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`.1
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`flamenco 'iout)... .':'.1::ng 4 i 32K5“
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`BEST AVAILABLE COPY
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`A Srligh~Expat'tsion==Flatio Gasoline
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`Engine for the TOYOTA Hybrid System
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`Toshifumi Takaoka**
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`Katsuhiko Hirose*
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`Tatehito Ueda*
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`Yasushi Nouno”
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`Hiroshi Tada**
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`Hiroshi Kanai*
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`Abstract
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`A 50% reductionIn CO: and fuel consumption in comparison with a vehicle with the same engine displace‘
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`ment has been achieved by the newly developed gasoline engine for the Toyota Hybrid System. ThisIs
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`achieved by a combination of an electric motor and an internal—combustion engine that
`is optimized in
`terms of its displacement and heat cycle. Delaying the closing of the intake valve effectively separates the
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`compression ratio and expansion ratio, so that the expansion ratio, which is normally set to 9:1 to 10:1 to
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`suppress knocking, can be set to 13.5:1. Motor~assisted quick start, improved catalyst warm-up, and the
`elimination of light-load firing allow the system to achieve emissions levels that are only one-tenth of the
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`current Japanese standard values.
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`Keywords: hybrid, low fuel consumption, low emissions, low friction, variable valve timing
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`engine output and the motor output by means of a planetary gear sys»
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`tem to control the power split. One notable feature is that because the
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`drive power is the combined power of the engine and the motor. the
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`engine output can be set to a relatively low value without reducing ve-
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`hicle performance. .
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`1.
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`introduction
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`The earth‘s remaining reserves of fossil fuels are said to total approx-
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`imately two-trillion barrels. or about a 50eyear supply. The electric ve-
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`hicle. because of its zero emissions level and the diversity of sources to
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`supply electrical energy. is regarded as a promising automobile for the
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`future. On the other hand. the energy limitations of on~board batteries,
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`which is to say. their inferior energy density in comparison with fossil
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`fuels, has meant that the electric vehicle has remained no more than just
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`one future technology. The intemal-combusrlon/elcctric hybrid system
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`is promoted as a technology that compensates for this shortcoming of
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`the electric vehicle, but it is also the object of attention as a system that.
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`eliminates the problems of the internal-combustion engine.
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`Because the drive energy of the hybrid system comes either from
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`electrical generation by the intcmal-combustion engine or from the en-
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`gine's direct drive of the axle. the efficiency of the engine. the primary
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`power source. strongly influences the efficiency'of the entire system.
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`in the development of the Toyota Hybrid System, a ncw‘gasoline en—
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`gine was developed with more emphasis on thermal efficiency than on
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`specific output. Because priority was given to the total efficiency of
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`the entire system. it was decided that a high-expansion-ratio cycle
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`would be used. and the engine displacement and maximum output
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`were chosen to reduce friction loss. This paper describes the inves-
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`tigative‘proccss and the results that were obtained.
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`Electric
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`path
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`meductiongears
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`power path
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`Hybrid transmission
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`”M
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`Fig. 1 Toyota Hybrid System Configuration
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`Fig. 2 shows the relationship between output and efficiency. One
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`issue for the engine was how to raise the net thermal efficiency from
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`h,
`point A to'point B.
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`2. Hybrid System and Engine Specifications
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`2.1 Hybrid System
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`"x
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`The configuration of THS is shown in Fig. 1. The system links the
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`* Engine Engineering Div. II
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`“ Power Train Engineering Div. ll
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`TOYOTA Technical Review Vol. 47 No. 2 Apr. 1998
`Page 1 of8.
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`2.2 Engine Specifications
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`in order to achieve the thermal efficiency objective. the engine for
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`the hybrid vehicle was planned with the following three points in
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`mind:
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`(l) The only restriction to be placed on the choice of engine displace-
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`ment would be that it be within a range that satisfies the engine
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`oquuI and installability requirements. This makes it possible to
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`use a high-expansiomratio cycle with delayed intake valve clos-
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`53
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`FORD 1107
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`Page 1 of 8
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`FORD 1107
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`

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`VWWWWWww~
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`es. it is possible to reduce friction loss by reducing both the load on
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`the valve system springs and the tensile strength of the piston rings
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`while maintaining the same output.
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`Based on these considerations. the relationship between displace-
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`ment and fuel consumption was calculated. The results are shown in
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`Fig. 5 and Fig. 6. From Fig. 5 it can be seen that in the high-output
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`range, thermal efficiency rises as the displacement becomes larger. but
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`in the low«output range. thermal efficiency is higher with a small-dis-
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`placement engine. Both the indicated thermal efficiency and the me-
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`chanical efficiency (friction loss) improve as displacement becomes
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`larger. but in the low-output range. because of the effect of the pump—
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`ing loss that results from the shift to a partial load. thermal efficiency
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`is better with a small-displacement engine.
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`Fig. 6 shows the relationship between displacement and fuel con-
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`sumption. For the reasons cited above. l500 cc was deemed the opti-
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`mum cngine displacement. given the curb weight of the THS vehicle.
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`5
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`Output (kW)
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`40
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`EZ
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`—C
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`THS vehicle
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`CV
`°8
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`Conventional
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`Average efficiency
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`‘8: Improved engine efficiency
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`A: Optimized engine operating range
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`Engine output
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`Fig. 2 Relationship of Engine Output and Efficiency
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`Netthermalefficiency
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`Fig. 4 Relationship of Displacement and Friction
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`bO
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`BrakethermalefficiencyWe)
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`”Cumulative
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`frequency
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`Cumulativefrequency(sec)
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`50
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`ing. as well as to reduce friction loss by lowering the engine
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`speed.
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`(2) in order to achieve a major reduction in emissions, the engine
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`would operate with )l. = I over its entire range. and the exhaust
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`system would use a 3—way catalyst.
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`(3) Active measures would be taken to reduce weight and ingrease ef—
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`ficiency.
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`Fig. 3 shows the relationship between the SN ratio (the ratio of
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`combustion chamber surface area to combustion chamber volume) and
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`the indicated mean effective pressure. The smaller the SN ratio. the
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`less heat is dissipated into the coolant. raising the indicated mean ef~
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`fective pressure. Since the SN ratio tends to decrease as the displace-
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`ment per cylinder increases. this also raises the indicated mean effec—
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`tive pressure.
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`Fig. 4 shows the relationship between displacement and friction
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`loss in two engines designed to have identical output. Because the
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`maximum engine speed can be set lower as the displacement increas-
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`Pe: Brake mean effective pressure
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`Pi‘sPe+me+pr me: Friction mean effective pressure
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`pr: Pumping mean effective pressure
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`1.40
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`0.26
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`Fig. 3 Relationship of S/V Ratio and Indicated Mean
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`Effective Pressure
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`Fig. 5 Displacement and Engine Efficiency
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`54
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`Page 2 of 8
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`FORD 1107
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`Page 2 of 8
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`FORD 1107
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`

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`A High-Ezrpansion-flatio Gasoline Engine for the TGYOTA llybtid'Sys-tum
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`3.2 Relationship of Mechanical Compression Ratio,
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`Valve Timing, and Brake Thermal Efficiency
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`Before a prototype of the high—expansionvratio engine was built. the cf-
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`fccts ofthe mechanical compression ratio and valve'timing on brake thcr~
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`mal efficiency were studied. An in-line four-cylinder. 2l64-cc Toyota 58-
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`FE engine was used in the experiments.
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`‘ Fig. 9 shows the changes in thermal efficiency with different combina-
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`tions of expansion ratio and valve timing.
`if the expansion ratio is in.
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`creased and intake valve closing is delayed. brake thermal efficiency rises.
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`but it reaches a limit at an expansion ratio of l4.7:l. Also, the maximum
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`value of the brake mean effective pressure drops as the delay in intake
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`valve closing increases.
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`36
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`24
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`1000
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`§
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`5%
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`E" a
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`1200
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`1400
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`Displacement lccl
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`3 ELL .— Brakethermalefficiency(%l
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`Vehicle fuel economy -
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`‘5 .
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`1800
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`Fig. 6 Displacement and Fuel Economy
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`3. Improving Efficiency by Means of High Expansion Ratio
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`3.1 Principle
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`The theoretical thermal efficiency of an equivalent chargecycle is
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`improved by raising the compression ratio. But if the compression
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`ratio is raised in a gasoline engine, the compression end temperature
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`rises, and knocking occurs. To prevent knocking in the high-expa-h-
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`sion-ratio engine. the timing of intake valve closing was delayed con-
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`siderably. thus lowering the effective compression ratio and raising the
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`expansion ratio, which essentially controls the thermal efficiency.
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`Fig. 7 is a pressure-volume (p-V) diagram comparing the high—expan-
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`sion-ratio cycle with the conventional cycle when the charging effi-
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`cicncies of the two are equal. Fig. 8 shows the same sort of compari-
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`$011 when the compression end pressures are equal. When the
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`charging efficiency is identical. delaying the closing of the intake
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`valve raises the maximum pressure and increases the positive work.
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`and also reduces pumping less. With identical compression end pres-
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`sure. increasing the expansion ratio raises the theoretical efficien-
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`Cy‘ilxlxlxlflxfifllll?)
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`High-expansion-
`ratio cycle
`Conventional
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`°“°
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`10000
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`PressuretkPal
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`10
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`Cylinder volume (ccl
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`10
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`Fig. 7 p-V Diagrams with
`Equivalent
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`Charging Efficiency
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`Fig. 8
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`p~V Diagrams with
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`Compreésion End
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`TOYOTA Technical Review Vol. 47 No. 2 Apr. 1998
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`Page 3 of 8
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`i°/o) 20
`Brakethermalefficiency
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`1
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`Brake mean effective pressure Pme (MPa)
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`0.2
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`Fig. 9 Expansion Ratio and Thermal Efficiency
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`Fig. 10 shows the relationship between brake thermal efficiency
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`and brake mean effective pressure under full load. As the expansion
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`ratio increases. the timing advance becomes slower due to knocking.
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`and the brake thermal efficiency drops, but if the intake valve closing
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`35
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`34
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`32
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`intake valve
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`closing delay
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`31 30
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` Brakethermalefficiency(%)
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`1.1
`1
`0.9
`0.8
`0.7
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`Brake mean effective pressure under full load (MP8)
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`Fig. 10 Relationship of Brake Mean Effective Pressure
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`and Thermal Efficiency as Expansion Ratio and
`Compression Ratio Change
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`is delayed at the same time, knocking gradually diminishes and effi-
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`ciency improves. Therefore, if the brake mean effective pressure is al.
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`lowed to fall. the combination of high expansion ratio and delayedvin~
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`take valve closing achieves high efficiency. Fig. 11 is an indicator
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`diagram of actual measured results showing that the heat cycle illus-
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`trated in Fig. 7 and Fig. 8 was achieved.
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`10000
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`Highexpansion»
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`ratio cycle $
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`4.2 Engine Structure
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`Fig. 12 is a transverse sectional view of the high-expansion-r‘.
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`engine. An aluminum-alloy cylinder block. Offset crankshaft.‘”" ;
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`ladder-frame structure are used. The crankshaft has been made tr
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`_ ner and lighter. and the load on the valve system springs has been
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`duced. as has the tensile strength of the piston rings. The connect
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`rod/stroke ratio has been increased, and the intake inertia effect
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`been reduced by using a small intake manifold. The engine also it
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`a slant squtsh combustion chamber. All of these features combtnt
`achieve lighter weight, lower friction. and improved combustion.
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`Conventional Otto
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`cycle
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`Conventional
`i.5-liter engine
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`1000
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`Pressure(kPa)
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`100
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`10
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`10
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`100
`1000'
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`Cylinder volume (cc)
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`Fig. 11 indicator Diagram of Actual Measurements
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`THS engine
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`4' Htgh-expansmn—ratlo THS Engine
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`Fig. 12 Transverse Section of High~expansion-ratio Eng
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`4.1 Basic Specifications
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`5. Experimental Results and Considerations
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`This section summarizes the results of experiments conducte.
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`the l.S-liter high~expansion-ratio engine and some considerations
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`coming them.
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`5.1 Relationship of Expansion Ratio and Brake Ther
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`Efficiency
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`lI
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`Fig.’ 13 shows the relationship of ignition tinung to torque at
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`brake specific fuel consumption (BSFCM Expansion ratios of
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`Hit, and l5:l were comparednand it can be seen that as the ex
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`sion ratio increases, the trace knock ignition timing is delayed. V1
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`15:! expansion ratio. the efficiency improves at the point of mini
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`spark advance for best torque (MBT), but the expansion ratio i
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`striCted by the knocking that occurs due to the high effective com
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`sion ratio. The best results in terms of torque and BSFC wer.
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`taincd with an expansion ratio of l41l.
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`Fig. 14 shows the results of a study of thermal efficiency v
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`engine output. A 14:1 expansion ratio showed the best results
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`the entire output range. Ultimately. an expansion ratio of l3.5:
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`chosen. taking into account such factors as the allowable variati
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`Table 1 shows the main specifications for the high-expansion—ratio
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`engine. The mechanical compression ratio is set to l3.5:l. but the ef-
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`fective compression ratio is suppressed to the range of 4.8:1 to 9.321
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`by using intelligent variable valve timing (VVT-i) to time the intake
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`valve closing between 80° and 120° after bottom dead center (ABDC).
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`The ratio of 4.821 is obtained by the maximum delay of VVT~i and is
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`used to counter vibration during engine restart. as explained below.
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`Table 1 Design Specifications
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`Engine model
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`iNZ-FXE
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`30cc
`Combustion chamber volume
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`Mechanical compression ratio
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`13.5
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`Eltective compression ratio
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`intake valve closing timing
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`Exhaust valve opening timing
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`4~S~9~3
`80~120°ABDC
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`32° gene
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`56
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`A 'H'iq'n—E¥nansiun-Ratiu uaxgiine Engine. for the (ovum: Hynrm Sysgcm
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`h
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`combustion chamber volume and the adhesion of deposits in the com—
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`bustion chamber. in order to leave a margin for pre~ignition.
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`ventional engines and that the objective of reducing friction loss was
`achieved.
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`1000 rpm
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`Black points are trace knock
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`80
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`intake valve
`A closing
`a seam
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`80
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`ABDC
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`260
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`A1:
`a<
`9)
`240 U1L.
`inCD
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`220
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`120
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`100
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`80
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`EE
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`Q)3
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`EOy.
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`.
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`Expanston ratio
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`O
`U
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`14
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`70
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`60
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`280
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`250
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`240
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`Ignition advance (degrees BTDC)
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`I
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`inin
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`EE g
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`E +
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`9
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`EB
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`E 8
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`Fig. 13 Relationship of ignition Timing and BSFC
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`1000
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`2000
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`3000
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`4000
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`Engine speed (rpm)
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`aO
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`(Jm
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`Fig. 15 Torque Improvement Effect of VVT-i
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`y.
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`0.2
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`0.1
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`TSD.
`25,
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`82 ‘
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`5
`.13
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`i
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`Expansion ratio
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`0
`13
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`14'
`D
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`A
`15
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`40
`30
`20
`10
`50
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`Engine output (kwl
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`0
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`Brakethermalefficiency(We) c:Q
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`1600
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`3200
`_ 4500
`6400
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`Engine speed (rpm)
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`I
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`Fig. 14 Expansion Ratio and Brake Thermal Efficiency
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`5.2 Torq’ue improvement by VVT-i
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`o
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`Full-load torque was adjusted using VVT-i. The results are shown
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`in Fig. 15. An improvement in torque of 10% or more was made pos-
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`sible by advancing the intake valve ciosing by 10".
`In THS. the en
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`gine is controiled so that intake valve closing is advanced when the
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`load requirements are high.
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`5.3 Friction Loss
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`As stated previously, the engine speed was lowered in an attempt to
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`reduce friction loss. The measured results are shown in Fig. 16.
`it
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`can be seen that the friction loss for the highfexpansionwatio engine is
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`31 u Consistently lower level than the cluster of points plotted for con~
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`TOYOTA Technical Review Vol. 47 No. 2 Ap'r. 1998
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`Page 5 of 8
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`Fig. 16 Comparison offriction Loss "
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`' A
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`5.4 Reduction of Exhaust Emissions
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`The advantages and disadvantages of the hybrid vehicle with re
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`spect to cleaner exhaust emissions are summarized below
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`Advantages
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`l) By using the supplementary drive power of the electric motor, the
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`system eliminates the iight~load range, where concentrations of
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`hydrocarbons in the emissions are high and the exhaust tempera-
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`ture is low.
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`57
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`200
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`(“Cl
`Catalystbedtemperature
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`Engine stopped
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`Idling at 1000 rpm
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`Time (min.)
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`Fig. 18 Change in Catalyst Bed Temperature with
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`Engine Stopped
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`10 . 15 mode
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`i0
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`Conventional
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`.0on
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`.0& HC
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`HCcoNOxlg/kml
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`Fig. 19 Comparison of Emissions at Catalyst Inlet
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`5.5 Vibration Countermeasures When Starting an
`Stopping
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`Stopping the engine when the vehicle stops contributes greatly,
`fuel economy. realizing a 20% improvement in the 10-15 mode.
`(
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`the other hand, problems have been raised with vibration as the engi
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`speed passes through the resonancei‘point of the drive train, as well
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`vibration due to the brief continuation of the compression and expa
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`sion cycle when the engine stops. The drive train fesonance proble
`is solved by using the motor to raise the enginelspeed in a short
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`time.
`It was thought that the compression and expansion cycle c0t
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`be moderated by reducing the voltime of air when the engine is st
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`off. The VVT-i function is used to reduce the volume of the intake 2
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`Fig. 20 shows floor vibration when the engine starts. The large a
`plitude of acceleration seen in area A in the diagram is due to the co
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`pression reaction force. This amplitude can be reduced considerably.
`shown in area A’. by using VVTJ to set the timing of intake valve cl~
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`ing to 120° ABDC. The vibration seen in area B arises from the ra;
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`increase in engine torque after the engine‘ starts firing. This is elimin
`ed by controlling the ignition timing delay, as shown in area B“.
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`FORD 1107
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`(2) By allocating a portion of the load to the electric motor. the System
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`is able to reduce engine load flucwation under conditions such as
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`rapid acceleration. This makes it possible to reduce quick transients
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`in engine load so that the air-fuel ratio can be stabilized easily.
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`Disadvantages
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`(l) Because the engine is used in the high—efficiency range. the ex-
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`haust temperatures are lower than for a conventional vehicle.
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`(2) There is concern that the more the engine is stopped and restarted,
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`the more unburned fuel will enter the exhaust system and the more
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`the catalyst bed temperature will drop.
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`Fig. 17 shows the exhaust temperature distribution for the high-ex—
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`pansion-ratio engine. Although the exhaust temperatures are lower
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`than for a conventional engine, a minimum temperature of 400°C is
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`ensured for the engine operating range shown in the diagram. This is
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`a temperature that can maintain the catalyst in an activated state.
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`Fig. 18 shows the change in the catalyst bed temperature after the
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`vehicle stops.
`In a conventional vehicle. where the engine continues
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`to idle. the catalyst bed temperature slowly drops. But in the THS ve—
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`hicle. the influx of low-temperature exhaust gases can be avoided by
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`stopping the engine. making it possible to sustain a comparatively
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`gradual'decline in temperature.
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`Fig. 19 shows the levels of exhaust gases at the catalyst inlet.
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`Hydrocarbons are at the same level as a conventional vehicle. which is
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`thought to be due to the smaller volume and higher SN ratio of the
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`combustion chamber. However, as explained previously. the catalyst
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`is maintained in an activated state that is sufficient to ensure a high
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`rate of catalytic conversion.
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`Exploiting the advantages cited above based on these results.
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`Toyota optimized the system to achieve the voluntary emissions target
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`of one-tenth of the current standard values.
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`THS engine operating range
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`120
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`60
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`40
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`20
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`EE g
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`D“
`5s...
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`100 80
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`Exhaust temperature l°Cl
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`0
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`800
`1600
`2400
`3200
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`Engine speed (rpm)
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`4000
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`Fig. 17 Exhaust Temperature Map
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`58
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`Page 6 of 8
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`Page 6 of 8
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`FORD 1107
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`in xJ .4) :2 9)- z: .i :3 a,
`.zio Gasoline Engine for the TC‘;’CT.'-. Hybrid System
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`:
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`intake valve
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`intake valve closing timing
`90°
`AEOC
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`114°
`OPIO
`125°
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`73"
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`intake valve
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`. ...........
`closing 120°
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`WW,-
`//////:[(/#§$‘////'/_///fl/////l‘//////
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`,- “
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`g.
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`.....
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`"
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`1"
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`800
`400
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`Engine speed lroml
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`1 200
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`0
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`Cylinderpressure(MP8)
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`Fig. 20 Vibration When Engine Starts
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`Fig. 21 Relationship of Engine Speed and Cylinder
`Pressure
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`\ EC
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`§
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`.9
`E
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`g
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`8
`<
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`closing 90"
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`Intake valve
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`closing 120°
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`A800
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`:3
`to E
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`E
`vC
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`.2
`0
`5
`2
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`§
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`<
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`~10
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`E
`9 1000‘
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`vQ0CLin
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`0
`.EG
`j
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`-O.2
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`0
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`0.2
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`0.4
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`Time (see)
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`0.6
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`078
`1
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`5.6 Low-temperature Starting
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`In the THS system. the generator is used as a starter motor to sum
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`the engine turning. For this purpose. the generator uses the large-ca-
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`pacity nickel-metal hydride battery as a power supply. However. as
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`the temperature drops. the battery power also drops. reducing the
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`cranking speed. On the other hand. the significant delay in intake
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`valve closing in the high-expansion~ratio engine reduces the compres»
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`sion end pressure (the maximum pressure within the cylinder) during
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`cranking. The relationship between cylinder pressure and engine
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`speed is shown in Fig. 21, using intake valve closing timing as a para»
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`meter. Given the combustion characteristics of the engine, the maxi-
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`mum pressure at which ignition is possible is approximately 0.85
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`MPa. In the THS system. the engine speed and intake valve closing
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`timing are coordinated so that this pressure is maintained even under
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`low-temperature conditions.
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`6.7 Vehicle Fuel Economy
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`.,,.i..__-._..-........—.W
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`efficiencyWe) CumulativeBrakethermal frequency(sec;
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`Ii0
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`20
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`Engine output (will
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`Fig. 22 Engine Operating Range and Efficiency in
`10~ 15 Made
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`(km/liter)
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`Fueleconomy
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`Charge balance (Ah)
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`TOYOTA Technical Review Vol. 47 No. 2 Apr. 1998
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`Page 7 of 8
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`59
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`FORD 1107
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`Fig. 23 Charge Balance and Fuel Economy
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`Fig. 22 shows the efficiency distribution of the developed high-ex-
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`pansion-ratio engine when it is combined with the THS system and
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`driven in the 10 .
`l5 mode.
`in the low-output range the engine is
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`stopped, so that it is used only in the high-efficiency range. Fig. 23
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`shows the relationship between fuel economy and the charge balance
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`of the battery before and after mode driving.
`In the hybrid vehicle, the
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`fuel economy changes as the battery charges and discharges, so the
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`vehicle’s fuel economy is defined as the value when the charge bal~
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`ance is zero.
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`Optimization of the vehicle‘s integrated controls. including regener-
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`ative braking. allows the THS vehicle to attain almost twice the fuel
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`economy of a conventional vehicle of the same class.
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`FORD 1107
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`10.9437458
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`(l0)Shinichi Sarto. Kamiyama, Ueda: improving Thermal Efficiei
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`by Means of Cylinder Bore and Offset Crankshaft. JSAE Prin
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`Materials for Presentations 966 l996-IO
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`I Authors
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`T. TAKAOKA
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`Y. NOUNO
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`{(9% 292-0; [on
`V“).
`914/6?) 2w 429% 625?}
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`F5 We
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`6. Conclusion
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`A lightweight. compact. high«expansion-ratio gasoline engine was
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`developed for use in the internaLcombustion/electric hybrid vehicle.
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`(l) The engine output required to meet the vehicle's weight and per-
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`formance requirements was determined, and the engine displace.
`ment was chosen to yield the optimum vehicle fuel economy from
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`the high~expansion~ratio cycle.
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`(2) A l.5~liter high—expansion-ratio gasoline engine was developed as
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`the primary power source. and it attained the target fuel consump‘
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`tion rate of less than 230 g/kWh.
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`(3) Emissions levels much lower than the current standard values
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`were attained by optimum control of the motor and engine.
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`(4) Vibration during engine starting and stopping was greatly reduced
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`by using VVTsi.
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`(5) The hybrid system achieved twice the fuel economy of a conven~
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`tional vehicle of the same class. while cutting the volume of CO:
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`emissions in half.
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`The authors wish to express their reSpectful appreciation to all
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`those who cooperated in the development of this system. We particu~
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`larly wish to express our gratitude to the late Mr. Masahito Ninomiya
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`for helping us to succeed in providing this engine to our~customers.
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`l References
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`(I) Yoshihiro Fujiyoshi, Urata, Suzuki, Fukuo: Study of. Non-
`
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`Throttling Engine Using Early Intake Valve Closing Mechanism.
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`Repon No.
`l. Society of Automotive Engineers of Japan (ISAE).
`
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`Printed Materials for Presentations 924006. 924 l992-10
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`(2) Shinichi Nagumo. Hara: improved Fuel Efficiency by Control of
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`Intake Valve Closing Timing. JSAE Paper 954092l, Vol. 26 No.
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`4. October. 1995
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`(3) Richard Stone. Eric Kwan: Variable Valve Actuation Mechanisms
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`and the Potential for their Application. SAE Paper 890673. 1989
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`(4) T. Ahmad, M. A. Theobald (GMR): A Survey of Variable.Valve~
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`Actuation Technology. SAE Paper 891674, 1989
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`(5) T. W. Asmus: Valve Events and Engine Operation. SAE Paper
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`820749. l982
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`(6) Hitomi Mitsuo, Sasaki, et al.: Mechanism of improving Fuel
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`Efficiency by Miller Cycle and its Future PmSpects. SAE Paper
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`950974, l995
`
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`(7) James H. Tuttle: Controlling Engine Load by Means of Early
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`intake-Valve Closing. SAE Paper 820408. l982
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`(8) R. A. Stein, K. M. Galietti. T. G. Leone: Dual Equal VCT»A
`
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`Variable Camshaft Timing Strategy for improved Fuel Economy
`
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`and Emissions. SAE Paper 95975. 1995
`.
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`(9) Naoham Ueda. Ichirnaru. Sakai. Kanesaka: High Expansion Ratio
`
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`Gasoline Engine Using Rotary Valve for intake Manifold Control.
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`Report No. 3. JSAE Printed Materials for Presentations 946 W94-
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`60
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`Page 8 of 8
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`FORD 1107
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`Page 8 of 8
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`FORD 1107
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