Simplified pattern recognition wheel slide protection

Abstract

This invention provides method and apparatus for an improved pattern recognition wheel slide protection system for passenger transit type railway vehicles. It receives as inputs the rotational velocities of all the axles on the vehicle, and the acceleration rates for the axles. It also receives signals for brake cylinder pressure. The system uses the velocity and acceleration data to determine whether the wheels on an axle are slipping, and determines the severity of the slip. It calculates a timeout value based on the severity of the slip, and times a slip correction until the timeout value is reached, whereupon the slip correction is terminated. The system uses a simplified logic for providing brake control signals. A cascade logic method is used in which the brake control signal starts out indicating full application, then, based on signals indicating change in sign of acceleration rate, and acceleration rate in excess of a predetermined value, changes the brake control signal to pulsed brake application. Further indications based on axle velocity and acceleration cause the signal to change to a hold signal, then to a release pulse signal, and finally to a signal for release. This cascaded logic provides signals for brake valve control which have five values, APPLY, APPLY PULSE, HOLD, RELEASE PULSE, and RELEASE. Information obtained from axle rate signals is also used to specify for the RELEASE PULSE mode the duration of release and the duration of hold.