Operating system for electrically driven vehicles

Claim 1

An operating system for an electrically driven vehicle of the type wherein power is fed from a DC source to an electric motor, via a chopper circuit, the system comprising: a a relay having an armature and at least one pair of normally open contacts, said contacts being serially connected with said motor, for applying said DC source to said motor; b switching means, serially connected with the armature winding of said relay, the series circuit so formed being connected in parallel with said motor, said switching means including an accelerator switch coupled to the accelerator pedal of said vehicle; c a variable-resistance transducer coupled to said accelerator pedal; d a signal generator, controlled by said variable-resistance transducer, for generating a gating signal for said chopper circuit, in accordance with the instantaneous position of said accelerator pedal; e. control circuit means having at least two inputs and an output, said output being connected to said switching means to render same conductive if the signals present on said inputs indicate normal operation of said chopper circuit and said variable-resistance transducer; f. an auxiliary resistor connected between said variableresistance transducer and one side of said DC source, the voltage which is developed across said auxiliary resistor being connected to one of the inputs of said control circuit, the other input thereof being connected to that side of said chopper circuit which connects to said motor; and g. means, connected to said switching means, and activated by a drop in the voltage developed across said chopper circuit, for disabling said switching means in the event that a fault occurs in said chopper circuit or said transducer, after said control circuit has rendered said switching means conductive.