`
`est hardship. According to
`UNICEF, 50% of children
`under five are malnour-
`ished and 40% of female
`children do not attend
`school. The government's
`annual per capita invest-
`ment in health and educa-
`tion is approximately $14
`compared to, for example,
`$160 in South Korea. There
`are about 328 million
`people in India who fall be-
`low the poverty line, that is
`with income of less than
`$25 per month.
`The United Nations'
`Human Development In-
`dex ranks India 135th of the
`174 countries listed, well
`below Kenya, Ghana,
`Equatorial Guinea and just
`above Nigeria, Zambia,
`
`and the Republic of the
`Congo (Zaire).
`India has the fourth-larg-
`est foreign debt among sov-
`ereign nations ($93.2 bil-
`lion), with 9% inflation of
`consumer prices.
`India's
`per capita GDP is $340. The
`government spends $420
`million each year to pro-
`mote family planning, ac-
`cording to Secretary of
`Health and Family Welfare
`Y.N. Chaturvedi.
`A large percentage of the
`population is highly edu-
`cated and vocationally
`trained. There are 2 million
`engineers and scientists and
`approximately 50 million
`people with a secondary
`education. Universities are
`graduating more than the
`
`system can absorb and sup-
`port. The remaining popu-
`lation has very little educa-
`tion. India is projected to
`have the largest population
`of illiterates in the world by
`2000.
`Reforms in 1991 and
`1993 have set a new direc-
`tion for the country's for-
`merly closed economy,
`which had been marked by
`complacency. In the past
`few years, the economy has
`been improving with im-
`ports and exports up, finally
`enabling India to join the
`world economy.
`India's 40 million most
`affluent can purchase cars
`either with cash or through
`financing. About 500,000
`citizens are very wealthy by
`
`western standards. By 2000,
`an expanding segment of
`the population (forecast to
`reach 60 million) will be
`able to afford a new or used
`car. Most of the increases
`will come from those who
`currently drive motor-
`cycles, scooters, and mo-
`peds.
`India's vehicle market
`will become very competi-
`tive at a very fast pace. Ve-
`hicle production will place a
`strain on component sup-
`pliers with manufacturing
`plants in remote areas of the
`country. At issue will be the
`transport infrastructure for
`on-time deliveries.
`Raymond Champagne
`Interesting? Circle 159
`Not interesting? Circle 160
`
`Toyota Prius
`
`Toyota has christened its gasoline-electric hybrid car Prius,
`forthcoming frontal 40% offset impact at 56 km/h. Toyota
`taking the name from the company's 1995 Tokyo Motor
`subjected the Prius to its own draconian crash tests, including
`Show concept car. The Prius is said to be Japan's first, and
`a frontal 40% offset crash at 60 km/h, in which the car is said
`one of the world's first, series production internal-combus-
`to have performed extremely well.
`tion engine/electric motor-driven passenger cars. Prius,
`The Prius employs a parallel hybrid system, using both
`according to Toyota, means "pioneering" in Latin. The com-
`the internal combustion engine and electric motor for pro-
`pact four-seat sedan is priced at 2.15 million yen, about
`pulsion. Toyota, by the way, preceded the Prius with a
`$20,000, "Two One" signifying the coming century.
`series hybrid vehicle, an electrically driven mini bus whose
`The Prius is on a new platform, exclusive to the hybrid car
`gasoline engine is used to generate electricity and recharge
`at this time, though it will serve in other small cars. Likewise,
`the battery.
`the type 1NZ-FXE engine shares its basic architecture with
`The type 1NZ-FXE dual-overhead-camshaft, 16-
`the forthcoming replacement of the company's small engine
`valve, inline four-cylinder engine was purpose-de-
`family, the 4E series.
`signed for the hybrid application. It is an extremely
`compact unit, to be installed inline
`The four-door sedan measures 4275 mm
`with the electric motor and
`long, 1695 mm wide, and 1490 mm tall on a
`CVT. The aluminum 1.5-L
`2550-mm wheelbase, and its curb mass
`engine, placed trans-
`is 1515 kg. The Prius' unique styling
`versely, measures 560
`is a creation of Toyota's
`mm long, 595 mm
`CALTY design center in Cali-
`wide, and 680 mm tall,
`fornia. The car's all-steel,
`with a mass of 88.3 kg
`welded integral body
`inclusive of coolant,
`shell was designed to
`lubricant, and air
`Toyota's GOA (global
`cleaner.
`outstanding assess-
`ment) standards, and
`Both the cylinder
`meets the world's
`head and block are
`toughest crash re-
`die-cast in aluminum,
`quirements, includ-
`the latter with thin (2.0
`ing Japan's frontal
`mm) iron liners. The
`and side impacts at 50
`engine has a 75 mm
`km/h and Europe's
`bore to a long 84.7 mm
`
`four-seat sedan, measuring 4275 mm
`Toyota Prius is a compact
`1695 mm wide, and 1490 mm tall on a 2500-mm wheelbase.
`
`long,
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`stroke with a tight bore pitch of 83 mm, and a total displace-
`ment of 1496 cm3. An interesting feature is the adoption of an
`offset crankshaft, whose journal center is 12 mm off the bore
`center, to minimize the piston's side-thrust, for the sake of
`optimum efficiency. The forged crankshaft is fitted with four
`balance weights, attaining a 70% balancing ratio, and is
`supported by five main bearings whose size is 46 mm in
`diameter and 22 mm in width. The pin diameter is 34 mm
`and width 18 mm.
`A single-row, 8.0-mm-pitch roller chain drives dual over-
`head camshafts, a rare practice for Toyota, which seems to
`favor timing belts. Again this method is used for compact
`packaging. The camshaft acts on valves via inverted bucket
`tappets with inner clearance shims. The engine adopts WT-
`i, continuously variable intake valve timing ("i" is for intelli-
`gent, signifying electronic control, which alters the intake
`valve timing for a maximum value of 40° of crankshaft
`revolution). Valve timings are as follows:
`
`Intake valve opens* (deg)
`30 ATDC/10 BTDC
`120 ABDC/80 ABDC
`closes (deg)
`Exhaust valve opens (deg)
`32 BBDC
`2 ATDC
`closes (deg)
`* continuously variable valve timing
`
`The WT-i improves low- and mid-speed torque and fuel
`economy, and reduces exhaust emissions and minimizes
`powertrain vibrations during engine start-up (the vehicle
`normally moves off on electric power, and the engine comes
`in when accelerating).
`The engine operates in the Atkinson/Miller-cycle, em-
`ploying late intake valve closing, thereby obtaining a higher
`charge expansion ratio without resorting to an extraordinar-
`ily high virtual compression ratio, and reducing pumping
`loss. The combustion chamber shape conforms to Toyota's
`recent favorite, the angled squish area design. Valve diam-
`eters are 30.5 mm for intake and 25.5 mm for exhaust.
`The 1NZ-FXE produces 42.7 kW JIS net at 4000 rpm and a
`
`maximum torque of 102 N-m at 4000 rpm on a 13.5:1 compres-
`sion ratio, and is content with unleaded, regular grade gaso-
`line. The engine operates in a relatively narrow and opti-
`mally efficient band.
`The electric motor/regenerator is a permanent magnet,
`synchronous, ac, watercooled type rated at 30 kW at 940-2000
`rpm and 305 N•m peak torque produced at 0-940 rpm. The
`parallel hybrid system employs a separate generator, which
`supplies power to the propulsion motor that recharges the
`battery, and by modulating the amount of electricity gener-
`ated, controls the planetary-gear-type transaxle's continu-
`ously variable transmission function. Both the motor/regen-
`erator and the generator are of Toyota's own design and
`manufacture.
`The transaxle is essentially an electrically controlled CVT,
`by a clever use of a planetary geartrain, whose sun gear is
`connected to the generator, the planetary gear-carrier to the
`engine, and the ring gear to the motor/output shaft. It splits
`driving torque between the engine and motor, and also func-
`tions as a continuously variable transmission.
`The parallel Toyota Hybrid System (THS) operates as
`follows:
`System start: the engine is started. It automatically stops
`when coolant temperature reaches a preset level:
`Low-speed operation: where the engine's efficiency is low,
`it is stopped by fuel cutoff, and the vehicle is propelled by the
`electric motor. The battery supplies electricity.
`Normal operation: the engine's output is split to 1) drive
`the wheels via a torque-split system (CVT), and 2) drive the
`generator whose electricity is supplied via invertor to the
`motor which adds to vehicle propulsion
`High-load operation: as in full acceleration, the battery's
`electricity is added to the motor for increased torque output
`Deceleration: the motor is employed to regenerate electric-
`ity which is stored in the battery.
`
`Instrumentation is digital, in the center top of the
`instrument panel, below which is a multipurpose
`display.
`
`Display shows both the engine and electric motor
`driving the vehicle, with both the battery and generator
`feeding electricity to the motor. Another display
`shows fuel consumption and energy regeneration
`every five minutes, in 50 W•h units.
`
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`The battery's charge level is monitored
`and maintained by bringing in the engine to
`recharge it. Further, the engine is called
`upon to drive the generator to recharge the
`battery, to drive the air conditioning com-
`pressor, and to raise coolant temperature to
`the operating level.
`The battery pack is a high-output nickel-
`hydride type, comprising 240 cells of 12 V
`each, obtaining a total voltage of 2880 V. A
`senior engineer sees a very long life with this
`battery type, not witnessing a single instance
`of failure during his team's long endurance
`test programs.
`The chassis employs front MacPherson
`strut suspension, and a variation of a twist-
`beam design at the rear. The latter is fitted
`with a triple-rubber-bushed toe-control link
`at each mount pivot to the body. A conven-
`tional twist-beam axle tends to assume a toe-
`out attitude when subjected to lateral force as
`in cornering or lane-change because of the
`attaching pivot bushings' elasticity. The toe-
`control links enable true lateral displacement
`of the axle, thereby assuring stability.
`Steering is by rack and pinion, and is elec-
`tronically controlled and electrically assisted
`with an electric motor acting on the pinion
`shaft.
`Front ventilated disc and rear drum brakes
`are combined with ABS and hydraulic servo
`assistance. The THS's regenerative braking
`effect is also incorporated in the total brake
`system. The Prius is fitted with 165/65R15
`tires on lightweight, cast aluminum wheels.
`The front seat belt system includes a pyro-
`technically activated pretensioner and force
`limiter. Dual SRS air bags are standard.
`The Prius' instrumentation is located at
`the top center of the instrument panel, and is
`a digital/graphic display. Additionally
`there is an LCD-color energy monitor in the
`central console, which shows the instanta-
`neous flow of energy within THS (which of
`the propulsion units is/are driving, is the
`battery being depleted or filled). The display
`may also show fuel/energy consumption/
`regeneration in 30 minutes at five-minute
`increments. An optional navigation/infor-
`mation system also uses this display.
`Toyota claims a Japanese 10/15-mode
`fuel consumption of 28 km/L, about 66 mpg,
`which halves consumption of a typical small
`gasoline engine car of comparable perfor-
`mance and size.
`
`Jack Yamaguchi
`Interesting? Circle 161
`Not interesting? Circle 162
`
`Prius' high-output nickel-hydride battery pack (top) is positioned
`between the rear seat and luggage compartment Below is the
`inverter unit, whose electronic elements are of Toyota s own design
`and manufacture, as is the motor regenerator.
`
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