United States Patent
`
`[19]
`
`[11]
`
`4,335,429
`
`[45]
`Jun. 15, 1982
`Kawakatsu
`
`[54] CONTROL APPARATUS FOR
`ENGINE/ELECTRIC HYBRID VEHICLE
`
`[75]
`
`Inventor:
`
`[73] Assignee:
`
`Shiro Kawakatsu, Suita, Japan
`
`Daihatsu Motor Co., Ltd., Ikeda,
`Japan
`
`.'
`
`[21] Appl. No: 129,718
`[22] Filed:
`Mar. 12, 1980
`
`Foreign Application Priority Data
`[30]
`Mar. 20, 1979 [JP]
`Japan ...............................'... 54-34977
`
`Int. Cl.3 ................................................ B60K 1/00
`[51]
`[52] US. Cl.
`................................. 364/424; 180/65 A;
`364/426
`
`............... 364/424, 426, 442;
`[58] Field of Search
`180/65 R, 65 A, 65 C; 123/2; 290/1 A
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`180/65 A
`1/1975 Joslin
`3,861,484
`180/65 A
`3,923,115 12/1975 Helling ......
`180/65 A
`4,021,677
`5/1977 Rosen ........
`180/65 A
`4,042,056
`8/1977 Horwinski .
`4,097,752
`6/1978 Wulf et al.
`........................ 180/65 A
`
`
`
`_
`
`
`4,148,192, 4/1979 Cummings ................ 180/65 A
`4,180,138 12/1979 Shea .................................. 180/65 A
`
`Primary Examiner—Errol A. Krass
`Attorney, Agent, or Firm—Darby & Darby
`
`[57]
`ABSTRACT
`A hybrid vehicle comprises an internal combustion
`engine, a relatively large motor/generator and a rela-
`tively small motor/generator, which are controlled by a
`microcomputer based on the required torque of the
`vehicle as a function of time. When the engine is permit-
`ted to run, it is always operated in that region which
`minimizes fuel consumption. If the torque of the engine
`is too low to drive the vehicle, the relatively large
`» motor is energized to make up for the deficiency. When
`the engine produces excess torque, the relatively large
`motor/generator absorbs the excess and is operated as a
`generator to generate electricity. Braking torque is usu-
`ally obtained by operating the relatively large motor/-
`generator as a generator. When braking torque is insuf-
`ficient,
`the relatively small motor/generator is also
`operated as a generator to make up for the deficiency.
`
`26 Claims, 27 Drawing Figures
`
`DEED ETI
`
`PkEssuR
`
`I:
`
`EMF
`
`NI
`
`9
`
`T,
`
`H
`
`ENGINE
`
`
`
`
`CLUTCH” c,
`comm
`
`
`
`
`
`
`’7
`
`2]
`
`EC‘H’CI (‘2 (:3
`
`I9
`
`THROTTLE
`CONTROL
`
`TP
`
`
`hlv
`
`
`INPUT
`
`
`AME) EC
`
`ENGINE
`ENABLING
`
`
`
`”LLINPUT
`
`7 MTLLTEHP
`
`GENERATOR
`
`
`SECOND
`
`MOTOR/
`
`
`
`FIRST
`
`MOTOR/
`GENERATOR
`
`
`
`
`CURRENT
`CONTROL
`
`N2
`
`ES EC(M)
`
`BVL
`BVH
`
`VOLT
`
`BA TTERY
`
`BT
`BW
`
`B DH—Icur
`
`Page 1 of 35
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`

`’
`
`U.S. Patent
`
`Jun. 15, 1982
`
`Sheet 1 of17
`
`4,335,429
`
`FIG I
`
`
`
`\ FULL
`~
`THROTTLE
`LINE
`
`
`
`TORQUE(lg-m)
`
`0 ‘I—v——’y———'—'——'————1—-'————'—1————'———1—
`
`I5
`
`6/0
`‘FULL ACCELERATION
`.IMAX. TORQUE
`
`20
`
`25 30 J5 £0 (5 50
`55_ 602
`REVOLUTIUN (x10 rpm)
`
`
`
`
`
`TORQUE(BRAKING)0TORQUE(DRIVING)
`
`7n?§r‘ t 1’0 Z
`
`I FULL BRAKING
`
`‘Tr
`
`Page 2 of 35
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`

`U.S. Patent
`
`Jun. 15, 1982
`
`Sheet 2 of 17
`
`4,335,429
`
`>83:
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`Page 3 of 35
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`
`
`
`
`

`

`NI NI
`INTERFACE
`
`N2 N2
`
`TI
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`TI
`
`77
`
`‘H
`
`DA TA
`TABLE
`
`39
`
`4/
`
`43
`
`45
`
`INTERFAC
`
`AP
`
`BF
`
`57
`
`59
`
`US. Patent
`
`Jun. 15, 1982
`
`Sheet 3 of 17
`
`4,335,429
`
`FIG. 4
`
`MGIC
`4 7
`
`MGZC
`4?
`
`EC
`
`5/
`
`M61
`OUTPUT
`PORT
`
`M62
`OUTPUT
`PORT
`
`EC
`OUTPUT
`PoRT
`
`53
`
`35
`
`37
`
`F6
`'—' INTERFACE
`55
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`RPM)
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`
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`OUTPUT
`pom
`
`ENO
`OUTPUT
`PORT
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`OUTPUT
`PORT
`
`CI c2 c3 ‘
`
`5N0
`
`E3
`
`FIG. 5
`
`67o
`
`ACCEIERATION
`
`CIRCUIT
`+4? ——
`
`67
`
`
`
`IT
`
`BRAKING
`CIRCUIT
`
`
`
`Page 4‘of 35
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`

`US. Patent
`
`Jun. 15, 1982
`
`Sheet 4 of 17
`
`4,335,429
`
`FIG. 6A
`
`A u T
`
`0
`
`7/
`
`MANUAL
`
`ENGINE
`INCAPABLE
`We
`
`ENGINE
`MODE
`
`MOTOR
`INCAPABLE
`71”.
`
`MOTOR
`MODE
`
`
`GENERATOR
`INCAPABLE
`7‘1
`
`
`FIG. 53
`
`,
`
`77
`
` F6 (0),
`
`T0 53
`
`Page 5 of 35
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`

`

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`
`Page 6 of 35
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`

`

`US. Patent
`
`Jun. 15, 1982
`
`Sheet 6 of 17
`
`4,335,429
`
`FIG.
`
`IOA
`
`FIG.
`
`IOB 72»
` TORQUE
`
`THROTTLE
`0P£NING DEGREE
`
`100% (N)
`
`Page 7 of 35
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`US. Patent
`
`Jun. 15, 1982
`
`Sheet 7 of 17
`
`4,335,429
`
` TORQUE
`
`
`DA TA ( T)
`
`NUMBER" OF
`REVOLUTION
`DATA (N)
`
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`

`U.S. Patent
`
`Jun. 15, 1982
`
`Sheet 8 of 17
`
`4,335,429
`
`FIG.
`
`73
`
`START /
`
`REA D DATA
`
`(N1. N2, T1, T2, AR
`BF)
`
`[0]
`
`Tr =F (N2, AP/ BF)
`
`[OZ
`
`Tmu 2 =F (N2)
`
`T3u2=r1~2)
`
`103
`
`Tea = F (N!)
`Te1= F (NI)
`
`’04
`
`105
`
`N0
`
`YES
`
`M+G
`
`OTORING
`FLAG
`SET?
`
`’55 107
`
`GENERATING
`FLAG
`SET?
`
`No
`
`Page 9 of 35
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`106
`
`”0
`
`
`
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`

`US. Patent
`
`Jun. 15, 1982
`
`Sheet 9 of 17
`
`4,335,429
`
`N0
`
`716
`
`Page 10 of 35
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`

`US. Patent
`
`Jun. 15, 1982
`
`Sheet 10 of 17
`
`4,335,429
`
`FIG.
`
`I534
`
`
`
`RESET
`
` YES
`
`TIMER
`
`
`
`
`Page 11 of 35
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`US Patent
`
`Jun. 15, 1982
`
`Sheet 11 of 17
`
`4,335,429
`
`FIG.
`
`I56
`
`N0
`
`219
`
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`US. Patent
`
`Jun. 15, 1982
`
`Sheet 12 of 17
`
`4,335,429
`
`FIG.
`
`I5D
`
`226
`
`ENG/NE
`
`ENABLE
`
`
`
`
`
`
`
`
`
`
`
`
`
`233
`
`‘ 2.34
`
`ENGINE
`DISABLE
`
`
`
`
`OUTPUT
`
`"ENO"
`
`Page 13 of 35
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`
`
`230
`
`SET TIMER (t3)
`
`YES
`
`Page 13 of 35
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`

`. US. Patent
`
`Jun. 15, 1982
`
`Sheet 13 of 17
`
`4,335,429
`
`
`
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`US. Patent
`
`Jun. 15, 1982
`
`Sheet 14 of 17
`
`4,335,429
`
`FIG. 78
`
`
`
`FIG.
`
`19
`
`ErM
`
`,5,
`
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`US. Patent
`
`Jun. 15, 1982
`
`Sheet 15 of 17
`
`4,335,429
`
`
`CONTROL
`
`ClUTCH
`
`[(01) CI £2 63
`
`Page 16 of 35
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`US. Patent
`
`Jun. 15, 1982
`
`Sheet 16 of 17
`
`4,335,429
`
`FIG.
`
`v
`
`
`
`
`21
`
`
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`312
`
`Page 17 of 35
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`US. Patent
`
`Jun. 15, 1982
`
`Sheet 17 of 17
`
`4,335,429
`
`FIG. 22
`
`
`
`
`
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`1
`
`4,335,429
`
`CONTROL APPARATUS FOR ENGINE/ELECTRIC
`HYBRID VEHICLE
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`The present invention relates to an apparatus for
`controlling a hybrid vehicle. More specifically,
`the.
`present invention relates to an apparatus for controlling
`a hybrid vehicle to reduce its fuel consumption.
`2. Description of the Prior Art
`An electric vehicle is one of the most effective means
`of transportation by virtue of its freedom from‘pollution
`as compared with vehicles employing other‘ conven-
`tional prime movers. However, an electric vehicle suf-.
`fers from various disadvantages; a long period is re-
`quired to charge the battery, and both running distance
`and running time are short. In view of the foregoing, a
`hybrid vehicle (an electric vehicle with an internal con-
`bustion engine) has been proposed and put into practical
`use, eliminating these disadvantages without losing the
`advantages of an electric vehicle. Naturally such a hy-
`brid vehicle consumes fuel in an engine running mode
`and consumes electric power. in a motor running mode.
`An automobile having the smallest possible fuel con-
`sumption has been desiredplt has also been desired to
`purify exhaust gas frOm the automobile since gas from
`an engine is one cause of air pollution. It has been well‘
`known that exhaust gas from an engine is purer when
`engine efficiency15 better.
`On the other hand, an automotive internal combus«
`tion engine requires a wide range of torque and speed so
`as to be adaptable to conditions of use, such as constant
`speed operation, acceleration, hill climbing and the like.
`Nevertheless, each internal combustion engine has a
`region‘in which its fuel consumption is minimized. An
`automotive internal combustion engine operates in that
`region when climbing hills or accelerating. Therefore, it
`is conceivable :to minimizeengine capacity and there-
`fore minimize maximum power, so that the automobile
`is normally operated in its region of minimum fuel con-
`sumption. However, with only such ' an engine, it is
`impossible to attain a required driving torque which
`will suffice in .all running conditions. Therefore,
`the
`inventors of the present invention previously proposed
`an improved hybrid vehicle wherein the engine is al-
`ways operatedin its most fuel-efficient region, and driv-
`ing torque deficiencies are made up by an electric mo-
`tor, whereby overall fuelconsumption as well as overall
`energy efficiency of the vehicle is enhanced.
`However, previous hybrid vehicles required an elec-
`tric motor having a power sufficient to satisfy all speed
`characteristics and torque requirements for all running
`conditions. In such cases, motor‘and engine efficiency is
`poor in a low load condition such as normal operation,
`and saving energy is difficult. On, the other hand,_it is
`well-known that an electric motorrcan be used as a
`generator during braking,
`thus saving energy. How~
`ever, since the motor in a previously proposed hybrid
`vehicle has a large continuous rating, it is impossible to
`so use the motor. More specifically, when a motor with
`a large continuous rating is used in a hybrid. vehicle, the
`motor does not work well as a generator, because when
`the vehicle speed drops, thelmotor will not produce a
`sufficiently high voltage It is also conceivable to em-
`ploy a voltage boosting means such as a transformer,
`but even this cannot provide a sufficiently high voltage
`without having extremely poor efficiency. Since a vehi-
`
`5
`
`10
`
`'
`
`15'
`
`20
`
`‘25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`6O
`
`65
`
`the present
`- In‘order to eliminate these problems,
`invention employs an internal combustion engine and
`two electric mOtors in a hybrid vehicle. The internal
`combustion engine is only allowed to operate in its
`region of maximum fuel efficiency. When the vehicle
`output shaft speed is within an optimum speed range of
`the internal combustion engine, any additional torque
`required will be supplied by one motor while the engine
`operates at its maximum torque rating. If output shaft
`speed is outside this optimum speed range, additional
`torque is usually supplied by one of the electric motors.
`If torque is still deficient, the deficiency is supplied by
`the other motor.
`According to the present invention, the internal com-
`bustion engine is only operated in its region of minimum
`' fuel consumption and efficiency is drastically improved.
`When the engine produces insufficient torque by itself,
`the additional torque is supplied by the electric motors.
`Hence, torque sufficient for all running conditions (such
`as constant speed operation, acceleration, or hill climb-
`ing) can be attained. Since two electric motors are used
`in the vehicle, they can provide enough torque to run
`the vehicle even if the engine is not permitted to oper-
`ate.
`
`2
`cle is operated at speeds between 0 km/h to 100 km/h,
`it could very often happen that the speed would not be
`high enough to. provide enough voltage to regenerate
`its battery. Accordingly, a hybrid vehicle is not efficient
`enough. The” - size and cost of a motor/generator in-
`crease approximately as the square of its capacity, and a
`motor/generator that is capable of coping with all run-
`ning conditions becomes large and extremely expensive.
`
`. SUMMARY OETHE INVENTION
`
`In a preferred embodiment of the present invention,
`one of these two electric motors is coupled to the output
`shaft of the vehicle. That motor is constantly used for
`supplying torque, while the other motor is used as an
`auxiliary motor for supplying a deficient torque. Ac-
`cordingly, the one motor need not be large and the
`auxiliary motor may have a short time rating, such as
`three minutes. Accordingly, the total cost and size of
`these tWO electric motors can be reduced. If the torque
`required is less than the minimum torque produced by
`the engine in its best fuel consumption range, the inter-
`nal combustion engine is operated at
`this minimum
`torque, while the excess torque is absorbed by operating
`the one motor as a generator The two motors can be
`more efficient even at relatively slow vehicle speed, and
`more energy is saved. More specifically, even when the
`torque required is less than the minimum torque pro-
`duced when the engine is permitted to operate, degra
`dation of fuel comsumption or thermal efficiency is
`avoided by operating the engine at
`that minimum
`torque, while the excess torque is absorbed by the gen-
`erator. Driving torque and required torque are thus
`matched. Electricity generated by the generator regen-
`erates the battery without being wasted and loss of
`electrical outputis decreased. Overall energy savings
`result.
`’
`
`Accordingly, a principal object of the present inven—
`tion is to provide an improved hybrid vehicle.
`Another object of the present invention is to provide
`an improved, hybrid vehicle having an internal combus-
`tion engine and two electric motors or motor/genera—
`tors.
`
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`4,335,429
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`3
`A further object of the present invention is to provide
`an apparatus for controlling a hybrid vehicle that can
`minimize fuel consumption of its internal combustion
`engine.
`'
`Still a further object of the present invention is to
`provide an apparatus for controlling a hybrid vehicle
`that can achieve the best overall energy efficiency.
`Still another object of the present invention is to
`provide an apparatus for controlling a hybrid vehicle
`which will save energy in all operating conditions.
`These objects and other objects, features, aspects and
`advantages of the present invention will become more
`apparent from the following detailed description of the
`present invention when taken- in conjunction with the
`accompanying drawings.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a graph showing the fuel consumption char-
`acteristics of a gasoline engine, wherein the abscissa
`indicates output shaft speed (X 100 rpm) and the ordi-
`nate indicates the shaft torque (kg-m);
`FIG. 2 is a graph showing the operating regions used
`in the present invention, wherein the abscissa indicates
`output shaft speed and the ordinate indicates the re-
`quired shaft torque;
`FIGS. 3, 4, 5, 6A, 6B and 7 are block diagrams depict-
`ing one embodiment of the present invention;
`FIG. 8 is a graph showing the relation of a variable
`with respect to shaft speed and the torque Tml, Tgl of
`a first motor/generator, wherein the abscissa indicates
`the speed and the ordinate indicates the torque;
`FIG. 9 is a graph showing the relation of a variable
`with respect to shaft speed and the torque Tm2, Tg2 of
`a second motor/generator, wherein the abscissa indi-
`cates the speed and the ordinate indicates the torque;
`FIG. 10A is a graph showing the relation of the de-
`gree of throttle opening with respect to shaft speed and
`torque Te of the internal combusion engine;
`FIG. 10B is an enlarged portion of the FIG. 10A
`graph;
`FIG. 11 is a' view showing an outline of a preferred
`embodiment of a means for detecting the torque and the
`shaft speed;
`FIG. 12 is a graph showing an example of waveforms
`for explaining operation of the FIG. 11 device for de-
`tecting torque;
`»
`.
`FIGS. 13 to 19 are flow diagrams for explaining an
`operation of the present invention;
`,
`FIG. 20 is a schematic diagram of an actuator and a
`control system where a synchro type clutch is used as a
`transmission or clutch mechanism;
`FIG. 21 is a sectional view showing in detail a syn-
`chro type clutch; and
`FIG. 22 is a perspective view for explaining shift
`forks.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`FIG. 1 is a graph showing fuel consumption charac-
`teristics of a given internal combustion engine (referred
`to as an engine hereinafter) for depicting the principle
`of the present invention, wherein the abscissa indicates
`the number of revolutions of the shaft of the engine
`(X 102 rpm) and the ordinate indicates the shaft torque
`(kgm). Such a graph showing a fuel consumption char—
`acteristic is well-known as a map of specific fuel con-
`. sumption. In particular, FIG. 1 applies to a gasoline
`engine of 1000 cc having four cylinders. More specifi-
`
`4
`cally, by taking an example in the FIG. 1 graph, the fuel
`consumption is minimal, or the thermal efficiency is
`maximal, when the gasoline engine is run within a range
`in which the specific fuel consumption (gr/PSh) is
`“210”. The present
`invention operates such that an
`engine in a hybrid vehicle is run within a region having '
`a relatively better thermal efficiency based on the spe-
`cific fuel consumption as shown in FIG. 1, for example,
`only the engine is run as a prime mover of the vehicle if
`the shaft speed and the torque reside in that range of the
`specific fuel consumption which is less than approxi-
`mately 220 to 230 (gr/PS-h). The inventive hybrid vehi-
`cle employs two motors. If the shaft speed of the vehi-
`cle is outside the speed range in which the engine is
`permitted to operate, one and the other motors are
`selectively energized in a proper combination to attain
`the required torque and, when the required torque of
`the vehicle exceeds a predetermined upper limit of the
`torque range in which the engine is permitted to oper—
`ate, a combination of the engine and one motor is used
`as a prime mover.
`FIG. 2 is another graph for depicting the principle of
`the present invention, wherein the abscissa indicate the
`speed of the output shaft of a vehicle and the ordinate
`indicates the shaft torque. Referring to FIG. 2, the prin-
`ciple of the present invention will be described in detail.
`More specifically, referring to FIG. 2, within the range
`of the region
`(which is an approximate portion of a
`region of specific fuel consumption (gr/PSh) which is
`less than “210 to 230”, for example) only the engine is
`run as a prime mover. The region Q) is defined by an
`upper limit line of a curve representing a throttle open—
`ing degree characteristic running through a portion of
`the region of the specific fuel consumption being less
`than 210 to 230 (gr/PS-h), i.e., a line in which the throt-
`tle opening is 100%, and a line in which the throttle
`opening is 50%, and also defined by an upper limit value
`Neu and a lower limit value Nel of the optimum range
`of the engine in which the engine will operate with such
`specific fuel consumption. Only the engine is operated,
`if the required torque Tr falls within the above de-
`scribed region @. Region (4) includes a region where
`fuel consumption is worse than 220 to 230 (gr/PS-h) and
`furthermore it could happen that some portion is within
`the range of the fuel consumption bein less than 220 to
`230 (gr/PS-h) but outside the region
`. The reason is
`that the curve of the fuel consumption does not neces-
`sarily coincide with the characteristic curve represent-
`ing throttle opening and a region of a better thermal
`efficiency was selected in an approximate manner in
`determining the region @. Meanwhile, it is pointed out
`that FIG. 2 and FIGS. 8, 9, 10A and 10B to be described
`subsequently have been illustrated in a simplified man—
`ner as compared with FIG. 1 and accordingly these
`illustrations are not precise in a strict sense, inasmuch as
`these are referred to only for describing the principle of
`the present invention.
`According to this embodiment, at least one of the two
`motor/generators used in the hybrid vehicle is run as a
`motor to provide a prime mover of the vehicle within
`the regions 6) and (D of FIG. 1. Since the region (D
`is a region where the required torque Tr exceeds the
`upper limit value of the torque which can be supplied
`by the above described one motor, the other motor is
`run to supply the torque deficiency within the above
`described region
`. Meanwhile, since the region © is
`within the. torque range where the required torque is
`attained by the above described one motor, only the
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`5.
`above described one motor is used as a prime mover of
`the vehicle.
`.
`
`The region @ is a region where the required torque
`Tr exceeds an upper limit value of the torque range in
`which the engine can be run considering its fuel con-
`sumption characteristic but where the shaft speed of the
`vehicle is within the range of shaft speeds in which the
`engine can run. In such a case, the engine is controlled
`to operate at the upper limit torque of the above de—
`scribed allowed torque range and torque deficiency is
`supplied by on of the two motors. Although both of
`the regions 63 and
`are included within the
`re ion @, this control occurs such that in the region
`the other motor is operated as a starter motor to
`start the engine when the engine is stopped.
`The region @ is a range wherein the output shaft
`speed of the vehicle is within the optimum shaft speed
`range in which the engine can run and wherein the
`required torque Tr falls between the lower limit of the
`torque range in which the engine can operate, and zero.
`In the region @ the engine is operated at the lower
`~ limit of the above described allowed torque range as a
`prime mover of the vehicle and,
`in order to absorb
`excessive torque, the 'one motor/generator out of the
`above described two motor/generators is operated as a
`generator.
`The regions @ and ® in the FIG. 2 graph shows
`regions where the required torque is negative (—Tr). In
`the region 6) one. motor out of the above described
`two motors is operated as a generator, thereby to attain
`a braking torque. However, in the region CD the vehi-
`cle has insufficient braking torque when only the above
`described motor/generator is operated as a generator,
`and in this case the other motor is also operated as a
`generator to supply the braking torque deficiency.
`Meanwhile, when these two motor/generators are op-
`erated as generators, it may be considered that a major
`portion of the generated electric output is regenerated
`to a battery. Accordingly, by uniquely controlling the
`vehicle depending on the respective regions shown in
`the FIG. 2 graph, an improved engine/electric hybrid
`vehicle is provided wherein the fuel consumption of the
`engine is minimized and the loss of energy by the two
`motor/generators is also minimized.
`FIGS. 3 to 7 are block diagrams showing one em-
`bodiment of the present invention. An engine/electric
`hybrid vehicle of the embodiment shown comprises one
`engine 1 and first and second motor/generators 5 and 7.
`The engine 1 and two motor/generators 5 and 7 are
`controlled by a microprocessor or microcomputer 35.
`The engine 1 may comprise a gasoline engine having
`a specific fuel comsumption characteristic as shown in
`FIG. 1, for example. The output shaft of the engine 1 is
`detachably coupled through a transmission or a clutch
`mechanism 3 serving as a coupling means to the first
`motor/generator 5 or the second motor/generator 7.
`The clutch mechanism 3 comprises three clutches C1,
`C2 and C3. In the embodiment shown, these clutches
`C1, C2 and C3 each are implemented by means of an
`electromagnetic clutch, which is responsive to a signal
`from a clutch control circuit 21 (to be described subse—
`quently) to selectively disconnect or connect them. The
`second motor/generator 7 is a motor having a large
`continuous rating, whereas the first motor/generator 5
`is a relatively small sized motor having a relatively
`short time rating of, e. g., about three minutes. The out—
`put shaft of the second motor/generator 7 is coupled
`through a transmission means such as a differential gear
`
`6
`(not shown) to the wheel shaft and thus to wheels (not
`shown). Thus, a power train of the engine/electric hy-
`brid vehicle of the embodiment shown is established.
`A speed sensor 9 and a torque sensor 11 are opera—
`tively coupled to the output shaft of the engine 1. Simi-
`larly, a speed sensor 13 and a torque sensor 15 are opera-
`tively coupled to the output shaft of the second motor/-
`generator 7 and thus of the output shaft of the vehicle.
`These speed sensors 9 and 10 and the torque sensors 11
`and 15 may be implemented as any one of various well-
`known structures. In the embodiment shown, such a
`structure as shown in FIG. 11 is employed and will be
`described in detail below. As described previously, the
`engine 1 may comprise a gasoline engine, for example,
`to which a throttle control 17 and an engine enabling
`means 19 are coupled. The throttle control 17 comprises
`a butterfly valve, for example, for controlling the de-
`gree of opening of a carburetor (not shown) and a ser-
`vomotor or a pulse motor for driving the butterfly
`valve. The engine enabling means 19 comprises means
`for connecting a fuel line, an ignition circuit and the
`like. The engine 1 may be provided with a starter motor
`serving as a starting means. Where the engine 1 is a
`diesel engine, the throttle control 17 comprises a butter-
`fly valve (not shown) for adjusting the amount of air
`, being fed into engine cylinders, a control device such as
`a servomotor (not shown) for an injector pump (not
`shown) for pressure feeding fuel into cylinders after
`adjustment of a fuel injection amount, and the like.
`Likewise, where the engine 1 is a diesel engine, the
`engine enabling means 19 comprises a means for con-
`necting a fuel line, a means for enabling an injection
`pump and the like. Although not shown, the engine 1 is
`further provided with an engine temperature sensor for
`measuring the temperature of the engine, an oil pressure
`sensor for measuring the oil pressure of an engine lubri-
`cating oil, and the like. Since these temperature and oil
`pressure sensors are well-known to those skilled in the
`art, detailed description thereof will be omitted.
`The engine temperature sensor is adapted to measure
`the temperature of water for cooling the engine, for
`example, such that if the temperature reaches 110° C.,
`for example, the output ET is obtained, indicating that
`the engine is overheated. The oil sensor is adapted to
`measure the pressure of the engine oil for lubrication,
`such that a signal E0 is obtained when the pressure
`becomes smaller than 2 kg/cmz. These signals ET and
`E0 are applied to flag lamp drivers to be described
`subsequently.
`The first motor/generator 5 and the second motor/-
`generator 7 are each driven as a motor by electric
`power from a battery 23 and are each operated as a
`generator to regenerate the battery 23. The first mo—
`tor/generator 5 may comprise a direct current series
`motor/generator. Accordingly, a motor current control
`27 is interposed between the first motor/generator 5
`and the battery 23 for the purpose of controlling the
`motor current. The motor current control 27 responds
`to a signal MG1C (to be described subsequently) to
`control current flowing through the first motor/genera-
`tor 5 based on a voltage fed back from a shunt resistor
`25. The second motor/generator 7 may comprise a
`direct current shunt motor/generator,
`for example.
`Accordingly, an armature current control 31 for con—
`trolling armature current in an armature (not shown)
`included in the second motor/generator 7, and a field
`current control 35 for controlling field coil current in a
`field coil (not shown) included in the second motor/-
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`7
`generator 7 are interposed between the second motor/-
`generator 7 and the battery 23. The armature current
`control 31 responds to signals MG2C, BF(M) and
`AP(M) (to be described subsequently) to control the
`armature current Ia of the second motor/generator 7
`based on a voltage fed back from a shunt resistor 29
`interposed in the current path. The field current control
`35 responds to the speed data N2 obtained from the
`speed sensor 13 coupled to the output shaft to control
`current flowing through the field coil based on a volt-
`age fed back from a shunt resistor 33 interposed in the
`current path.
`The field current of the second motor/generator 7 is
`controlled in response to the shaft speed N2 as de-
`scribed in the following. More specifically,
`the field
`current control 35 is structured such that a strengthened
`field current is applied where the speed N2 is smaller
`than a predetermined value such as 3000 rpm, a weak-
`ened field current is applied where the speed N2 ex-
`ceeds a predetermined value such as 6000 rpm, and a
`field current in reverse proportion to the speed N2 is
`applied when the speed N2 falls between the above
`described predetermined values of 3000 rpm and 6000
`rpm.
`'
`The second motor/generator 7 has a larger continu-
`ous rating than the first motor/generator 5 and accord-
`ingly the second motor/generator 7 is used as a princi-
`pal motor/generator, whereas the first motor/generator
`5 is used as an auxiliary motor/generator. Accordingly,
`although not shown, the second motor/generator 7 is
`provided with a temperature sensor, so that if the tem-
`perature of the second motor/generator exceeds a pre-
`determined value such as 120° C. a signal MT is ob-
`tained,
`indicating that the second motor/generator 7
`has been overheated. It would be, apparent
`that
`the
`temperature for providing the signal MT may be differ-
`ent depending on the insulation materials used in the
`motor/generator 7.
`Although not shown, the battery 23 may comprise a
`voltage sensor for measuring a voltage level of the
`battery 23, a battery temperature sensor for measuring a
`temperature of the battery 23, a level sensor for measur—
`ing an electrolyte level of the battery 23, and the like.
`These sensors are implemented in a well-known man-
`ner. For example, when the voltage of the battery be-
`comes lower than 1.6 V per unit cell, a signal BVL is
`provided, indicating an overdischarged state, and con—
`versely, if the voltage of the battery exceeds 2.5 V per
`unit cell, a signal BVH is provided, indicating an over-
`charged state. The temperature sensor measures the
`temperature of an electrolyte stored in the battery case
`(not shown) of the battery 23 or the temperature of the
`side surface of the battery case, so that when the tem-
`perature exceeds 60° C., for example, a signal ET is
`provided. Generation of the signal BT means that the
`battery 23 has been overheated and electricity cannot be
`charged anymore in the battery 23. On the other hand,
`the electrolyte level sensor may comprise a float sensor,
`for example, which is adapted such that a signal BW is
`provided when the electrolyte stored in the battery case
`drops below the uppermost ends of the electrode plates
`disposed in the battery case. The electrolyte level for
`providing the signal BW may be set such that the signal
`BW is provided when the electrolyte surface is reduced
`to slightly above the uppermost end of the electrode
`plates; however, alternatively the signal BW may be
`provided even when the electrolyte level comes below
`the uppermost ends of the electrode plates.
`
`8
`The clutch control 21 is structured such that when
`
`‘
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`signals cl, 02 and c3 (to be described subsequently) are
`provided, the correspondingclutches C1, C2 and C3
`are coupled. The clutch control 21 is also responsive to
`the signal EC(M) to control the clutch C1 included in
`the clutch mechanism 3.
`-
`The above described throttle control 17 is responsive
`to a signal EC or AP(E) (to be described subsequently)
`to control a servomotor for controlling the degree of
`carburetor opening. The engine enabling means 19 is
`responsive to a signal ES or EC(M) (to be described
`subsequently) to connect a fuel
`line or to enable an
`ignition circuit, as described previously.
`Now referring to FIGS. 11 and 12, the speed sensors
`9 and 13 and the torque sensors 11 and 15 will be de-
`scribed. The FIG. 11 embodiment implements both a
`speed sensor and a torque sensor. The speed torque
`sensing mechanism comprises shafts SH] and SH2 and a
`torsion bar TB coupling these shafts SH] and SH2.
`Metallic toothed wheels G1 and G2 are fixed to both
`ends of the torsion bar TB for integral rotation there-
`with. The shaft SHl is coupled to the output shaft of the
`engine 1 or the second motor/generator 7, whereas the
`shaft SH2 is coupled to the clutch mechanism 3 or a
`differential gear (not shown). Magnetic sensors MS]
`and M82 including magnetic resistance elements are
`provided in the vicinity of the respective peripheral
`surfaces of the above described metallic toothed wheels
`G1 and G2. The sensors M81 and M82 provides alter-
`nating current signals having the waveforms shown in
`FIG. 12 as the respective