`
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`HYBRID VEHICLE”
`ALEX J. BEVERINBKY
`
`Inventor:
`
`W T
`
`his application claims priority from Provisional Application
`Serial Number
`60/100,095, filed September 14, 1998.
`
`5 mm
`
`This application relates to improvements in hybrid vehicles,
`
`that is, vehicles in which both an internal combustion engine and
`
`one or more electric motors are provided to supply torque to the
`
`1%
`ifi
`E
`2;
`:3
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`driving wheels of the vehicle. More particularly, this invention
`relates to a hybrid electric vehicle that is fully competitive with
`presently conventional vehicles as regards performance, operating
`convenience, and cost, while achieving substantially improved fuel
`economy and reduced pollutant emissions.
`
`£3 W
`:3
`For many years great attention has been given to the problem
`a5
`of reduction of fuel consumption of automobiles and other highway
`?3
`vehicles. Concomitantly very substantial attention has been paid
`‘3
`to reduction of pollutants emitted by automobiles
`and other
`20
`vehicles. To a degree, efforts to solve these problems conflict
`
`with one another. For example,
`
`increased thermodynamic efficiency
`
`and thus reduced fuel consumption can be realized if an engine is
`operated at higher temperatures. Thus there has been substantial
`interest in engines built of ceramic materials withstanding higher
`combustion temperatures than those now in use. However, higher
`combustion temperatures in gasoline-fueled engines lead to increase
`
`25
`
`in certain undesirable pollutants, typically Nox.
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`Another possibility for reducing emissions is to burn mixtures
`
`of gasoline and ethanol ("gasohol"), or straight ethanol. However,
`to date ethanol has not become economically competitive with
`
`to any great
`gasoline, and consumers have not accepted ethanol
`degree. Moreover,
`to make an alternate fuel such as ethanol
`
`appreciable
`to achieve
`necessary
`extent
`to the
`available
`improvements in nationwide air quality and fuel conservation would
`
`10
`
`require immense costs for infrastructure improvements; not only the
`entire nation's motor fuel production and delivery system, but-also'
`
`the vehicle manufacture, distribution, and repair system, would
`
`have to be extensively revised or substantially duplicated.
`
`One proposal for reducing pollution in cities is to limit the
`
`use of vehicles powered by internal combustion engines and instead
`
`employ electric vehicles powered by rechargeable batteries. To
`
`date, all such "straight electric" cars have had very limited
`
`range,
`
`typically no more than 150 miles, have insufficient power
`
`for acceleration and hill climbing except when the batteries are
`
`substantially fully charged,
`
`and require substantial
`
`time for
`
`battery recharging. Thus, while there are many bircumstances in
`
`which the limited range and extended recharging time of
`
`the
`
`batteries would not be an inconvenience, such cars are not suitable
`
`for all the travel requirements of most individuals. Accordingly,
`an electric car would haVe to be an additional vehicle for most
`
`users, posing a substantial economic deterrent. Moreover, it will
`be appreciated that
`in the United States most electricity is
`generated in coal-fired power plants,
`so that using electric
`vehicles merely moves the source of the pollution, but does not
`eliminate it. Furthermore, comparing the respective net costs per
`
`mile of driving, electric vehicles are not competitive with
`ethanol-fueled vehicles, much less with conventional gasoline-
`fueled vehicles. See, generally, simanaitis, "Electric Vehicles",
`
`126—136; Reynolds,
`Road a Track, May 1992, pp.
`CRX", Road & Track, October 1992, pp. 126-129.
`
`"AC Propulsion
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`Brooks et al U.S. patent 5,492,192 shows such an electric
`
`vehicle;
`
`the invention appears to be directed to incorporation of
`
`traction control
`antilock braking and
`otherwise conventional electric vehicle.
`
`technologies
`
`into an
`
`10
`
`Much attention has also been paid over
`
`the years
`
`to
`
`development of electric vehicles including internal combustion
`
`engines powering generators,
`
`thus eliminating the defect of limited.
`
`range exhibited by simple electric vehicles. The simplest such
`
`vehicles operate on the same general principle as diesel—electric
`locomotives used by most railroads.
`In such systems, an internal
`
`combustion engine drives a generator providing electric power to
`traction motors connected directly to the wheels of the vehicle.
`
`This
`
`system has
`
`the advantage that
`
`no variable gear
`
`ratio
`
`transmission is required between the diesel engine and the wheels
`of the locomotive.
`
`More particularly, an internal combustion engine produces zero
`
`and reaches\its torque peak
`torque at zero engine speed (RPM)
`somewhere in the middle of its operating range. Accordingly, all
`
`£12 '
`
`vehicles driven directly by an internal combustion engine (other
`than certain single-speed vehicles using friction or centrifugal
`clutches, and not useful for normal driving) require a variable-
`
`ratio transmission between the engine and the wheels, so that the
`engineis torque can be matched to the road speeds and loads
`encountered. Further, some sort of clutch must be provided so that
`
`the engine can be mechanically decoupled from the wheels, allowing
`the vehicle to stop while the engine is still running, and to allow
`some slippage of the engine with respect to the drive train while
`starting from a stop.
`It would not be practical
`to provide a
`diesel locomotive with a multiple speed transmission, or a clutch.
`Accordingly,'
`the additional
`complexity of
`the generator
`and
`electric traction motors is accepted. Electric traction motors
`produce full'torque at zero RPM and thus can be connected directly
`to the wheels; when it is desired that the train should accelerate,
`3
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`1s
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`the diesel engine is simply throttled to increase the generator
`output and the train begins to move.
`
`U!
`
`The same drive system may be employed in a smaller vehicle
`such as
`an
`automobile or
`truck,
`but has
`several distinct
`
`In particular, and as discussed
`disadvantages in this application.
`in detail below in connection with Figs. 1 and 2, it is well known
`
`10
`
`E5
`,3.
`
`30
`
`35
`
`internal combustion engine is most
`_that- a gasoline or other
`near
`its maximum output
`torque.
`efficient when
`producing
`Typically,
`the number of diesel locomotives on a train is selected
`
`in accordance with the total tonnage to be moved and the grades to
`
`be overcome, so that all the locomotives can be operated at nearly
`full torque production. Moreover, such locomotives tend to be run
`
`at steady speeds for long periods of time. Reasonably efficient
`fuel use is thus achieved. However, such a direct drive vehicle
`would not achieve good fuel efficiency in typical automotive use,
`involving many short trips,
`frequent stops in traffic, extended
`low-speed operation and the like.
`
`So-called "series hybrid" electric vehicles have been proposed
`
`for automotive use, wherein batteries are used as energy storage
`devices, so that an internal combustion engine provided to power a
`
`generator can be operated in its most fuel-efficient output power
`
`range while still allowing the electric traction motor(s) powering
`
`the vehicle to be operated as required. Thus the engine may be
`loaded by supplying torque to a generator charging the batteries
`while supplying electrical power
`to the traction motor(s)
`as
`required, so as to_operate efficiently. This system overcomes the
`
`limitations of electric vehicles noted above with respect
`
`to
`
`Thus, as compared to a
`limited range and long recharge times.
`conventional vehicle, wherein the internal
`combustion engine
`
`in a series hybrid electric
`delivers torque directly to the wheels,
`vehicle,
`torque is delivered from the engine to the wheels via a
`
`serially connected generator used as
`
`a battery charger,
`
`the
`
`battery,
`
`and the traction motor. Energy transfer between those
`4
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`components consumes at least approximately 25% of engine power.
`Further, such components add substantially to the cost and weight
`of
`the vehicle;
`in particular,
`an electric motor capable of
`providing sufficient torque to meet all expected demand, e.g.,
`to
`allow reasonable performance under acceleration, during hill-
`climbing and the like, is rather heavy and expensive. Thus, series
`hybrid vehicles have not been immediately successful.
`
`10
`
`'A more promising "parallel hybrid" approach is shown in U.S.
`Patent Nos. 3,566,717 and 3,732,751 to Berman et al. In Berman et
`a1 an internal combustion engine and an electric motor are matched
`through a complex gear
`train so that both can provide torque
`directly to the wheels.
`
`the internal combustion engine is run in
`In Berman et al,
`several_ different modes. Where
`the output of
`the
`internal
`combustion engine is more than necessary to drive the vehicle
`("first mode operation")
`the engine is run at constant speed and
`excess power is converted by a first motor/generator ("Speeder")
`to
`electrical energy for storage in a battery.
`In "second mode
`operation",
`the internal combustion engine drives
`the wheels
`directly, and is throttled. When more power is needed than the
`engine can provide, a second motor/generator or "torquer" provides
`additional torque as needed.
`
`Berman et a1 thus show two separate electric motor/generators
`separately powered by the internal combustion engine; the "Speeder"
`charges the batteries, while the "torquer" propels the vehicle
`forward in traffic. This arrangement
`is a source of additional
`complexity, cost and difficulty, as two separate modes of engine
`control are required. Moreover,
`the operator must control
`the
`transition between the several modes of operation.
`Such a complex
`vehicle is unsuited for
`the automotive market.
`Automobiles
`intended for mass production can be no more complicated to operate
`than conventional vehicles, and must be essentially "foolproof",
`5
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`30
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`C.
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`that
`
`is,
`
`resistant to damage that might be caused by operator
`
`error. Further,
`
`the gear train shown by Berman et al appears to be
`
`quite complex and difficult to manufacture economically. Berman et
`al also indicate that one or even two variable-speed transmissions
`
`lines 19 - 22 and 36 - 38 of
`may be required; see, e.g., col. 3,
`patent 3,566,717, and col. 2,
`lines 53 - 55 of patent 3,732,751.
`
`Lynch et a1 patent 4,165,795 also shows an early parallel
`
`10
`
`Lynch argues that maximum fuel efficiency can be
`hybrid drive.
`realized when a relatively small
`internal combustion engine is
`
`provided, such that when the engine is operated at an efficient
`
`speed, it produces approximately the average power required over a
`
`The example given is of an engine producing 25
`typical mission.
`hp maximum and 17 hp at its most efficient speed, about 2500 rpm.
`This is to be combined with an electric motor-generator of about 30
`
`peak hp. This vehicle requires a variableératio transmission to
`achieve reasonable performance. It appears that the engine is to be
`
`run continuously, at a steady speed, with torque provided by the
`
`motor when needed and excess torque used to charge the batteries
`
`torque provided by the motor is
`In a first embodiment,
`otherwise.
`transmitted to the drive wheels through the engine, while in a
`
`second embodiment their respective positions are reversed.
`
`Nishida U.S. patent 5,117,931 shows a parallel hybrid vehicle
`
`where torque from an electric motor may be combined with torque
`from an internal combustion engine in a "torque transmission unit"
`
`for controlling the
`and means
`comprising paired bevel gears
`relative rates of-rotation of the motor and engine, so that the
`
`motor can be used to start.the engine, absorb excess torque from
`
`or provide additional
`charging a battery),
`(by
`engine
`the
`propulsive torque.
`A variable-speed transmission is coupled
`between the torque transmission unit and the propelling wheels.
`Both
`the
`torque
`transmission unit
`and
`the variable-speed
`
`transmission-are complex, heavy, and expensive components,
`
`the use
`
`of which would preferably be avoided.
`6
`
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`N!"n-r-uuq_61'.“-VE'Jh'll'1l
`cmEEEZKZ'
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`30
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`35
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`tale-.1121”?'1'?!”-v--,-.
`
`Helling U.S. patent 3,923,115 also shows
`
`a hybrid vehicle
`
`having a torque transmission unit for combining torque from an
`
`electric motor and an internal combustion engine.
`
`However,
`
`in
`
`the motor and engine
`Helling the relative rates of rotation of
`- input shafts are fixed;
`a flywheel is provided to store excess
`mechanical energy as well as a battery to store excess electrical
`
`energy. Albright, Jr. et a1 patent 4,588,040 shoWs another hybrid
`drive scheme using a flywheel
`in addition to batteries to store
`
`excess energy; various complicated mechanical connections are
`
`provided between the various components. Capacitors have also been
`
`proposed for energy storage; see Bates et al U.S. patent 5,318,142.
`
`Fjallstrom U.S. patent 5,120,282 shows a parallel hybrid drive
`train wherein torque from two electric motors is combined with
`
`torque produced by an internal combustion engine;
`
`the combination
`
`is performed by a complex arrangement of paired planetary gearsets,
`and unspecified control means are alleged to be able to allow
`variation of road speed without a variable-ratio<transmission.
`
`Hunt U.S. Patent Nos. 4,405,029 and 4,470,476 also disclose
`parallel hybrids requiring complex gearing arrangements,
`including
`multiple speed transmissions. More specifically,
`the Hunt patents
`disclose several embodiments of parallel hybrid vehicles. Hunt
`
`that an
`lines 6 - 20 of the '476 patent)
`indicates (see col. 4,
`electric motor may drive the vehicle at low speeds up to 20 mph,
`
`and an internal combustion engine used for speeds above 20 mph,
`
`while "in certain speed ranges, such as from 15 - 30 mph, both
`
`power sources may be energized... Additionally, both power sources
`could be utilized under heavy load conditions." Hunt also indicates
`
`that "the vehicle could be provided with an automatic changeover
`
`device which automatically shifts from the electrical power source
`
`to the internal combustion power source, depending on the speed of
`the vehicle" (col. 4,
`lines 12 - 16).
`
`However,
`
`the Hunt vehicle does not meet the objects of the
`7
`
`f
`
`10
`
`£5-
`i!
`[U
`U?
`
`(5
`1!
`
`26'
`3
`Ed
`in
`53
`an
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`present invention, as discussed in detail below. Hunt's vehicle in
`each embodiment
`requires
`a conventional manual or automatic
`transmission. See col. 2,
`lines 6 - 7. Moreover,
`the internal
`combustion engine is connected to the transfer case (wherein torque
`from the internal combustion engine and electric motor is combined)
`
`conventional
`of
`converter
`torque
`“fluid coupling or
`a
`by
`construction“. Col. 2, lines 16 - 17. Such transmissions and fluid
`
`couplings or torque converters are very inefficient, are heavy,
`bulky, and costly, and are to be eliminated according to one object
`of the present invention, again as discussed in detail below.
`
`Furthermore,
`
`the primary means of battery charging disclosed
`
`by Hunt involves a further undesirable complexity, namely a turbine
`driving the electric motor in generator configuration. The turbine
`is fueled by waste heat from the internal combustion engine. See
`
`lines 10 - 60. Hunt's internal combustion engine is also
`col. 3,
`fitted with an alternator,
`for additional battery charging
`
`capability, adding yet further complexity. Thus it is clear that
`Hunt fails to teach a hybrid vehicle meeting the objects of the
`present
`invention - that is, a hybrid vehicle competitive with
`conventional vehicles with respect
`to performance,
`cost
`and
`complexity, while achieving substantially improved fuel efficiency.
`
`Kawakatsu U.S. Patents Nos. 4,305,254 and 4,407,132 show a
`
`parallel hybrid involving a single internal combustion engine
`coupled to the drive wheels through a conventional variable-ratio
`transmission,
`an electric motor,
`and an alternator,
`to allow
`
`efficient use of the internal combustion engine. As in the Hunt
`disclosure,
`the engine is intended to be operated in a relatively
`
`efficient range of engine~speeds; when it produces more torque than
`is needed to propel the vehicle,
`the excess is used to charge the
`batteries; where the engine provides insufficient torque,
`the motor
`is energized as well.
`
`A further Kawakatsu patent, No. 4,335,429,
`8
`
`shows a hybrid
`
`10
`
`15
`25,
`iii
`re
`
`30
`
`35
`
`"\
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`in this case comprising an internal combustion engine and
`vehicle,
`two motor/generator units.
`A first larger motor/generator, powered
`
`by a battery,
`
`is used
`
`to provide additional
`
`torque when that
`
`provided by the engine is insufficient; the larger motor-generator
`also converts excess torque provided by the engine into elctrical
`
`energy, to be stored by the battery, and is used in a regenerative
`braking mode.
`The second smaller motorlgenerator is similarly used
`to provide additional torque and additional regenerative braking as
`needed.
`
`More particularly,
`
`the latter Kawakatsu patent asserts that
`
`a single electric motor sized to provide sufficient
`
`torque to
`
`propel the vehicle would not be capable of providing sufficient
`
`2 line 8.
`line 50 - col.
`regenerative braking force; see col. 1,
`Accordingly, Kawakatsu provides two separate motor/generators, as
`
`noted; a separate engine starting motor is also provided.
`
`See col.
`
`larger
`the
`shown,
`In the embodiment
`23.
`—
`22
`lines
`6,
`motor/generator is connected to the wheel drive shaft, while the
`
`engine.and the smaller motor/generator are connected to the wheels
`
`three
`complex mechanism comprising
`a
`through
`controllable clutches. See col. 5,
`lines 50 - 62.
`
`separately-
`
`Numerous patents disclose hybrid vehicle drives tending to
`fall into one or more of the categories discussed above. A number
`
`of patents disclose systems wherein an operator is required to
`select between electric and internal combustion operation;
`for
`
`example,
`
`an electric motor
`
`is provided for operation inside
`
`buildings where exhaust fumes would be dangerous, and an internal
`combustion engine provided for operation outdoors.
`It is also
`known to propose a hybrid vehicle comprising an electric motor for
`use at low speeds, and an internal combustion engine for use at
`
`higher speed.
`
`The art also suggests using both when maximum torque
`
`In several cases the electric motor drives one set of
`is required.
`wheels and the internal combustion engine drives a different set.
`
`See generally Shea (4,180,138); Fields et al (4,351,405); Kenyon
`9
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`10
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`35
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`1..)
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`(4,438,342); Krohling (4,593,779); and Ellers (4,923,025).
`
`Many of these patents show hybrid vehicle drives wherein a
`
`variable speed transmission is required, as do numerous additional
`
`references. A transmission as noted above is typically required
`where the internal combustion engine and/or the electric motor are
`not capable of supplying sufficient torque at low speeds. See Rosen
`
`(3,791,473); Rosen (4,269,280); Fiala (4,400,997); and Wu et al
`
`10
`
`shows a vehicle of this general
`(4,697,660). Kinoshita (3,970,163)
`type wherein a gas turbine engine is coupled to the road wheels
`
`through a three-speed transmission; an electric motor is provided
`
`to supply additional torque at low speeds.
`
`For further examples of series hybrid vehicles generally as
`
`discussed above, see Bray (4,095,664); Cummings (4,148,192); Monaco
`
`(4,354,144);
`(4,313,080); McCarthy
`Park
`(4,306,156);
`al
`et
`Heidemeyer
`(4,533,011); Kawamura
`(4,951,769);
`and Suzuki et a1
`
`(5,053,632). Various of these address specific problems arising in
`
`the manufacture or use of hybrid vehicles, or specific alleged
`design improvements.
`For example, Park addresses certain specifics
`
`of battery charging and discharge characteristics, while McCarthy
`shows a complex drive system involving an internal combustion
`
`engine driving two electric motors;
`
`the torque generated by the
`
`1atter_is combined in a complex differential providing continuously
`variable gear ratios.
`Heidemeyer shows connecting an internal
`
`combustion engine to an electric motor by a first friction clutch,
`
`and connecting the motor to a transmission by a second friction
`clutch.
`
`30
`
`35
`
`other patents of general relevance to this subject matter
`include Toy
`(3,525,874),
`showing a series hybrid using a gas
`turbine as internal combustion engine; Yardney (3,650,345), showing
`use of a compressed-air or similar mechanical starter for the
`internal combustion engine of a series hybrid, such that batteries
`of -limited current
`capacity could be used;
`and Nakamura
`
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`Cl
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`10
`
`(3,837,419), addressing improvements in thyristor battery-charging
`and motor drive circuitry.
`Somewhat further afield but of general
`interest are the disclosures of Deane
`(3,874,472); Horwinski
`
`(4,611,466);
`(4,562,894); Keedy
`(4,042,056); Yang
`and Lexen
`Jr.
`(3,623,568); Grady,
`(4,815,334); Mori
`(3,454,122); Papst
`(3,211,249); Nims et a1 (2,666,492); and Matsukata (3,502,165).
`Addititional
`references
`showing parallel hybrid vehicle drive
`
`systems include Froelich (1,824,014) and Reinbeck (3,888,325).
`
`U.S. Patent No. 4,578,955 to Medina shows a hybrid system
`
`wherein a gas turbine is used as the internal combustion engine to
`
`drive a generator as needed to charge batteries. Of particular
`interest to certain aspects of the present invention is that Medina
`
`discloses that the battery pack should have a voltage in the range
`
`of 144, 168 or 216 volts and the generator should deliver current
`
`in the range of 400 to 500 amperes. Those of skill in the art will
`
`recognize that these high currents involve substantial resistance
`
`and additionally require that"a11 electrical
`heating losses,
`connections be made by positive mechanical means such as bolts and
`
`nuts,.or by welding. More specifically, for reasons of safety and
`
`in accordance with industry practice, currents in excess of about
`
`50 amperes cannot be carried by the conventional plug-in connectors
`preferred for reasons of convenience and economy, but must be
`
`carried by much heavier, more expensive and less convenient fixed
`connectors
`(as used on conventional starter and battery cable
`
`connections). Accordingly, it would be desirable to operate the
`
`electric motor of a hybrid vehicle at lower currents.
`
`30
`
`U.S. patent 5,765,656 to Weaver also shows a series hybrid
`wherein a gas turbine is used as the internal combustion engine;
`
`hydrogen is the preferred fuel.
`
`U.S. Patent No. 4,439,989 to Yamakawa shows a system wherein
`two.different
`internal combustion engines are provided,
`so that
`
`35
`
`only one need be run when the load is low. This arrangement would
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`be complex and expensive to manufacture.
`
`Detailed discussion of various aspects of hybrid vehicle
`
`drives may be found in Kalberlah, "Electric Hybrid Drive Systems
`
`for Passenger Cars
`
`and Taxis",
`
`SAE Paper No.
`
`910247
`
`(1991).
`
`Kalberlah first compares "straight" electric, series hybrid, and
`
`5
`
`'
`
`parallel hybrid drive trains, and concludes that parallel hybrids
`
`are preferable, at least when intended for general use (that is,
`straight electric vehicles may be useful under certain narrow
`
`10
`
`conditions of low-speed,
`
`limited range urban driving). Kalberlah
`
`then compares various forms of parallel hybrids, with respect to
`
`his Fig. 4, and concludes that the most practical arrangement is
`
`one in which an internal combustion engine drives a first pair of
`wheels,
`and an electric motor
`the second;
`more particularly,
`£5 ' Kalberlah indicates that mechanical combination of the torque from
`an internal combustion engine and an electric motor is impractical.
`
`E;
`;:
`56
`23
`ES
`:5
`13
`fig
`
`30
`
`follow
`57346,031
`and
`5,301,764
`patents
`Gardner U.S.
`in that Gardner shows separate1y_driving at
`Kalberlah's teachings,
`least two pairs of wheels; one pair is driven by a first electric
`motor, and'the second by‘a second electric motor or alternatively
`by a small internal combustion engine. Three different clutches
`are provided to allow various sources of drive torque to be
`connected to the wheels,
`and to a generator, depending on the
`vehicle's operation mode.
`The internal combustion engine is run
`continuously, and provided the driving torque when the vehicle is
`
`in a cruise mode; at other times it is used to charge the batteries
`powering the electric motors.
`
`"The Technological Constraints of Mass, Volume,
`Bullock,
`Dynamic Power Range and Energy Capacity on the Viability of Hybrid
`and Electric Vehicles",
`SAE Paper No. 891659 (1989) provides a
`detailed theoretical analysis of electric vehicles in terms of the
`
`loads thereon, and a careful analysis of the various battery types
`then available.
`Bullock concludes that a vehicle having two
`
`35-
`
`12_
`
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`J
`i
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`electric motors of differing characteristics, driving the wheels
`
`through a variable-speed transmission, would be optimal
`
`for
`
`automotive use;
`
`see the discussion of Fig. 8.
`
`Bullock also
`
`suggests the use of an internal combustion engine to drive battery
`charging, but does not address combining the engine's torque with
`
`that from the motors; see pp. 24 - 25.
`
`Further related papers are collected in Electrig_and_flyhrid
`yghigle_£eghnglggy, volume SP-915, published by SAE in February
`1992.
`See also, Wouk, "Hybrids: Then and Now"; Bates,
`"On the road
`
`10
`
`with a Ford HEV", and King et a1, "Transit Bus takes the Hybrid
`
`Route", all in IIEELfipectrgm, Vol. 32, 7,
`
`(July 1995).
`
`- Urban et a1 0.5. patent 5,667,029 shows two embodiments of
`
`parallel hybrids; a first embodiment is shown in Figs. 1'4 9 and
`11, and a second in Figs. 12 - 17. Both embodiments have numerous
`
`common features,
`
`including similar operating modes. Referring to
`
`the first embodiment, an internal combustion engine provides torque
`
`to the road wheels or to a generator;
`
`two electric motors can
`
`provide torque to the road wheels, or charge batteries during
`regenerative braking.
`Torque
`from the engine and motors
`is
`
`combined at
`the input shaft
`to a variable—ratio transmission.
`Overrunning clutches are provided, e.g.,
`to allow the engine's
`torque-to be applied to the road wheels without also rotating the
`motors.
`
`As indicated at col. 6,
`
`lines 25 — 54, certain transitions
`
`between various operating modes are made automatically, responsive
`
`30
`
`if the
`for example,
`the accelerator pedal;
`to the position of
`operator does not depress the pedal beyond a given point, only the
`
`internal combustion engine is employed to propel the vehicle; if
`
`the electric motors
`the operator depresses the pedal more fully,
`are also energized. other changes in the operational mode must be
`made by the operator directly;
`for example,
`the vehicle may be
`
`operated as a "straight electric" vehicle, e.g. for short duration
`13
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`a~.___.._*....._....
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`..
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`_
`
`.
`
`trips, by the operator's making an appropriate control action.
`col. 7,
`lines 49 - 56.
`v
`
`See
`
`The Urban et a1 design appears to suffer from a number of
`
`the internal combustion engine is
`First,
`significant defects.
`stated to provide all torque needed to accelerate the vehicle to
`
`lines 3 -
`cruising speed under normal circumstances (see col. 5,
`10), and also to propel the vehicle during cruising (see col. 6,
`
`10
`
`The electric motors are to be used only during
`lines 48 — 54).
`rapid acceleration and hill—climbing; col. 5,
`lines 10 - 13. A 20
`
`horsepower engine, operated through a continuously variable—ratio
`tranamission and a torque converter, is stated to be adequate for
`this purpose.
`Such components are clearly rather complex and
`
`torque converters are notoriously inefficient.
`expensive; further,
`Moreover, using the internal combustion engine as the sole source
`
`of power for low—speed running would require it to be run at low
`
`speeds, e.g., at traffic lights, which is very inefficient and
`
`that
`(Various additional references suggest
`highly polluting.
`excess
`torque can be used to charge batteries;
`if this were
`
`incorporated in the Urban system,
`
`the engine might be run at a
`
`reasonably efficient output level while the vehicle was stationary,
`
`but this would lead to high levels of noise and vibration.
`event Urban does not appear to consider this possibility.)
`
`In any
`
`0n the other hand, Urban does suggest that the vehicle can be
`
`operated as a "straight electric“ under low—speed conditions, but
`
`input;
`this requires the operator to provide an explicit control
`this complexity-is unacceptable in a vehicle intended to be sold in
`quantity, as would be required in order to reach Urban's stated
`goals of reduction of atmospheric pollution and reduced energy
`
`consumption.’
`
`As noted,
`
`hybrid vehicle operation must
`
`be
`
`essentially "foolproof", or "transparent" to the user,
`chance of commercial success.
`
`to have any
`
`Urban's second embodiment is mechanically simpler, employing
`
`14_
`
`30
`
`35.
`
`il
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`u-..-_._.._.___.. __ . ...
`
`but a single "dynamotor",
`
`through which torque is transmitted from
`
`the engine to the variable-ratio transmission, but suffers from the
`
`same operational deficiencies.
`
`A second Urban et a1 patent, 5,704,440,
`
`is directed to the
`
`method of operation of the vehicle of the '029 patent and suffers
`the same indequacies.
`
`Various articles describe several generations of Toyota Motor
`
`Company hybrid vehicles, stated soon to be available commercially.
`See,
`for example, Yamaguchi,
`"Toyota readies gasoline/electric
`
`hybrid system", Automotiye_Engineering, July 1997, pp. 55 - 58;
`Wilson, “Not Electric, Not Gasoline, But Both", Autgfleek, June 2,
`
`1997, pp. 17 - l8; Bulgin, "The Future Works, Quietly", Antgmeek
`
`February 23, 1998, pp. 12 and 13; and "Toyota Electric and Hybrid
`
`Vehicles", a Toyota brochure.
`
`A more detailed discussion of the
`
`Toyota vehicle's
`
`powertrain
`
`is
`
`found
`
`in Nagasaka
`
`et
`
`a1,
`
`"Development of
`
`the Hybrid/Battery ECU for
`
`the Toyota Hybrid
`
`\According to the
`System", SAE paper 981122 (1998), pp. 19 - 27.
`Wilson article, Toyota describes this vehicle as a "series—parallel
`
`hybrid"; regardless of the label applied, its powertrain appears to
`be similar to that of the Berman patents described above, that is,
`torque'from either or both of an internal combustion engine and an
`
`"power—split
`in a
`are controllably combined
`electric motor
`mechanism" and transmitted-to the drive wheels through a planetary
`
`variable—ratio
`a
`of
`functionality
`the
`providing
`gearset
`transmission.
`See the Nagasaka article at pp. 19 - 20.
`
`30
`
`35
`
`Furutani U.S. patent 5,495,906 describes a vehicle having an
`internal combustion engine driving a first set of wheels through a
`variable-ratio transmission and an electric motor driving a second
`
`set of wheels. The engine is apparently intended to be run
`
`to charge
`it drives a generator
`low speeds,
`continuously; at
`batteries providing energy to the motor, and at higher speeds the
`engine or both engine and motor propels the vehicle.
`In some
`15
`
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`circumstances the transmission may not be required; compare, for
`example, col. 3,
`lines 4 - 8 with col. 5,
`lines 59 - 64.
`
`0.5 patent 5,842,534 to Frank shows a "charge depletion"
`control method for hybrid vehicles;
`in this scheme,
`the internal
`
`combustion engine is essentially used only when the state of the
`batteries is such that
`the vehicle cannot otherwise reach a
`
`In normal operation,
`lines 50 — 55.
`See col. 3,
`recharging point.
`the batteries are recharged from an external power source.
`Frank
`also discusses
`two-mode brake pedal operation, wherein mechanical
`
`brakes are engaged in addition to regenerative braking when the
`pedal is depressed beyond a preset point.
`
`U.S. patent 5,823,280 to Lateur et a1 shows a parallel hybrid
`
`wherein the shafts of an internal combustion engine and first and
`
`second electric motors are all coaxial; the engine is connected to
`
`the first motor by a clutch, and the first motor to the second by
`a planetary gearset,
`allowing the speeds of
`the motors to be
`
`varied so as to operate them in their most efficient range.
`col. 4,
`line 57 - col. 5,
`line 60.
`
`See
`
`U.S. patent 5,826,671 to Nakae et al shows a parallel hybrid
`
`wherein torque from an internal combustion engine is combined with
`that from a motor
`in a planetary gearset;
`a clutch is provided
`
`The specific invention relates to sensing of engine
`therebetween.
`wa