Acceleration control system for electrically propelled traction vehicles

Claim 2

In a control system for propulsion motors of a vehicle wherein a first signal representative of a sensed motor parameter which is a function of motor torque, such as motor current, and a control signal representative of desired vehicle acceleration are applied to the inputs of comparison means whose output actuates switching means controlling the propulsion motor circuit so as to maintain desired vehicle acceleration, the combination comprising: a. a source of said first signal whose magnitude is directly proportional to propulsion motor current; b. a source of said control signal; c. a resistance network comprising a potentiometer having a potentiometer arm; d. means for automatically maintaining the setting of said potentiometer arm proportional to the actual loaded weight of said vehicle; e. means for coupling said first signal through said resistance network to one of the inputs of said comparison means such that the signal applied to said one input has a magnitude proportional to the magnitude of the first signal divided by the actual loaded weight of the vehicle and for coupling said control signal directly to another input of said comparison means, so that the first and control signals upon comparison are ratioed in respect to each other proportionately to the actual loaded weight of the vehicle.

Claim 3

The arrangement of claim 1 wherein said resistance network comprises said potentiometer and additional resistance means coupled serially to said source of first signals, said potentiometer arm being connected to one end terminal of the potentiometer such that the total resistance of said potentiometer varies proportionately with vehicle weight, and means to couple the signal appearing across said additional resistance means to said one input of said comparison means.

Claim 4

The arrangement of claim 2 wherein the signal coupled to said one input equals:

Claim 5

The arrangement of claim 1 comprising means to offset one of said signals by a fixed voltage magnitude representative of propulsion motor and windage and friction losses.

Claim 6

In a control system for vehicles wherein impedance means in circuit with electrical propulsion motors are sequentially commutated in a predetermined sequence, the combination comprising: a. a source of first signals responsive solely to propulsion motor current; b. a source of reference signals representative of desired propulsion motor acceleration; c. comparison means having a plurality of inputs and at least one output; d. a resistance network comprising a potentiometer having a potentiometer arm; e. means for automatically maintaining the setting of said potentiometer arm proportional to the actual loadeD weight of the vehicle; f. means for coupling said first signals through said resistance network to one of the inputs of said comparison circuit such that their magnitude is modified proportionately to the actual weight of the vehicle, whereby the signals applied to said one input are proportional to vehicle acceleration, and for coupling said reference signals to another input of said comparison circuit so that the first and reference signals upon comparison are ratioed in respect to one another proportionally to the actual loaded weight of the vehicle; g. commutation control means; h. means for coupling the output of said comparison means to said commutation control means to automatically control the time interval between successive commutations to provide vehicle acceleration in accordance to said reference signal.

Claim 7

In a control system for vehicles wherein impedance means in circuit with electrical propulsion motors are sequentially commutated in a predetermined sequence, the combination comprising: a. a source of first signals responsive solely to propulsion motor current; b. a source of reference signals representative of desired propulsion motor acceleration; c. comparison means having a plurality of inputs and at least one output; d. a resistance network comprising a potentiometer having a potentiometer arm; e. means for automatically maintaining the setting of said potentiometer arm proportional to the actual loadeD weight of the vehicle; f. means for coupling said first signals through said resistance network to one of the inputs of said comparison circuit such that their magnitude is modified proportionately to the actual weight of the vehicle, whereby the signals applied to said one input are proportional to vehicle acceleration, and for coupling said reference signals to another input of said comparison circuit so that the first and reference signals upon comparison are ratioed in respect to one another proportionally to the actual loaded weight of the vehicle; g. commutation control means; h. means for coupling the output of said comparison means to said commutation control means to automatically control the time interval between successive commutations to provide vehicle acceleration in accordance to said reference signal.

Claim 8

The arrangement of claim 5 wherein said comparison means comprises bi-level switching means providing an output whose level is switched from a first to a second state dependent on the relative magnitudes of said first and reference signals, the level of said first state permitting further commutation and the level of said second state inhibiting further commutation.

Claim 9

The arrangement of claim 6 comprising an acceleration control circuit responsive to the acceleration signals and arranged to provide an additional bi-level output to said commutation control means, said additional output having a first level permitting further commutation during time intervals when the rate of change of acceleration is within a predetermined level and a second level inhibiting further commutation when the rate of change of acceleration is in excess of a predetermined level.

Claim 10

The arrangement of claim 7 wherein said acceleration control circuit comprises a clamped ramp circuit responsive to a rapid change in the level of said acceleration signal to produce a ramp signal whose level changes at a predetermined slow rate and means for comparing said acceleration signal and said ramp signal to produce an output signal having a level inhibiting commutation from the commencement of said rapid change until the level of said ramp signal substantially equals the instantaneous level of said acceleration signal.

Claim 11

An automatic acceleration control for traction vehicles wherein a multiple contact controller is driven by an electrical pilot motor means to rotate the controller cam shaft to successive index positions to incrementally commutate resistances connected in circuit with the electrical traction motor, pilot motor circuit means for said pilot motor; the combination for sequentially gating said pilot motor circuit to control the acceleration of said vehicle, comprising: a. a source of current signals whose magnitude is directly proportional to traction motor armature current; b. means for converting said current signals to a first voltage signal substantially proportional to traction motor torque; c. means responsive to actual vehicle weight for dividing said first voltage signal by a proportionality factor representative of actual traction vehicle weight to derive an acceleration voltage representative of actual traction vehicle acceleration; d. means for comparing said acceleration voltage and said reference voltage to produce a first output to said pilot motor circuit means permitting actuation of said pilot motor means and commutation of said resistances when the acceleration voltage is below the acceleration level commanded by said reference voltage, and to produce a second output inhibiting actuation of said pilot motor means when the acceleration voltage attains the level of said reference voltage.

Claim 12

An automatic acceleration control for traction vehicles wherein a multiple contact controller is driven by an electrical pilot motor means to rotate the controller cam shaft to successive index positions to incrementally commutate resistances connected in circuit with the electrical traction motor, pilot motor circuit means for said pilot motor; the combination for sequentially gating said pilot motor circuit to control the acceleration of said vehicle, comprising: a. a source of current signals whose magnitude is directly proportional to traction motor armature current; b. means for converting said current signals to a first voltage signal substantially proportional to traction motor torque; c. means responsive to actual vehicle weight for dividing said first voltage signal by a proportionality factor representative of actual traction vehicle weight to derive an acceleration voltage representative of actual traction vehicle acceleration; d. means for comparing said acceleration voltage and said reference voltage to produce a first output to said pilot motor circuit means permitting actuation of said pilot motor means and commutation of said resistances when the acceleration voltage is below the acceleration level commanded by said reference voltage, and to produce a second output inhibiting actuation of said pilot motor means when the acceleration voltage attains the level of said reference voltage.

Claim 13

The arrangement of claim 9 comprising backup means for comparing said acceleration voltage and said reference voltage to actuate means to reverse the normal direction of said pilot motor means during vehicle retardation in the event the level of said reference signal is below the level of said acceleration voltage and To permit commutation until vehicle deceleration is decreased to the level commanded by said reference signal.