Appeal No. 2004-0058
Application No. 09/728,518
After the combustion engine is running, the process controller 52 will read
the speeds of the electric motor and the combustion engine from speed monitors
54 and 56 and adjust the engine speed with servo speed control 50 until the two
speeds are equal. The process controller will then engage electric clutch 30,
thereby coupling engine 28 mechanically to electric motor 22. The signal from
accelerator potentiometer 80 will then be shifted to servo speed control 50 so
that the driver can control the speed of the automobile by controlling the speed
of engine 28. He or she may then continue to drive normally. Engine 28 will be
powering the car.
In this condition there will be no signal from process controller 52 to motor
controller 60, but motor 22 will be spinning, so motor controller 60 will call for
regenerative braking. Motor 22 will act as a generator and supply current to the
batteries 24. The rate of current flow will depend on the speed of the motor and
the charge level of the batteries. This should be taken into account when setting
the charge level at which the combustion engine is to be brought on line. A
charge level of 70% seems to be suitable, but another level might be preferred.
Therefore in this condition engine 28 not only powers the car but also
recharges the batteries 24. Every 5 minutes, or other selected time interval, the
process controller will read the charge level of the batteries. When they are
essentially fully charged, for example at 95% charge level, the process controller
will disengage electric clutch 30 and stop engine 28 by closing solenoid fuel
valve 48 or operating other suitable control means. Alternatively, the engine may
be idled rather than stopped. The signal from the accelerator potentiometer 80
will be shifted from servo speed control 50 to motor controller 60 and operation
of the car will revert to fully electric.
This alternating sequence of operating on the batteries until they are
partially discharged, then operating on the combustion engine until the batteries
are charged up, then back to the batteries, will continue as long as the driver
keeps the car in highway mode. It is a very efficient mode of operation. It runs
the combustion engine near its rated power and hence near its maximum
efficiency for part of the time, then shuts it off to save fuel and uses electric
power. However, the batteries are never deeply depleted, so there is always
good battery capacity available for urban mode operation when needed. Range
is limited only by the fuel consumption of the engine 28 and the size of the fuel
tank 46. As with a conventional car, periodically refilling the fuel tank will extend
the range.
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