Patent GB-1156538-A (GB)
Title: Vehicle Speed Control Apparatus
IPC: B61L3/00
Filed: 1966-09-30
Abstract: 1,156,538. Automatic train control. WESTINGHOUSE AIR BRAKE CO. 30 Sept., 1966 [1 Oct., 1965 (3)], No. 43792/66. Heading B7N. [Also in Division H2] An induction motor 38 which drives a train 11 has its pole-number and/or frequency controlled by signals from a wayside transmitter 16 whose frequency indicates the maximum speed at which the train may travel. The transmitter is coupled through coils 19, 14, with a track circuit associated with pick-up coils 39, 40 connected through filter 51 with a split phase motor 52, the speed of which is proportional to the frequency of the signals. When a signal is detected, relay D connects power supply 37 to pole selector 36, and the vehicle brakes are released. The motor 52 drives centrifugal mechanism 56 for moving switch-arm 59 and energizing relays A, B, C, in sequence as the speed increases. When relay A is de-energized, the source 37 is connected to terminals 1, 2, 3 of windings 41 on the traction motor 38, the terminals 4, 5, 6 being inter-connected, thus providing a 16-pole connection. Actuation of relay A connects the power supply to the terminals 4, 5, 6 of the winding 41 to provide an 8-pole connection. Winding 42 similarly provides 4-pole and 2-pole operation in response to the selective actuation of relays B and C over the higher speed ranges. Interruption of the signals from the transmitter 16 disconnects the traction motor and applies the brakes. In another arrangement, an alternator is driven at a speed proportional to the frequency of the control signals to regulate the rate of commutation of inverters in circuit with the traction motor, the inverters being connected to a D.C. source. Each inverter comprises a pair of silicon controlled rectifiers which are triggered alternately by pulses from the alternator to energize a centre-tapped transformer winding coupled with a winding on the traction motor. Each controlled rectifier is quenched by a capacitor-choke network, Fig. 6 (not shown). In a further embodiment, a pair of alternators having different pole-numbers are connected to a frequency selector which operates in response to train speed to connect one or other of the alternators to the inverters. The polenumber of the traction motor is also varied in response to the speed of the vehicle, Fig. 7 (not shown). Thus, over an initial speed range, an 8-pole connection for the motor and a 4-pole alternator-connection is used. When the train reaches a predetermined speed, a 2-pole alternator arrangement and a 4-pole alternator arrangement and a 4-pole motor-connection obtains. Another arrangement relates to a modification in which four alternators having different pole-numbers are driven at a speed proportional to the frequency of the control signal, a centrifugal selector switch for determining the pole number being driven by the same means. A frequency-responsive brake and power control arrangement is connected between the inverters and pole-changer, Fig. 10 (not shown). Thus, the alternator arrangement is changed stepwise from a 16-pole to a 2-pole connection as the frequency output of the transmitter 16 increases, whilst the motor is changed between high and low pole-number. A comparator indicates the actual and desired speeds of the train.