Appeal No. 2003-0275 Page 7
Application No. 09/550,032
solenoid valves 102 and 104, actuators 114 and 116, and electric rear brakes 48 and
50.
The motor drive unit 18 may be a single drive motor driving both wheels 24 and
26, may be two motors connected back-to-back driving wheels 24 and 26, or may be
two or more motors with each motor incorporated into each wheel assembly.
Additionally, the motors may be AC motors or DC motors, including one or more
brushless DC motors. The drive train preferably comprises a reduction gear set
coupled to the motor output shaft and driving the vehicle drive wheels.
Bodie operating condition 2 (column 4, lines 16-64) teaches the following:
Assume that accelerator pedal 20 is not depressed and that brake pedal
70 is depressed. When brake pedal 70 is depressed, master cylinder 78
provides hydraulic pressure in hydraulic lines 86 and 87 proportional to the
amount of pressure placed on the brake pedal by the foot of the vehicle operator.
A brake switch 72 provides a signal through line 76 to brake controller 66
indicating that brake pedal 70 has been depressed. In response to the signal
indicating that brake pedal 70 has been depressed, solenoid valves 102 and 104
are commanded via line 120 to close, isolating hydraulic lines 94 and 96 from
hydraulic lines 40 and 42. The pressure signals on lines 84 and 85 from pressure
transducers 88 and 90 indicate the amount of pressure in hydraulic lines 86 and
87, which is a measure of the pressure applied to the brake pedal 70.
Accumulator 92 has two expandable chambers that expand when fluid
pressure on pistons 93 forces center spring 91 to compress. This allows the
brake pedal to be depressed in a normal manner when more pressure is applied
to the brake pedal, despite the closing of solenoid valves 102 and 104. Without
accumulator 92, when solenoid valves 102 and 104 close, travel of the brake
pedal 70 would be substantially halted.
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Last modified: November 3, 2007