RELATIVE SPEED CONTROL SYSTEM FOR DC MOTOR VEHICLE DRIVE

• US 3,760,246 A
• Filed: 06/28/1971
• Issued: 09/18/1973
• Est. Priority Date: 02/25/1969
• Status: Expired due to Term

• Current Assignee: David Gurwicz, Edwin Amitage Battye, James Wright
• Original Assignee: David Gurwicz, Edwin Amitage Battye, James Wright
• Inventors: Gurwicz, David, Battye, Edwin Amitage, Wright, James
• Primary Examiner(s): Rubinson, Gene Z.
• Application Number:
  US05/157,416
• Time in Patent Office: 813 Days
• Field of Search: 318/52,98-100
• US Class Current: 318/52
• CPC Class Codes: B60L 15/2036 Electric differentials, e.g. for supporting steering vehicles
• CPC Class Codes: H02P 5/685 electrically connected in series, i.e. carrying the same current
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A control system for two DC motors driving the driving wheels of an electric vehicle. Sensing means detect a differential speed between the two motors and act to remove the voltage to the faster motor, to eliminate the speed differential, and simultaneously reduce the voltage to the other motor. Override means are preferably provided to enable the system to be bypassed when the vehicle is turning to allow the outer wheel to revolve faster than the inner wheel.

Claims

1. A control system for two direct current electric motors having at least their armatures connected in series, comprising sensing means adapted to detect the occurence of an excessive speed differential between said motors, means for removing the voltage applied to the faster motor to eliminate the excessive speed differential, voltage reducing means being provided for reducing the effective voltage applied to the other motor to a safe value.

2. A control system according to claim 1, in which means are provided and adapted, upon sensing of said speed differential, to open-circuit the armature of said faster-running motor and to provide an alternative current path to the other motor, whereby the back e.m.f. of the faster-running motor is reduced.

3. A control circuit according to claim 2, in which said means comprises, in each armature circuit a two position switch controlled by a relay, actuation of the relay causing a change in position of the switch to open circuit the armature and complete the alternative current path.

4. A control system according to claim 1 in which said voltage reducing means comprises an electronic system utilizing semi-conductors and said electronic system comprises an SCR chopper fed by a pulse generator which determines the mark to space ratio of the chopper and the pulse generator being fed through a potentiometer in sines with a resistor which is normally short circuited, the short circuit being removed when the voltage is removed from either motor thereby to reduce the input voltage to the pulSe generator and the output of the SCR chopper.

5. A control system according to claim 1 in which means are provided to prevent an undesirable frequency of operation of the system.

6. A control system according to claim 1, in which said sensing means includes a tacho-generator attached to each armature.

7. A control system as in claim 1 wherein said two direct current electric motors are operative to drive the driving wheels of an electric vehicle, and including override means adapted to deactivate the control system when the vehicle is turning in a tight circle to allow a speed differential between the wheels for turning purposes, said override means comprising microswitches operated by corresponding cams on each driving wheel when the corresponding wheel has turned through a certain predetermined angle, and relays controlled by the microswitches so that on actuation of a microswitch the corresponding relay acts to prevent removal of voltage applied to the faster motor.

8. A control system as in claim 1 wherein said two direct current electric motors are operative to drive the driving wheels of an electric vehicle, and including override means adapted to de-energise the control system when the vehicle is turning in a tight circle to allow a speed differential between the wheels for turning purposes, the override means comprising means for preventing removal of voltage of the faster running motor and means for open or short circuiting the slower running motor.

9. An electrically driven vehicle comprising at least two driving wheels, two electric motors respectively in driving connection with the two driving wheels, said electric motors having at least their armatures connected in series, and a control system for said motors comprising sensing means adapted to detect the occurrence of an excessive speed differential between said motors, means for removing the voltage applied to the faster motor to eliminate the excessive speed differential, and voltage reducing means for reducing the effective voltage to the other motor to a safe value.