven-
`tional
`torque convator to transmit rotational power in
`accordance with relative rotation between the pump impella
`and the turbine runner. The lock-up clutch is essentially
`maintained in its engaged state continuously to prevent
`power loss due to slip in the convertor except when the
`clutch C is activated to connect the engine 11 and the electric
`motor 12.
`
`20
`
`30
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`35
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`45
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`Numeral 24 indicates an input shaft for the transmission
`unit 18. 25 is an output shaft for the transmission unit 18 and
`26 is an output shaft for the elecnic motor 12. The output
`shaft 26 is arranged to rotate concurrently with the output
`shaft 25.
`
`55
`
`It can be seen from the drawing that the electric motor 12
`is defined by a magneto stator 12a fixed on the driving unit
`case 19. a stator coil 12!: wound around the magneto stator
`12a and a rotor 12c connected with the output shaft 26. As
`the stator coil 12b receives the electrical power. the rotor 12c
`begins to rotate.
`The rotational power generated by the internal combus-
`tion engine 11 and the electric motor 12 is transferred to a
`counta drive gear 31.
`
`65
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`4
`
`In parallel with the output shaft 26. is a counter drive shaft
`32 which carries a counter driven gear 33 meshing with the
`counter drive gear 31 so as to transmit the rotation of the
`counter drive gear 31 to an output gear 34.
`The rotation of the output gear 34 causes rotation of a
`large output gear 35 engaged by the gear 34. As can be seen
`from the drawing. the number of teeth of the gear 35 is
`greater than the number of teeth of the gear 34 to provide a
`final speed reduction. The rotation of the gear 35 is further
`transmitted to the differential gear unit 14 to rotate the two
`drive shafts 20 laterally extending therefrom in opposite
`directions.
`in the hybrid vehicle
`As has been mentioned above.
`according to the present invention. there are three possible
`modes for powering the vehicle. the first one being an engine
`drive mode in which the vehicle runs only by means of the
`internal combustion engine 11, the second one being an
`electric motor drive mode in which the vehicle runs only by
`means of the electric motor 12 and the third one being an
`enginelmotor drive mode in which the engine 11 and the
`motor 12 are used together.
`When the vehicle is driven by means of the internal
`combustion engine in the engine drive mode. the rotational
`power of the engine 11 is transmitted to the torque convertor
`15 via the output shaft 22 and further transmitted to the
`clutch C via the output shaft 23. As the clutch C is engaged,
`the rotation of the output shaft 23 is transmitted to the carrier
`CR in the planetary gear unit 16 via the input shaft 24.
`In the planetary gear unit 16. as the brake B is released,
`the one-way clutch F is locked up by the rotation of the
`carrier CR whereby the rotation of the input shaft 24 is
`directly forwarded to the output shafts 25 and 26. When the
`brake B is engaged, the sun gear S stops its rotation. so that
`accelerated rotation speed from the ring gear R to the output
`shafts 25. 26 is generated to rotate the counter drive gear 31.
`The rotating counter drive gear 31 rotationally drives the
`counter drive shaft 32 via the counter driven gear 33. Then.
`the rotation of the shaft 32 is finally transmitted to the final
`speed reduction system defined by the output gear 34 and the
`large output gear 35 to move the vehicle at a controlled
`speed. In this state. the hybrid vehicle is run by only the
`power generated by the internal combustion engine.
`Next. in the motor drive mode without using the engine
`11, the torque generated by the motor 12 is transferred to the
`counter drive gear 31 via the output axle 26. In this state. the
`hybrid vehicle according to the present invention is moved
`only by the electric motor 12.
`When the vehicle is in the engine-Jmotor drive mode
`wherein both the engine 11 and the motor 12 are operated
`and the clutch C is activated, the vehicle can start and keeps
`moving, even when the motor 12 and a motor controller 49
`develop trouble. by power from the internal combustion
`engine.
`As has been mentioned. there are three modes. that is the
`engine drive mode. the motor drive mode and the engind
`motor drive mode, which are selected in a central processing
`unit (CPU) 58 according to circumstances. Generally, as the
`travelling speed v is low and the degree of accelerator pedal
`operation 6 is also low, the vehicle moves in the motor drive
`mode. When the speed v is high and the degree of accel-
`erator pedal operation degree 6 is low. the vehicle moves in
`the engine drive mode. And when the speed v is low and the
`degree of accelerator pedal operation 9 is high. the vehicle
`moves in the engine./motor drive mode. The CPU has
`memories such as RAM and ROM. the ROM being used to
`store several drive mode maps defining running ranges for
`the respective drive modes.
`
`14
`
`14
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`

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`5,697,466
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`5
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`If the motor drive assembly defined by the motor 12,
`battery 47, power circuit 48 and motor cont:roller 49 mal-
`functions due to some reason, the vehicle can not cnntinue
`to move in the motor drive mode. Such a problem tends to
`menu" when the magneto stator 12:: is abnonnally heated and
`the electrical resistance in the copper wire increases as
`excessive electric power is supplied to the stator coil 12b to
`operate the motor 12 to comply with a heavy duty travel
`demand.
`
`5
`
`6
`circuit for the power circuit 48. The self-diagnosis circuit
`48a comprises a circuit malfunction state diagnosis circuit
`and a disconnection/short-circuiting state diagnosis circuit.
`The reference numeral 49 indicates the motor controller and
`49a is the self-diagnosis circuit for the motor controller 49.
`The self-diagnosis circuit 49a also comprises a circuit
`malfunction state diagnosis circuit and a disconnection!
`short-circuiting state diagnosis circuit
`It can be seen from the drawing that the motor fault
`detector 56 receives signals from the self-diagnosis circuit
`48a indicating any unusual state of the power circuit 48 and
`from the self-diagnosis circuit 49a indicating any unusual
`state of the motor controller 49. The motor fault detector 56
`
`is further adapted to receive signals representative of torque
`of the output shafi 26, brake, travelling speed v, the degree
`of accelerator pedal operation 9 and the motor drive to thus
`determine whether the motor 12 is in a state of malfunction
`or not.
`
`If the drive command value for the electric power to the
`motor 12 depending upon signals for the motor drive is D
`and if the preliminary set value for same is DA.
`the
`following expression is obtained In this state. the brake
`pedal is not worked.
`D>=DA
`
`When comparing the actual travelling speed v with the
`preliminary set speed vA.
`the following expression is
`obtained as an indication that the motor 12 is in a state of
`malfunction.
`v<vA
`
`In a malfunction, for example. DA can be l0O(%) and vA
`can be 1(km/h).
`Furthermore, when the actual degree of accelerator pedal
`operation 6 is cnmpared with the predetermined value 9A.
`the following expression can be obtained In this state. the
`brake pedal is not worked
`6>=6A may mean a malfunction of the motor 12. In an
`example of such a status for BA and vA. BA can be 100(%)
`and vA can be 1(km/h).
`Otherwise, if the torque of the output shaft 26 is extremely
`low relatively, the driver may note a malfunction of the
`motor 12. When a malfunction of the motor 12 is detected.
`the motor fault detector 56 sends a signal to the CPU 58 to
`indicate that the motor 12 is out of order.
`Incidentally. a state of malfunction of the motor 12 can be
`indicated when either the self-diagnosis circuit 48a of the
`power circuit 48 or the self-diagnosis circuit 49a of the
`motor controller 49 issues an abnormal signal or when the
`power circuit 48 or the motor controller 49 is out of order.
`As has been mentioned above, in the first embodiment
`according to the present invention. the degree of accelerator
`pedal operation 6 determines the timing for a change from
`the motor drive mode to the enginelmotor drive mode and
`the travelling speed v determines the timing for a change
`from either the motor drive mode or the engine/motor drive
`mode to the engine drive mode and these timings are altered
`in accordance with upon the motor temperature t. In other
`words. in this particular embodiment. when the motor tem-
`peratnre t is high. the running range for the motor drive
`mode is reduced while the running range (operational areas)
`for the engjnelmotor drive mode and the engine drive mode
`are expanded.
`Accordingly, in this particular embodiment. the electric
`power supplied to the motor 12 can be reduced if the motor
`temperature t is high to decrease the load on the stator coil
`12b. It should be understood that a shortage of torque
`generated by the motor 12 is made up by a corresponding
`torque from the internal combustion engine 11. thus pre-
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`The generation of heat is increased, so that the coating of 10
`the wire melts to thereby cause a short-circuit in the motor
`12. The excessive heat generation means an energy loss for
`the motor 12, that is the torque is decreased and the stator
`coil 12b could burn. As the motor 12 malfunctions due to
`such problems, the vehicle can no longer move in the motor
`drive mode.
`As will be understood with reference to the associated
`drawings. upon detection of a malfunction in the motor drive
`assembly. rrmning range for the engine drive mode is
`expanded toward a low speed area in the drive mode map.
`In order to so alter the running range, the CPU 58 collects
`the results of the degree of accelerator pedal operation 9
`detected by the accelerator sensor 43. the travelling speed v
`detected by a speed sensor 44 provided at the counter drive
`shaft 32, and the motor temperature t detected by a tem-
`perature sensor 45 fixed at the stator coil 12b. Alternatively,
`the motor temperatrne t can be measured at the vicinity of
`the magneto stator 12a in the driving unit case or by sensing
`temperature of a cooling oil utilized for the motor 12 instead
`of monitoring the stator coil 12b temperature.
`In the drawings. the reference numeral 47 indicates the
`battery. 48 is a power circuit for supplying electric power to
`the motor 12. 48a is a self-diagnosis circuit which is
`provided in the power circuit 48 and adapted to diagnose the
`same and which comprises several diagnostic circuits, 49 is
`a motor controller controlling the power circuit 48 respon-
`sive to signals from the CPU 58, and 49a is a self-diagnosis
`circuit which is provided in the motor controller 49 and
`adapted to diagnose the same and which comprises several
`diagnostic circuits. The reference numeral 50 indicates a
`clutch on-off solenoid for operating the clutch C responsive
`to signals from the CPU 58. 51 is an engine throttle actuator
`regulating throttle opening responsive to signals from the
`CPU 58, and 52 is an engine starter for starting the engine
`11 upon receiving a signal from the CPU 58.
`The details of the CPU are depicted in FIG. 2. The CPU
`58 includes a main unit 41 with an arithmetic logic unit
`(ALU). RAM and ROM, input interfaces 59 and output ports
`60. Incidentally, the ROM is adapted to store the necessary
`drive mode maps defining running ranges for the respective
`drive modes. The input interfaces 59 input. to the main unit
`41, data such as the travelling speed v detected by the speed
`sensor 44,
`the degree of accelerator pedal operation 6
`detected by the accelerator sensor 43, battery residual charge
`measured by a battery charge detector 55, hereinafter
`detailed in the secxmd embodiment. and a confirmation of
`the motor state by a motor fault detector 56.
`The output ports 60 are adapted to send control signals
`respectively to the motor controller 49, the clutch on-off
`solenoid 50, the engine throttle actuator 51 and the engine
`starter 52.
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`Referring now to FIG. 3. there is shown a block diagram
`for the motor fault detector 56 in the above-described first
`embodiment.
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`In the drawing, the reference numeral 12 indicates the
`motor. 48 is the power circuit and 48a is the self-diagnosis
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`venting excessive heating of the motor 12 and severe
`damage by heat to the stator coil 12b. At a preferred low
`temperature for the motor 12. the copper wire used in the
`motor does not have high electrical resistance, so that the
`working eificiency of the motor 12 is good for optimum
`travel distance on one battery charge.
`The drive mode map in the first embodiment will be
`explained in detail with reference to FIG. 4.
`When the stator coil 12b of the motor 12 or the motor
`
`temperatln'e is normal. the vehicle according to the present
`invention is controlled in the motor drive mode in which the
`travelling speed v is lower than the predetermined
`changeover traveling speed v1 and the degree of accelaator
`pedal operation 9 is also lower than the predetermined value
`61. When the travelling speed v is lower than the changeover
`traveling speed v1 and the degree of accelaator pedal
`operation 6 is higher than the value 61. the vehicle moves in
`the engine/motor drive mode. Only when the travelling
`speed v is higher than the speed v1. is the vehicle adapted
`to move in the engine drive mode. Incidentally. such a
`hysteresis regarding a mode shift among the three modes
`divided according to the traveling speed v and the degree of
`accelerator pedal operation 6 is learned and stored for latter
`traveling.
`But. once the motor temperature t becomes high. the
`degree of accelerator pedal operation 61 is changed to
`another degree On as a changeova degree of accelerator
`pedal operation (B1>Bn) and the changeover traveling speed
`v1 is also changed to a speed vn (v l<vn). as shown in FIG.
`4.
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`Accordingly. when the motor tempaature t is high. when
`the traveling speed v is lower than the changeover travelling
`speed vn and when the degree of accelerator pedal operation
`9 is lower than the predetermined changeover degree of
`accelerator pedal operation 6n. the vehicle moves in the
`motor drive mode. When the speed v is lower than the speed
`vn and the degree 6 is larger than the degree 9n, the vehicle
`moves in the engine/motor drive mode. Only when the speed
`v is higher than the changeover traveling speed vn. does the
`vehicle move in the engine drive mode.
`FIG. 5 is a graphical representation showing a relation-
`ship between the motor temperature and the changeover
`degree of accelerator pedal operation in the first embodi-
`ment. FIG. 6 is a graphical representation showing a relation
`between the motor tempaature and the changeover traveling
`speed in the same embodiment. It will be noted from the
`drawing that the higher the motor temperature tn. the lower
`both the changeover degree of accelaator pedal operation
`On and the changeover traveling speed vn are set. Such a
`setting is stored in the CPU 58. specifically in the ROM.
`More specifically. when the motor temperatme t1 reaches
`20 degrees. the changeover degree of accelerator pedal
`operation 01 is set at 80(%) as a preferred value to start and
`accelerate the vehicle and the changeover travelling speed
`v1 is set at 80 (lcmlh) so as to move comfortably on the road
`As the motor temperature t2 reaches 80 degrees,
`the
`changeover degree of accelerator pedal operation 62 is set at
`50(%) and the changeover traveling speed v2 is set at 70
`(km/h). If the motor temperature t3 exceeds 100 degrees.
`both the changeover degree of accelerator pedal operation
`63 and the changeover traveling speed v3 are set at 0 (zero).
`Incidentally. in the description of the following second
`embodiment. the same reference numerals will be used to
`designate the same or similar components as those in the first
`embodiment. so that the description will be simplified.
`In this particular embodiment. the CPU 58 is adapted to
`expand the running ranges for the engine drive mode to
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`comply with the detected battery residual charge. In order to
`provide such a function. a battery residual charge detector 55
`is located intermediate the battery 47 and the CPU 58 as
`shown in FIG. 1.
`Referring now to FIG. 7. it depicts a block diagram
`showing the overall system of the battery residual charge
`detector 55 used in the hybrid vehicle according to the
`present invention.
`the reference numeral 47 indicates a
`In the drawing.
`battery, 55 is the battery residual charge detector. 61 is a
`circuit for charging and discharging. 61a is a discharge
`circuit and 61b is a charge circuit. There are provided an
`arnmeter 62 and a voltmeter 63 between the battery 47 and
`the circuit for charging and discharging 61 to confirm input
`and output electric power. thus detecting the residual battery
`charge. Such detection is done in a control unit 64 compris-
`ing an in/out power operational arrangement 640. a residual
`charge operational arrangement 64b. a memory 64c and a
`retrogradation correction arrangement 64d.
`It should be understood that the residual battery charge
`can be detected by other measures by utilizing the graphical
`repr'esentations shown in FIGS. 8 and 9.
`FIG. 8 is a graphical representation of a relationship
`between discharge current and terminal voltage afta 5
`seconds for detection of the battery residual charge. FIG. 9
`is a graphical representation showing the relationship
`between discharge duration and relative density in discharg-
`ing.
`As can be seen from FIG. 8. as the battay residual charge
`is decreased. the terminal voltage of the battery 47 drops.
`The degree of discharge of the battery can be measured by
`detecting the terminal voltage after 5 seconds to thereby
`determine the actual residual battery charge.
`In FIG. 9. as the residual battery charge is decreased.
`specific gravity of the electrolyte used in the battay 47
`decreases. Therefore. the degree of discharge of the battery
`can be measured as a change of the specific gravity to
`thereby determine the present residual battery charge. It is
`also possible to utilize both measures shown in FIGS. 8 and
`9 to measure the battery residual charge.
`Once the actual battery residual charge is determined. the
`battery residual charge detector 55 outputs the correspond-
`ing signal to the CPU 58.
`The CPU 58 is adapted to receive signals representing the
`battay residual charge and a malfundion of the battery and
`then change the drive mode maps as explained in connection
`with the first embodiment so as to expand the running sphere
`range for the engine drive mode. The CPU 58 retains. in the
`ROM. the fiISt drive mode map as depicted in FIGS. 10-12.
`the second drive mode map and the third drive mode map.
`The CPU 58 can notify the driva of a malfunction of the
`motor by means of a warning lump. Generally. the expansion
`of the running range for the engine drive mode is conducted
`by the CPU 58 responsive to the detected travelling speed v
`and the degree of accelerator pedal operation 6 the engine
`stand‘ 52 is then automatically operated. The internal com-
`bustion engine may also be manually started by the driva-
`utilizing the starter 52. When such an alteration of the drive
`mode maps is completed. the motor fault detector 56 is reset
`by a signal from the CPU 58.
`FIG. 10 is the first drive mode map utilized when the
`motor drive assembly is in good order. In this mode. as the
`l:ravelling speed v is lower than the changeover traveling
`speeds vA1. vA2 and the degree of accelerator pedal opera-
`tion 6 is lower than the changeover values for accelerator
`pedal operation 6A1. 6A2. the vehicle moves in the motor
`drive mode. When the traveling speed v is lower than the
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`speeds vA1. vA2 and the degree of accelerator pedal opera-
`tion 0 is higher than the changeover values for accelerator
`pedal operation 0A1. 0A2, the vehicle moves in the engine]
`motor drive mode. And when the speed v is higha than vAl,
`vA2, the vehicle moves in the engine drive mode.
`The preliminary learned hysteresis regarding the traveling
`speed v and the degree of accelerator pedal operation 6 for
`changing the mode is used for setting the changeover
`traveling speeds vA1. vA2 and the changeova degree of
`accelerator pedal operation values 0A1, 0A2.
`More particularly, the changeova traveling speed vA1 is
`set at 80 (km/h) and the speed vA2 is set at 70 (km/h) for
`smooth driving. Furthermore,
`the changeover value for
`degree of accelerator pedal operation 0A1 is set at 80% and
`the degree 0A2 is set at 60% so as to begin to move the
`vehicle in the motor drive mode.
`As has been described above, the motor drive mode is
`used when the vehicle which moves slowly and does not
`have much load, the engine/motor drive mode i