Simplified pattern recognition wheel slide protection

• US 5,654,889 A
• Filed: 06/02/1995
• Issued: 08/05/1997
• Est. Priority Date: 06/02/1995
• Status: Expired due to Term

• Current Assignee: Westinghouse Air Brake Technologies Corporation
• Original Assignee: Westinghouse Air Brake Technologies Corporation
• Inventors: Wood, James A., Greer, David A.
• Primary Examiner(s): Chin, Gary
• Application Number:
  US08/460,200
• Time in Patent Office: 795 Days
• Field of Search: 364/426.01, 364/426.015, 364/426.027, 180/197, 246/168.1, 303/95, 303/100, 303/103, 303/128
• US Class Current: 701/71
• CPC Class Codes: B60T 8/1705 for rail vehicles

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.

Claims

1. A wheel slip control system for modulating brake application forces being applied to a passenger transit type railway vehicle having a plurality of axles on which wheels are mounted, said wheel slip control system comprising:

(a) a first means disposed on said railway vehicle and connected to at least receive a set of first signals indicative of a speed for each of said axles and a set of second signals indicative of an acceleration rate for each of said axles for both processing said set of first signals and said set of second signals and for generating a set of third signals indicating, for each of said axles, when said wheels are slipping;

(b) a second means connected to receive at least said set of first signals indicative of said speed for each of said axles and said set of second signals indicative of said acceleration rate for each of said axles and said set of third signals indicating, for each of said axles, when said wheels are slipping for generating a set of fourth signals indicating an energy loss due to a wheel slip for each of said axles;

(c) a third means connected to receive at least said set of fourth signals indicating said energy loss due to said wheel slip for each of said axles for generating a set of fifth signals indicative of a wheel slip enable timeout value for each of said axles;

(d) a fourth means connected to receive at least said set of fifth signals indicative of said wheel slip enable timeout value for both generating a set of sixth signals indicative of a time of a wheel slip correction and for generating a set of seventh signals for ending a wheel slip correction when said time indicated by one of said set of sixth signals reaching said timeout value indicated by one of said set of fifth signals for each of said axles;

(e) a fifth means connected to receive at least said set of seventh signals for ending said wheel slip correction, said fifth means reapplying said brake application forces to said railway vehicle.

2. A wheel slip control system, according to claim 1, wherein said first means for processing said set of first signals indicative of said axle speeds and said set of second signals indicative of said acceleration rate and generating said set of third signals indicating said wheel slip for each axle of said railway vehicle further comprises:

(i) means for identifying a time when said railway vehicle is in motion, but when wheel slip is not occurring, and for generating a signal for normalization enable for said plurality of axles;

(ii) means connected to receive at least said signal for normalization enable and said set of first signals indicative of said axle speeds for generating a set of signals indicating normalization factors which are dependent upon relative wheel diameters based on said set of first signals indicative of said axle speeds;

(iii) means connected to receive at least said set of first signals and said set of signals indicating said normalization factors for generating a set of signals indicating normalized axle speeds;

(iv) means connected to receive at least said set of signals indicating said normalized axle speeds for generating a signal indicative of a highest normalized axle speed;

(v) means connected to receive at least said set of signals indicating said normalized axle speeds and said signal indicative of said highest normalized axle speed for generating a set of signals indicating slippage for each axle of said railway vehicle for any axle having a normalized axle speed which is less than said highest normalized axle speed.

3. A wheel slip control system, according to claim 1, further including a means for generating, for each axle, a signal which indicates that wheel slip has ceased based on a polarity shift in said acceleration rate indicated by one of said set of second signals.

4. A wheel slip control system, according to claim 3, wherein said means for determining that wheel slip has ceased uses as a criterion a shift in polarity from positive to negative of said acceleration rate indicated by one of said set of second signals.

5. A wheel slip control system, according to claim 1, wherein said means for processing said set of first signals indicative of said axle speeds and said set of second signals indicative of said acceleration rate and generating said signals indicating wheel slip further comprises:

(i) means for generating a set of signals indicative of rate polarity for each of said axles;

(ii) means for generating a set of signals representing detection of a positive rate polarity based on said set of signals indicative of said rate polarity for each one of said axles;

(iii) means for generating a set of signals, each representing detection of a polarity shift which indicates a change in said acceleration rate of one of said axles from positive to negative;

(iv) means for using said set of signals indicative of said detection of polarity shift for generating a set of signals for termination of said wheel slip correction.

6. A wheel slip control system, according to claim 1, wherein said railway vehicle has a plurality of trucks on which said axles are mounted and wherein said wheel slip control system further comprises:

(i) means connected to receive at least said set of first signals indicative of said axle speed and said set of second signals indicative of said acceleration rate for generating a set of signals indicative of wheel slip intensity, one for each axle of said railway, vehicle;

(ii) means connected to receive and convert said set of signals indicative of wheel slip intensity for generating a said set of signals indicative of priority for each said axle of said railway vehicle;

(iii) means for comparing each one of said set of signals indicative of priority for each of said axles on a truck and applying brake force reduction dependent upon a highest one of said priorities indicated by said said set of signals indicative of priority for each of said axles on said truck.

7. A wheel slip control system for modulating brake application forces on a passenger transit type railway vehicle having a plurality of axles on which wheels are mounted, said wheel slip control system comprising:

(a) a first means disposed on said railway vehicle and connected to receive at least a set of first signals indicative of a speed for each of said axles and a set of second signals indicative of an acceleration rate for each of said axles for both identifying a time when wheel slip is not occurring and for generating a third signal for normalization enable when said wheel slip is not occurring;

(b) a second means connected to receive said set of first signals indicative of said speed for each of said axles and said third signal for said normalization enable for generating a set of fourth signals indicative of normalization factors which are dependent upon relative wheel diameter calculated from relative axle velocities for each of said axles on said railway vehicle during said time when said third signal for said normalization enable indicates that said wheel slip is not occurring;

(c) a third means connected to receive said set of first signals indicative of axle speeds and said set of fourth signals indicative of said normalization factors for generating a set of fifth signals indicative of normalized axle speeds for each of said axles;

(d) a fourth means connected to receive said set of second signals indicative of said acceleration rate and said set of fifth signals indicative of said normalized axle speeds for generating a sixth signal for brake valve control based on said set of second signals indicative of said acceleration rate and said set of fifth signals indicative of said normalized axle speed for each of said axles; and

(e) a fifth means for processing said sixth signal for said brake valve control through a series of tests based on at least said set of second signals indicative of said acceleration rate and said set of fifth signals indicative of said normalized axle speed, to produce a seventh signal for brake valve control having at least five values, one for full brake application, one for generating a pulsed brake application signal, one for holding brakes, one for generating a pulsed brake release signal and one for releasing brakes; and

(f) means for processing said set of second signals indicative of said acceleration rate and said set of fifth signals indicative of said normalized axle speed for each of said axles to generate a signal indicative of a priority for brake force reduction and processing said priority signal to generate a signal for a duration of the pulsed brake release signal and a signal indicative of a waiting time between the pulsed brake release signals.

8. A wheel slip control system, according to claim 7, wherein said means for producing said seventh signal for brake valve control further comprises:

(i) means for processing said set of second signals indicative of said axle acceleration rate to obtain a signal indicative of a rate of change in time of said axle acceleration rate;

(ii) means for processing said set of second signals indicative of said axle acceleration rate to obtain a signal indicative of an-acceleration rate in excess of a predetermined value;

(iii) means for processing said set of fourth signals indicative of said normalized axle speeds to obtain a signal for indicating a lower band to said axle acceleration rate;

(iv) means for processing each one of said second signals indicative of said axle acceleration rate and said signal indicating said lower band to obtain a said indicative of an acceleration rate less than said lower band; and

(v) means for using said signal indicative of a rate of change in time of said axle acceleration rate, said signal indicative of an acceleration rate in excess of a predetermined value, and said signal indicative of an acceleration rate less than said lower band in said series of tests.

9. A process for modulating brake application forces to control wheel slip on a passenger transit type railway vehicle having a plurality of axles on which wheels are mounted, said process comprising the steps of:

(a) receiving a set of first signals indicative of a speed for each of said axles and a set of second signals indicative of an acceleration rate for each of said axles and processing said set of first signals and said said set of second signals and generating a set of third signals indicating, for each of said axles, when said wheels are slipping;

(b) processing at least said set of first signals indicative of said speed for each of said axles, said set of second signals indicative of said acceleration rate for each of said axles and said set of third signals indicating, for each of said axles, when said wheels are slipping, to generate a set of fourth signals indicating an energy loss due to said wheel slip for each of said axles;

(c) processing said set of fourth signals indicating said energy loss due to said wheel slip for each of said axles to generate a set of fifth signals indicative of a wheel slip enable timeout value for each of said axles;

(d) processing said set of fifth signals indicative of said wheel slip enable timeout value to generate a set of sixth signals indicative of a time of a wheel slip correction and a set of seventh signals for ending said wheel slip correction when said time indicated by one of said set of sixth signals reaching said timeout value indicated by one of said set of fifth signals, for each of said axles; and

(e) processing at least said set of seventh signals for ending said wheel slip correction to reapply said brake application forces.

10. A wheel slip control process, according to claim 9, wherein said step of processing said set of first signals indicative of said axle speeds and said set of second signals indicative of said acceleration rate and generating said third signal indicating said wheel slip for each of said axles of said railway vehicle further comprises the additional steps of:

(i) identifying a time when said railway vehicle is in motion, but when said wheel slip is not occurring and generating a signal for normalization enable for said plurality of said axles;

(ii) processing said set of first signals indicative of said axle speeds to, generate a set of signals relative wheel diameters, said processing being activated by said signal for said normalization enable;

(iii) processing said set of first signals indicative of said axle speeds and said set of signals indicating said normalization factors to generate a set of signals indicating normalized axle speeds;

(iv) processing said set of signals indicating said normalized axle speeds to generate a signal indicative of a highest normalized axle speed; and

(v) processing said set of signals indicating said normalized axle speeds and said signal indicative of said highest normalized axle speed to generate a signal for each of said axles of said railway vehicle, said signal indicating slippage for any axle having a normalized axle speed less than said highest normalized axle speed.

11. A wheel slip control process, according to claim 9, further including the step of generating for each of said axles a signal for indicating that said wheel slip has ceased based on a polarity shift in said acceleration rate indicated by one of said set of second signals.

12. A wheel slip control process, according to claim 11, wherein said step of determining that said wheel slip has ceased uses as a criterion a shift in polarity from positive to negative of said acceleration rate indicated by said one of said set of second signals.

13. A wheel slip control process, according to claim 9, wherein said step of processing said set of first signals indicative of said axle speeds and said set of second signals indicative of said acceleration rate and generating said third signals indicating said wheel slip further comprises the steps

(i) generating a signal indicative of a rate polarity for each of said axles;

(ii) generating a signal for representing detection of a positive rate polarity based on said signal indicative of said rate polarity for each of said axles;

(iii) generating a signal for representing detection of a polarity shift which indicates a change in said acceleration rate from positive to negative; and

(iv) using said signal indicative of said detection of said polarity shift to generate a signal for terminating said wheel slip correction.

14. A wheel slip control process, according to claim 9, wherein said railway vehicle has a plurality of trucks on which said axles are mounted, and wherein said wheel slip control process further comprises the steps of:

(i) processing said set of first signals indicative of said axle speed and said set of second signals indicative of said acceleration rate to generate a said set of signals indicative of wheel slip intensity for each of said axles of said railway vehicle;

(ii) processing said said set of signals indicative of said wheel slip intensity to generate a said set of signals indicative of a priority for each of said axles of said railway vehicle; and

(iii) comparing said said set of signals indicative of said priority for each of said axles on a truck and applying a brake force reduction which is dependent upon a highest one of the priorities for all of said axles on said truck.

15. A wheel slip control process comprising the following steps:

(a) processing at least a set of first signals indicative of a speed for each of said axles and a set of second signals indicative of an acceleration rate for each of said axles to identify a time when wheel slip is not occurring and generating a third signal for normalization enable when said wheel slip is not occurring;

(b) processing said set of first signals indicative of said speed, and said third signal for said normalization enable to generate a set of fourth signals indicative of normalization factors which are dependent upon relative wheel diameter based on relative axle velocities for each of said axles on said railway vehicle during said time when said third signal for said normalization enable indicates that said wheel slip is not occurring;

(c) processing said set of first signals indicative of said axle speeds and said set of fourth signal, indicative of said normalization factors to generate a set of fifth signals indicative of normalized axle speeds for each of said axles;

(d) processing said set of second signals indicative of said acceleration rate for each of said axles and said set of fifth signals indicative of said normalized axle speeds to generate a set of sixth signals for brake valve control for each of said axles; and

(e) processing said set of sixth signals for said brake valve control through a series of tests based on at least said set of second signal, indicative of said acceleration rate for each of said axles and said fourth signal indicative of said normalized axle speed to produce a seventh signal for brake valve control having at least five values, one for full brake application, one for generating a pulsed brake application signal, one for holding brakes, one for generating a pulsed brake release signal, and one for releasing brakes;

(f) processing said set of second signals indicative of said acceleration rate for each of said axles and said set of fifth signals indicative of said normalized axle speed for each of said axles to generate a signal indicative of a priority for brake force reduction, a signal indicative of a duration of the pulsed brake release signal and a signal indicative of a waiting time between the pulsed brake release signals.

16. A wheel slip control process, according to claim 15, wherein said step of processing said set of sixth signals for brake valve control of an axle further comprises the steps of:

(i) processing one of said second signals indicative of said axle acceleration rate to obtain a signal indicative of a rate of change in time of acceleration;

(ii) processing said second one signal indicative of said axle acceleration rate to obtain a signal indicative of acceleration in excess of a predetermined value;

(iii) processing one of said set of fourth signals indicative of said normalized axle speed to obtain a signal for indicating a lower band to said axle acceleration rate;

(iv) processing said one second signal indicative of said axle acceleration rate and said signal indicating said lower band to obtain a signal indicative of an acceleration rate less than said lower band; and

(v) using said signal indicative of a rate of change in time of said axle acceleration rate, said signal indicative of acceleration in excess of a predetermined value, and said signal indicative of acceleration rate less than said lower band in said series of tests to produce said seventh signal.