초록 ▼

The electric vehicle driven by a DC motor having a field winding. An electric resistance element can be switched into parallel circuit with the field winding to weaken the field and increase potential motor speed. A relay operates the switch, a Hall-effect switch responsive to motor rotation produce

The electric vehicle driven by a DC motor having a field winding. An electric resistance element can be switched into parallel circuit with the field winding to weaken the field and increase potential motor speed. A relay operates the switch, a Hall-effect switch responsive to motor rotation produces voltage pulses indicative of motor speed. A microcomputer counts pulses in a given time period to determine motor speed and compares the speed with that in the prior period to determine whether the motor speed is increasing or decreasing. The computer is programmed to operate the relay to close the switch as the motor speed increases above a first speed and to open the switch as motor speed subsequently decreases to a second speed lower than said first speed. The computer is programmed to respond to a third speed greater than the first speed to operate the relay to open said switch to prevent overspeed. The computer also responds to a fourth speed lower than the third speed and greater than the first speed to operate the relay to close the switch means subsequent to opening said switch at the third speed, thus restoring field weakening after the overspeed has been corrected.

대표청구항 ▼

An electric vehicle driven by a DC motor, said vehicle having a field winding, an electric resistance element in circuit with said field winding, a switch in said circuit operative when closed to place said element in parallel with said field winding to weaken the field and increase potential motor

An electric vehicle driven by a DC motor, said vehicle having a field winding, an electric resistance element in circuit with said field winding, a switch in said circuit operative when closed to place said element in parallel with said field winding to weaken the field and increase potential motor speed, relay means for operating said switch, means to determine motor speed, computer means for determining whether the motor speed is increasing or decreasing, and means for operating said relay means to close said switch at a first speed but only if said motor speed is increasing and to actuate said switch at a second speed lower than said first speed but only if said switch has been closed previously and motor speed is decreasing.