Appeal No. 2004-0058
Application No. 09/728,518
Field's electric hybrid automobile has three operating modes; urban mode,
highway mode and engine mode. The manner of operation is described by Field
(column 5, line 45, to column 8, line 31) as follows:
URBAN MODE
Urban mode uses a straight electric drive in which the batteries 24 power
the electric motor 22 which drives the automobile, and the combustion engine 28
is not running. Urban mode is used to start the car from a standstill and get it up
to highway speed. It is also useful for around town stop-and-go service. Driving is
done conventionally. The driver first turns on master switch 78, which powers up
the electric hybrid system. He or she then places the car in gear, using gear shift
lever 18, foot operated clutch 20 and 4-speed transmission 16. There is a
conventional foot accelerator pedal connected to accelerator potentiometer 80.
Depressing the pedal directs a variable voltage from zero to 10 volts from the
accelerator potentiometer 80 through the process controller 52 to the motor
controller 60. The more the pedal is depressed the higher the voltage will be up
to the 10-volt limit. This variable voltage causes motor controller 60 to feed a
proportionate supply of current to electric motor 22 so that the car moves
smoothly at a speed commanded by the driver. Forward and reverse are
obtained in conventional automotive manner by shifting gears in transmission 16.
When the car is moving and the driver takes his or her foot off the accelerator
pedal the motor controller 60 will stop feeding current to motor 22. The still
spinning motor will act like a generator and feed current back to the batteries 24,
consuming some kinetic energy in so doing, which will tend to slow down the car.
This so-called regenerative braking is well known. A flywheel 26 is attached to
the shaft of motor 22 to maintains its angular momentum so it will not slow down
too abruptly due to this dynamic braking.
Urban mode provides a convenient, virtually silent and essentially
pollution free manner of operation. However, the range of the automobile will be
limited by the capacity of the batteries 24. For cross country operation a greater
range is needed, and this may be obtained by operating in highway mode or
engine mode. Highway mode will be discussed next.
HIGHWAY MODE
After the car has been started in urban mode and brought up to some
speed, for example 1000 RPM on the electric motor 22, the driver may elect to
enter highway mode. This is done by pushing the "highway mode" button 82 on
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