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`$4033?
`
`The development and Pertormance or the
`AMEhibian Hybrid Electric Vehicle
`
`Gregory W. Davis, Gary L. Hodges, and Frank C. Madeka
`United States Naval Academy
`
`AB STRACT
`
`the
`and the results of
`The design specifications
`performance and emissions testing are reported for a series
`Hybrid Electric Vehicle(I—lEV) which was developed by a
`team of midshipmen and faculty at the United States Naval
`Academy. A S-door Ford Escort Wagon with a manual
`transmission was converted to a series drive hybrid electric
`vehicle. The propulsion system is based on a DC motor
`which is coupled to the existing transmission. Lead-acid
`batteries are used to store the electrical energy. The auxiliary
`power unit(APU) consists of a small gasoline engine
`connected to a generator. All components are based upon
`existing commercial technology.
`
`INTRODUCTION
`
`A series Hybrid Electric Vehicle(l-[EV) has been
`developed by a team of midshipmen and faculty at the United
`States Naval Academy for use in the Hybrid Electric Vehicle
`Challenge which took place during June of 1993.
`This
`competition,
`involving
`thirty
`universities
`from North
`America, was jointly sponsored by Ford Motor Company, the
`SAE International, and the U. S. Department of Energy. A 5-
`door Ford Escort Wagon with a manual
`transmission has
`been converted to a series drive hybrid electric vehicle. The
`propulsion system is based on a DC motor which is coupled
`to the existing transmission. Lead-acid batteries are used to
`store the electrical energy. The auxiliary power unit(APU)
`consists of a small gasoline engine connected to a generator.
`The AMPhibian is designed to be an economically feasible
`HEV, for use in near term applications. To accomplish this,
`all
`components
`are based upon
`existing
`commercial
`technology. Further, this vehicle was designed to retain, to
`the greatest degree possible. the basic driving characteristics
`of a conventional gasoline powered vehicle.
`
`DESIGN OBJECTIVES
`
`The challenge involved many aspects including cost
`effectiveness, acceleration,
`range,
`safety, and emissions,
`which were incorporated into the vehicle design.
`COST - Since the AMPhibian was designed to be
`economically feasible, minimizing cost was considered to be
`a major design goal. All design decisions were made only
`after the associated costs were analyzed. To help attain this
`goal, all components were based upon existing, available
`technology.
`PERFORMANCE AND EMISSIONS — The major
`performance and emissions design goals for the AMPhibian
`include 1) the ability to travel 64 Km as a zero emissions
`vehicle(ZEV) using battery power alone, 2) operating in
`hybrid mode, the ability to travel 320 Km while meeting the
`transitional
`low emissions vehicle(TLEV)
`air pollution
`standards, 3) achieve a time of under 15 seconds when
`accelerating from D to 70 Kph, and 4) climb a minimum of a
`15% grade.
`The vehicle was also to maintain driving
`characteristics as similar to that of conventional gasoline
`powered vehicles as possible(e.g. one brake pedal, shift gears
`normally, etc).
`RELIABILITY AND DURABILITY — The AMPhibian
`
`should have reliability and durability similar to that of a
`conventional gasoline powered vehicle.
`Using existing
`components not only helps to limit the Costs, but also to help
`ensure reliable and durable operation of the vehicle.
`SAFETY - Occupant safety was a prime concern. The
`frontal
`impact zone and original vehicle bumpers were
`maintained to provide sufficient collision protection. The
`original power—assisted braking system also remained intact
`to ensure proper braking. A fire suppression system was
`added to the vehicle and battery compartments, as well as to
`the engine bay to minimize the chances of injury and
`equipment damage. Due to the additional vehicle weight, the
`roof structure was augmented to provide additional protection
`in case of a vehicle roll—over. Finally, the competition rules
`required the use of a five point harness system for both the
`driver and passenger.
`WEIGHT - One major disadvantage of electric vehicles
`has traditionally been the large weight due to the propulsion
`
`3
`
`

`

`batteries required to provide the energy storage capability for
`extended range. An advantage of' the HEV concept is to
`allow for less energy storage capability of the batteries by
`replacing some of these batteries with a small auxiliary
`power unit(APU) which provides the equivalent amount of
`energy with less weight. However, battery weight is still
`considered to be a major concern, requiring the team to
`consider all options for reducing vehicle weight.
`The
`AMPhibian was designed to weigh less than the gross vehicle
`weight rating(GVWR) of the l992 Escort LX Wagon plus an
`additional 10%.
`This results in a maximum allowable
`
`vehicle mass of 1729 kg. Further, to maintain acceptable
`handling,
`the side-to~side bias must remain within 5% of
`neutral, and the front-to-rear bias must not drop below about
`40%]60%.
`PASSENGERS AND CARGO - The HEV carries one
`
`driver and one passenger, along with a volume of cargo(50
`cm by 100 cm by 25 cm). The total combined weight of
`people and cargo is a minimum of 180 kg.
`BATTERY CHARGING - The HEV charging system
`was designed to recharge the battery pack in six hours. This
`should reduce daytime charging demand on electrical
`utilities.
`Daytime
`charging,
`if necessary,
`could be
`accomplished using the APU. The charging system accepts
`either 110V or 220V, 60 Hz AC power.
`STYLING — Vehicle styling changes were minimized to
`maintain continuity with existing vehicle designs.
`No
`external glass or body sheet metal was modified except to
`provide additional ventilation.
`
`VEHICLE DESIGN
`
`The relationship of the design goals was studied, and
`compromises were made to provide near optimal system
`design, given the severe budgetary and time constraints. This
`process resulted in the selection and design of the major
`vehicle components. The following discussion details the
`design decisions
`and vehicle specifications which are
`summarized in table 1.
`
`POWERTRAIN - The Alt/[Phibian is propelled using a
`series drive configuration. That is, the only component that
`is mechanically connected to the drive-train of the vehicle is
`the electric motor. This arrangement is depicted in fig. 1, a
`more detailed electrical schematic is shown in fig. 2. This
`arrangement was considered to be superior to the parallel
`drive arrangement, in which both the electric motor and the
`APU can propel the vehicle, for the following reasons. The
`series drive would require less structural change to install,
`and thus provide a lower cost. The parallel drive system
`would also require a more sophisticated control system to
`minimize driveability problems such as those associated with
`the transition from electric vehicle(EV) mode to hybrid
`electric vehicle(l-iEV) mode. This would, again, result in
`higher cost, and, possibly, reliability problems due to the
`added complexity.
`The conversion to a series drive system required the
`removal of the standard Escort engine. Since the Escort has
`front-wheel
`drive,
`the
`standard
`engine
`is mounted
`
`Table 1. Summary of Components used in the U. S. Naval
`Academy‘s Hybrid Electric Vehicle.
`
`‘92 5 -door Escort LX
`
`1572 kg
`1729 kg
`
`180 kg
`General Electric model
`SBT1346B50
`Curtis PMC 122113—1074
`
`10 arranged in series,
`IZVDC Trojan SSH(P)
`120 VDC
`
`Briggs and Stratton
`Vanguard V-twin, 13.4 kW
`@3600 RPM, two cylinder
`Fisher Technology, Inc.,
`13.5 kW, 150 Vpeak
`Goodyear Invicta GL
`P175/65R14, low rolling
`resistance
`
`$26,000
`
`Chassis:
`Stock GVWR:
`Converted GVWR:
`
`Maximum Carrying
`Capacity( passengers
`and cargo):
`DC Motor:
`
`Motor Controller:
`Batteries
`
`(propulsion):
`
`Bus Voltage:
`APU Engine:
`
`APU Alternator:
`
`Tires:
`
`Estimated Vehicle
`Cost:
`Conversion
`
`Component Net Cost:
`(exc. safety items,
`credit for 1.91% ine
`
`$14,000
`
`transversely in a transaxle arrangement. Thus, the transaxie
`was left intact so that a new axle would not need to be
`
`designed. The electric motor was attached directly to the
`existing bell-housing and flywheel. This arrangement also
`allows full use of the existing transmission, thus allowing for
`variable gear ratios. This was considered an advantage since
`it would allow the electric motor to be operated closer to its
`preferred operating speed over varying vehicle speeds.
`Prior vehicle testing and simulation indicated that the
`vehicle would require a power of approximately 9 kW in
`order to maintain a steady 80 Kph. Acceleration from a
`stand still to 72 Kph in less than 15 seconds would require a
`peak power of 32 KW(at approximately 35 Kph) for a short
`
`
`
`Fig. 1. Series Drive Diagram for the U. S. Naval Academy's
`Hybrid Electric Vehicle.
`
`58
`
`4
`
`

`

`Ancients:
`Push Button
`Accelerator
`PM”
`Ignition Key Activator!
`Pct
`
`Slinky cur-cu
`Santana Switch
`Mall
`urn-Int Shunt
`
`561165
`Hater
`
`Fig. 2. Electrical Schematic for the U. S. Naval Academy's Hybrid Electric Vehicle.
`
`duration. Motor controller cost and availability became the
`critical design factor for the selection of both the type of
`motor and the system operating voltage. The use of an AC
`motor was investigated due to its inherently higher power
`density compared to a DC system. However, it was rejected
`due to the cost, availabiIity,
`size, and weight of
`the
`associated motor controiler. A series connected, 15.2 kW(@
`90 VDC) DC motor was chosen instead since DC motor
`controllers are more widely available, less costly, and fighter
`in weight. The combination DC motor and controller weighs
`approximately 82 kg, the engine that was removed weighed
`113 kg, thus resulting in a net weight savings of 31 kg.
`Although the steady state rating is less than the peak incurred
`during the acceleration, the motor can provide a peak power
`2-3 times its steady state rating for short duration. A
`controller rated at 120 VDCGGO V peak) was chosen, thus
`this determined the system operating voltage.
`BATTERY SELECTION - The AMPhibian has two
`
`battery power systems. One system is at 12V and one at
`120V. The 12V system is used to power the 12V lighting
`and accessories. The 120V primary battery powers the prime
`mover and supplies power to recharge the 12V battery.
`The battery selection was overwhelmingly driven by
`cost considerations. Secondary considerations included:
`1)
`the I—IEV Challenge constraint of 400V or less battery stack
`voltage, 2) the motor controller rating of 120V, 3)
`the HEW
`Challenge constraint of no more than 20 kW—hr capacity at a
`3 hr discharge rate, 4)
`the gross vehicle weight rating
`constraints and 5) practical considerations.
`In general, an
`inexpensive, small, lightweight battery having high specific
`power and high specific energy is desired for use in the
`AMPhibian. Additional considerations included the desire to
`
`maximize voltage thereby minimizing power losses due to
`the lower operating currents. Also, to help to maximize
`electrical energy storage capacity, and,
`therefore, ZEV
`capabilities,
`the
`battery
`ampacity
`rating
`should
`be
`maximized.
`Since the maximum rating for
`the motor
`controller
`is 120V, 120V was selected.
`All order-of-
`magnitude calculation of
`the costs of batteries having
`characteristics superior to those of conventional
`lead—acid
`
`selection
`limit
`team to
`design
`the
`lead
`batteries
`to off-the-shelf
`lead-acid batteries. For
`considerations
`example, Nickel-Iron batteries were found at a cost of $1800
`per six volt battery or $36,000 for a 120V battery stack.
`Nickel-Cadmium were found at a cost of $964 per six volt
`battery or $19,280 for a 120V battery stack. Both estimates
`far exceeded AMPhibian budget constraints; therefore only
`lead-acid batteries were considered.
`
`The task of battery selection was complicated due to the
`general lack of published, comprehensive, technical battery
`performance data covering an extensive number of battery
`models and manufacturers which had been verified by an
`independent source. This limited information resulted in the
`selection of the Trojan SSE-KP) battery. The Trojan SSH(P)
`battery is a deep-cycle, wet-ceiled, 12V battery. The "L"
`type terminals were selected for this application. With the
`primary battery selected,
`the 12V system needed to be
`defined and selected.
`_
`
`Several approaches were considered to power the 12V
`system. This included the extremes of using the existing 12V
`system, as is, or converting all 12V components to 120V.
`Engineering judgment
`indicates the latter option is not
`practical. One approach for providing power to the 12V
`system was to utilize the output of one twelve volt battery
`from the 120V stack. This approach has the advantage of
`simplicity. One disadvantage of this approach is that, using
`the existing 12V components which are grounded to the
`chassis, means that the battery stack is no longer electrically
`isolated from the chassis and, thus, the chance of injury in the
`event of failure is increased. Another problem, is that, since
`the batteries are connected in series, if the battery used for
`the 12V system fails. the whole battery stack will become
`inoperable. The chance of battery failure can be reduced by
`inserting a higher amp-hr rated battery into the 120V stack to
`campensate for the added use. The disadvantage is that this
`local change to the series of batteries imparts an unknown on
`the primary battery
`stack performance
`(i.e.,
`internal
`impedance and resistance). This lead to the decision to have
`two separate battery systems, a 120V primary system and
`separate 12V system.
`
`5
`
`

`

`Several options were considered for the 12V system. One
`option was to incorporate a single, independent high amp-hr
`rated battery required to provide several hours at a relatively
`high discharge rate (e.g., driving at night and in rainjuse of
`head lights and wipers).
`This battery would then be
`recharged externally during refueling andjor
`recharging.
`This option was rejected due to the resulting high weight of
`the battery. A DCJ'DC converter, powered by the 120V stack,
`could be used to meet all of the 12V demand. However, this
`converter must meet the peak 12V load, which is estimated to
`be 210 amps during starting of the APU. This option was
`rejected due to the heavy weight and size of this converter.
`A DC/DC converter, sized to handle the sustained accessory
`loads under moderate to heavy use, was incorporated in
`parallel with a small 12V battery, sized to accommodate the
`APU starting loads.
`This design saves both space and
`weight. The estimated sustained load encountered during
`moderate to heavy accessory use is 20A. However, a 30
`amp DC/DC converter was selected to accommodate the
`future addition of a climate control system for the passenger
`compartment. The APU starter requires a battery rated at
`210 cranking amps. The ultra light Pulsar Racing Battery,
`offered by GNB Incorporated, was used since this battery
`weighed only 4.5 kg, or approximately 50% less than other
`conventional lead—acid batteries, and provides 220 cranking
`amps. AMPhibian's net 12V accessory system, occupies the
`same volume as
`the OEM 12V battery, but weighs
`approximately 9.5 kg less than the OEM battery alone.
`design
`AUXILIARY POWER UNIT
`—
`The
`specifications for
`the auxiliary power unit
`(APU) were
`derived from the mechanical power necessary to achieve the
`320 km desired range while maintaining highway speeds, and
`allowing for reasonable accelerating and coasting time
`periods with the batteries at 20% of' full charge at
`the
`beginning of APU operation. Calculations based on these
`estimates of driving conditions (drag and rolling resistance)
`and drivetrain efficiency resulted in a minimum desired
`electric power availability of 10 kW.
`If the APU could
`deliver this power,
`the HEV would be able to sustain
`highway speeds for the full range, limited only by the amount
`of onboard fuel. However, this power capability alone would
`not allow for reasonable accelerations over this distance.
`
`Therefore, the APU must be capable of charging the batteries
`while at highway speeds so that if acceleration becomes
`necessary, the power may be drawn from both the batteries
`and the APU.
`
`The total calculated electrical requirement resulted in a
`specification of 12.5 kW output from the APU. Estimating
`the overall efficiency of the APU to be 80%, the engine then
`must be capable of mechanically developing 15.6 kW.
`With the design parameters determined, the selection of
`the actual components centered around availability of "shelf"
`items, size and space limitations, emissions and ultimately
`and most significantly the cost.
`Ideally an engine-generator
`set could be found meeting all the requirements. However, a
`review of the available market provided no likely candidates,
`particularly in terms of weight and space requirements.
`Therefore, the engine and generator were selected separately.
`
`Based upon time constraints and availability, the design
`team limited the choice to a conventional, gasoline powered
`spark—ignited engine. Briggs & Snatton donated a 13.5 kW
`"Vanguard" series engine. Although this engine did not meet
`the expected power demand, cost considerations dictated its
`use. Speed is regulated by a governor to 3600 RPM and is
`adjustable. This engine weighs 40 kg, fits under the hood,
`and has a pull~cord starting mechanism. To meet TLEV
`emissions requirements the APU exhaust is Connected to a
`catalytic converter which contains
`a. ceramic monolith
`subslrate. The outlet of the catalytic converter will then lead
`to the existing vehicle exhauSt system. An electrically driven
`air pump was added to provide fresh air for the catalytic
`converter after light-off to ensure complete oxidation of un-
`burned hydrocarbons and carbon monoxide.
`To meet
`the electrical
`requirements, a number of
`alternatives involving both AC and DC generation were
`explored. To minimize space and weight,
`a custom built
`alternator was considered the best choice. Although this was
`the most expensive component of the vehicle, an off-the-
`shelf item was unavailable. A vendor was contracted to build
`
`a custom 13.5 kW, 150 V , 3 phase alternator. The voltage
`was selected based on providing 144 V DC from a three
`phase bridge rectifier, the maximum recommended charging
`voltage for a 120 V battery stack. However, this voltage is
`well above the rated voltage for the controller. Therefore, a
`50 watt 130 V zener diode is used to limit the controller
`
`voltage while charging. Additional voltage control can be
`obtained by varying the speed of the APU. Beside meeting
`all electrical requirements,
`this alternator weighs only 4.6
`kg,
`is 0.276 m in diameter and when mounted directly on the
`APU shaft, extends a mere 0.19 m from the engine block,
`making it the most feasible option.
`The strategy for controlling the APU was developed for
`manual operation and will be incolporated into a digital
`control system with a goal of making driving the HEV as
`much like driving a conventional vehicle as possible. The
`system must sense battery voltage to determine battery
`condition and control
`the APU operation.
`It must also
`control ancillary functions such as insuring the battery box
`exhaust fan is on whenever charging and monitoring APU
`current to prevent overload.
`A three position switch was mounted in the passenger
`compartment to start or stop the APU or place control in the
`strategy mode. The first two positions are self explanatory
`and will override the strategy mode, allowing the driver to
`make the decision to start or stop the APU while monitoring
`battery voltage, motor and APU current along with other
`pertinent parameters. However, while in the strategy mode,
`the system will be make decisions and carry out programmed
`actions, while signaling with status lights to keep the driver
`informed.
`
`SAFETY — To enhance the roof structure, a Spelts Car
`Club of America approved roll-bar was purchased and
`installed in the vehicle. Obviously, the structure of the roof
`itself in a production vehicle would be enhanced to meet the
`additional weight demands.
`In the event of fire, a halon fire suppression system was
`
`6
`
`

`

`installed. This system can provide a significant suppression
`of an electrical fire.
`
`The original power~assisted braking system was to
`remain intact to ensure proper braking. Since the engine was
`removed,
`the vacuum assist was disabled,
`therefore an
`electrically powered vacuum pump and reservoir were
`installed to replace this loss of vacuum.
`Additional safety devices include a panic switch that
`can be used to disconnect the battery pack from the vehicle
`in the event of emergency. An ill-line fuse and single-throw,
`double-pole circuit breaker were also installed to add
`additional redundancy for protection of the occupants and
`equipment. The circuit breaker also serves to isolate the
`batteries to allow for safe maintenance and testing of other
`components. Since a high voltage and current system is
`used, the chassis is not used as the ground as is the usual case
`in conventional vehicles. Both positive and negative cabling
`are used to minimize stray currents and voltages. and to
`isolate the system from the chassis. Additionally, circuit
`breakers, both 110V and 220V, have been installed between
`the on~board charger and the external power connections to
`ensure safe charger operation independent of the power
`source.
`
`CHARGING SYSTEM - A oat—board MOSFET battery
`charger was chosen for use in the vehicle. This charger is
`both lightweight and can accept. either 110 V or 220 V, 60
`Hz, AC power. To reduce weight, an isolation transformer is
`used as an off-board component.
`It was felt that future
`infrastructure eculd provide adequate
`isolation at
`the
`stationary charging connections.
`SUSPENSION — The large increase in vehicle weight
`due to the extra load of the KEV conversion required the
`suspension to be altered. The original springs did not provide
`adequate jounce. The conversion weight bias of 48% front
`weight/52% rear and accounting for the Iimit of 5% left/right
`bias from neutral resulted in the following added weight to
`ground per wheel from the original configuration:
`91 kg
`front. and 235 kg rear. Four new springs were purchased to
`meet
`these new loads. The damping coefficient of the
`MacPherson strut was not modified, hence the suspension
`characteristics have changed to a degree. However, after
`discussion with a strut manufacturer. the design team feels
`this change should not cause any significant problems.
`
`PERFORWNCE RESULTS
`
`The Alt/IPhibian has been tested on public roads and on
`a chassis dynamometer. Testing on public roads has included
`operation on highways, city streets, and rural roads. The
`terrain includes rolling hills in addition to level areas. The
`vehicle was driven on a modified FUDS cycle during testing
`on the dynamometer. General AMPhibian performance
`results are summarized in table 2.
`RANGE - During zero—emissions or ZEV mode the
`AMPhibian operates as a traditional electric vehicle. The
`vehicle has a range in ZEV mode of at least 70 km, and
`perhaps as high as 90 km, depending upon driving
`
`Table 2. Performance results for the U. S. Naval Academy's
`Hybrid Electric Vehicle.
`
`ZEV range:
`KEV range:
`Combined range:
`
`Acceleration,
`
`Oto70kph:
`Gradeability:
`ZEV Efficiency:
`HEV Efficiency:
`Total Range Efficiency:
`
`70-90 km
`740 km
`
`810-830 km
`
`<185
`> 6 %
`5.2 ktn/kW—h
`
`1.9 kmjkW—h 2.3 kmlikW—h
`
`conditions. Total ZEV range testing is incomplete. The
`Amnibian has been tested on a chassis dyntunometer in
`HEV mode with the APU operating continuously. Based
`upon data from this test, the vehicle has a projected range. in
`l-IEV mode, of ”MO km. Thus, the combined range between
`recharging or re—fueling of the AMPhibian is estimated to be
`810 km.
`ACCELERATION — The AMPhibian can achieve an
`
`acceleration from zero to 70 kph in less than 18 seconds
`when operating in either ZEV or HEV mode.
`This
`acceleration rate is somewhat lower than desired due to the
`
`the motor controller has ramp
`First,
`following reasons.
`circuitry that does not allow large rate changes in applied
`motor voltage. This means that when the accelerator pedal is
`pressed, the motor voltage will not immediately rise, but will
`ramp—up. Second,
`the motor controller is limited to 400
`amps or less depending upon controller temperature. These
`problems act to limit the peak torque and horsepower that
`can be developed in the DC motor. Finally, the stock Escort
`manual transmission is not ideally suited for the DC motor.
`The transmission exhibits a large gear ratio increase between
`first and second gears. This translates into a large load
`torque increase which the DC motor has difficulty in
`overcoming.
`the vehicle has been
`GRADEABILITY - Currently,
`evaluated on a 6% grade. This level of grade posed no
`serious problem and.
`in fact,
`the AMPhibian was able to
`accelerate from a stand-still even when started in second
`gear.
`
`EFFICIENCY - During ZEV testing the electriCal
`energy supplied by the batteries was measured found to be
`5.2 lon/kW-h. While operating in REV mode, the efficiency
`was
`found to be 1.9 lon/kW-h.
`The measured REV
`efficiency is Somewhat low as the APU stalled three times
`during the test and had to be operated with the choke on.
`This problem occurred due to a mechanical problem with the
`APU speed governor.
`
`A total combined efficiency can be found through a
`weighted average of the two operating modes where the
`weighting factor is the vehicle range while operating in each
`mode. This yields a total range combined average of 2.3
`
`7
`
`

`

`the conversion is not yet a cost effective
`about $10,000,
`alternative to existing gasoline vehicles. However,
`the
`potential reduction of smog in urban areas will continue to
`dictate the use of these vehicles.
`Future vehicle enhancements include the addition of small
`
`alternators to be used in conjunction to the existing brake
`system, to provide regeneration. Simulations provided by
`other authorsWchzalek, 1992) have shown potential energy
`savings
`from 6 to 20%, depending upon the driving
`conditions. Additionally, a significant effort is underway to
`both determine and implement a‘better control strategy.
`Further, the mechanical speed control of the APU engine
`may be replaced with an electronic control to help prevent
`engine stalls under heavy acceleration with significantly
`discharged batteries.
`The development of this vehicle has proven to be a valuable
`lesson in engineering design for both the midshipmen and the
`faculty of the U. S. Naval Academy. The team is currently
`working on design modifications
`and refinements
`in
`anticipation
`of
`the Second Hybrid Electric Vehicle
`Challenge, co-sponsored by Saturn Motors Corp, SAE
`International, and the Department of Energy. This event is
`scheduled to be held during June of 1994.
`
`REFERENCES
`
`Wyczalek, F. A., and Wang, T. C., SAE Tech. Paper, 1992,
`920648.
`
`Johnson Controls, Inc., Specialty Battery Division, Form
`number 41-6416(rev 5/92).
`
`ltm/kW—h. Obviously, the combined efficiency will vary
`significantly depending upon the operating strategy used
`when the vehicle is operated on a daily basis since the typical
`distance between recharging/refueling will be significantly
`less than the total combined range of 810 km. For example,
`the vehicle could be operated solely in ZEV mode if the
`typical distance between re—charging was less than about 70
`km. This would provide an effective efficiency that is much
`higher than a vehicle which is operated for long distances.
`EMISSIONS - The AMPhibian
`emissions were
`
`measured during the modified FUDS test in I—IEV mode with
`the APU on. These results are presented in table 3. To help
`minimize the emissions, a three-way catalytic converter is
`installed
`near
`the
`exhaust manifold
`of
`the APU.
`
`fresh air is inducted into the exhaust just
`Additionally,
`upstream of the converter to aid in the oxidizing process.
`Unfortunately, due primarily to the stalling problems which
`occurred during the emissions test as mentioned previously,
`the AMPhibian did not meet
`the TLEV standards.
`The
`
`carbon monOxide emissions were approximately ten times
`over the standard. This is due to the engine stalling problems
`as well as the resultant operation while under choke. The
`rich air-fuel mixture would naturally produce higher levels of
`carbon monoxide due to incomplete combustion.
`The
`mechanical problem with the speed governor has been fixed;
`however additional control work is required to prevent
`engine stalls under heavy loads when the propulsion batteries
`are significantly discharged. Further, a larger air-pump is
`being considered for fresh air induction to the converter.
`
`SUMMARY
`
`The design of a feasible hybrid electric vehicle for use
`in near-term applications has been presented. Continued
`testing and evaluation will
`reveal
`the
`reliability and
`durability of the various system components. However, the
`chosen batteries are expected to only maintain peak
`performance, under normal daily use, for 18 to 24 months
`before requiring replacement at an approximate cost of
`$1500. This cost is offset somewhat by the slightly reduced
`operating expenses due to the reduced use of gasoline,
`assuming electric power discounts for charging. Another
`costly system component is the lightweight alternator used in
`the APU. This item cost about $5000. The cost of this
`component would be greatly reduced if it were mass-
`produced. The total cost of components( less safety items
`and including a credit for the stock engine) came to about
`$14,000. So the cost of the alternator is a major portion of
`the total cost. Obviously, since the standard Escort cost
`
`Table 3. U. S. Naval Academy l-EEV Emissions.
`
`Comment
`(gm/mi)
`NMOG
`C0
`
`NOx
`
`62
`
`8
`
`