Predicting wheel slip and skid in a locomotive

• US 7,084,602 B2
• Filed: 02/16/2005
• Issued: 08/01/2006
• Est. Priority Date: 02/17/2004
• Status: Active Grant

• Current Assignee: Railpower, LLC
• Original Assignee: Railpower Technologies Corp.
• Inventors: Swan, David Herman, Donnelly, Frank Wegner, Watson, John David
• Primary Examiner(s): IP, SHIK LUEN PAUL
• Application Number:
  US11/060,087
• Publication Number:
  US 20050189886A1
• Time in Patent Office: 531 Days
• Field of Search: 318/139, 318/52, 318802-809, 180/65.5, 180/197, 303/177, 701/82, 701/90
• US Class Current: 318/807
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 2240/70 Interactions with external data bases, e.g. traffic centres
• CPC Class Codes: B60L 2260/46 by self learning
• CPC Class Codes: B60L 3/102 of individual wheels
• CPC Class Codes: B60T 8/1705 for rail vehicles
• CPC Class Codes: B61C 15/08 Preventing wheel slippage adjusting wheel-braking force to prevent wheel slippage B60T8/00 ; removing undesirable matter from the permanent way of railways E01H8/00
• CPC Class Codes: B61C 15/12 by reducing the driving power
• CPC Class Codes: B61C 15/14 controlling distribution of tractive effort between driving wheels
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y02T 30/00 Transportation of goods or passengers via railways, e.g. energy recovery or reducing air resistance
• CPC Class Codes: Y02T 90/16 Information or communication technologies improving the operation of electric vehicles

Abstract

The present invention is directed to the termination of the occurrence of wheel slip/skid and prediction and prevention of the onset of wheel slip/skid in a locomotive. In one configuration, a lookup table of adhesion factors is used to predict the occurrence of wheel slip/skid.

Claims

1. A method, comprising:

(a) receiving a requested notch setting from a locomotive operator, the requested notch setting providing more power to a plurality of traction motors than a current notch setting;

(b) in response to the receiving step (a), determining whether wheel slip is likely for at least one wheel if the notch setting is implemented; and

(c) when wheel slip is likely to occur, at least one of;

(i) implementing the requested notch setting but adjusting at least one of a current level and a power level associated with the requested notch setting to inhibit the onset of wheel slip to the at least one wheel; and

(ii) ignoring the requested notch setting and maintaining the current notch setting.

2. The method of claim 1, wherein step (i) is performed, wherein a wheel driven by a first traction motor has a different adhesion factor than a wheel driven by a second traction motor, and determining step (b) is performed for each of the plurality of traction motors and further comprising:

for each of the plurality of traction motors, adjusting a corresponding power level to inhibit the onset of wheel slip in at least one wheel associated with the respective traction motor, whereby at least first and second traction motors receive different power levels at the requested notch setting.

3. The method of claim 1, wherein step (i) is performed and determining step (b) is performed for each of the plurality of traction motors and further comprising:

adjusting at least one of a current level and a power level supplied to the traction motors to inhibit the onset of wheel slip in at least one wheel associated with one of the traction motors, whereby the traction motors each receive a common power level at the requested notch setting.

4. The method of claim 1, wherein step (ii) is performed.

5. The method of claim 1, wherein the determining step (b) comprises the substeps:

comparing at least one of (i) a torque associated with the requested notch setting, (ii) a traction motor electrical current and/or current derivative associated with the requested notch setting, (iii) a tractive effort associated with the requested notch setting, and (iv) a traction motor speed associated with the requested notch setting with a determined set of variables comprising a respective one of (i) a torque, (ii) a traction motor electrical current and/or current derivative, (iii) a tractive effort, and (iv) a traction motor speed indicating when wheel slip is likely to occur; and

when the at least one of (i) a torque associated with the requested notch setting, (ii) a traction motor electrical current and/or current derivative associated with the requested notch setting, (iii) a tractive effort associated with the requested notch setting, and (iv) a traction motor speed associated with the requested notch setting has a predetermined relationship with the respective one of (i) a torque, (ii) a traction motor electrical current and/or current derivative , (iii) a tractive effort, and (iv) a fraction motor speed in the determined set of variables, the predetermined relationship indicating that wheel slip is likely to occur, step (c) is performed.

6. The method of claim 5, wherein a tractive effort associated with the requested notch setting is compared with the determined set of variables.

7. The method of claim 5, wherein a traction motor electrical current associated with the requested notch setting is compared with the determined set of variables.

8. The method of claim 5, wherein an axle speed associated with the requested notch setting is compared with the determined set of variables.

9. The method of claim 5, wherein a traction motor speed associated with the requested notch setting is compared wit the determined set of variables.

10. The method of claim 5, wherein the determined set of variables is derived from an operational wheel slip history of the locomotive.

11. The method of claim 5, wherein a first set of variables corresponds to a first set of locomotive speed, track and/or environmental conditions and a second set of variables corresponds to a second different set of locomotive speed, track and/or environmental conditions and wherein the determining step (b) comprises:

selecting an appropriate set of variables for the current locomotive speed, track and/or environmental conditions.

12. A logic circuit operable to perform the steps of claim 5.

13. A locomotive, comprising:

(a) an operator interface operable to receive a requested notch setting from a locomotive operator, the requested notch setting providing more power to a plurality of traction motors than a current notch setting;

(b) a controller operable to determine, in response to the requested notch setting, whether wheel slip is likely for at least one wheel if the notch setting is implemented and, when wheel slip is likely to occur, cause the performance of at least one of the following operations;

(i) implementing the requested notch setting but adjusting at least one of a current level and a power level associated with the requested notch setting to inhibit the onset of wheel slip; and

(ii) ignoring the requested notch setting and maintaining the current notch setting.

14. The locomotive of claim 13, wherein operation (i) is performed, wherein a wheel driven by a first traction motor has a different adhesion factor than a wheel driven by a second traction motor, wherein the determining operation is performed for each of the plurality of traction motors and wherein the controller is further operable, for each of the plurality of traction motors, to adjust a corresponding power level to inhibit the onset of wheel slip in at least one wheel associated with the respective traction motor, whereby at least first and second traction motors receive different power levels at the requested notch setting.

15. The locomotive of claim 13, wherein operation (i) is performed and the determining operation is performed for each of the plurality of traction motors and wherein the controller is further operable to adjust a power level supplied to the traction motors to inhibit the onset of wheel slip in at least one wheel associated with one of the traction motors, whereby the traction motors each receive a common power level at the requested notch setting.

16. The locomotive of claim 13, wherein operation (ii) is performed.

17. The locomotive of claim 13, wherein the determining operation comprises the suboperations of:

comparing at least one of (i) a torque associated wit the requested notch setting, (ii) a traction motor electrical current and/or current derivative associated with the requested notch setting, (iii) a tractive effort associated wit the requested notch setting, and (iv) a traction motor speed associated with the requested notch setting with a determined set of variables comprising a respective one of (i) a torque, (ii) a traction motor electrical current and/or current derivative, (iii) a tractive effort, and (iv) a traction motor speed indicating when wheel slip is likely to occur; and

when the at least one of (i) a torque associated with the requested notch setting, (ii) a traction motor electrical current associated with the requested notch setting, (iii) a tractive effort associated with the requested notch setting, and (iv) a traction motor speed associated with the requested notch setting has a predetermined relationship with the respective one of (i) a torque, (ii) a traction motor electrical current, (iii) a tractive effort, and (iv) a traction motor speed in the determined set of variables, the determined relationship indicating that wheel slip is likely to occur, step (c) is performed.

18. The locomotive of claim 17, wherein a tractive effort associated with the requested notch setting is compared with the determined set of variables.

19. The locomotive of claim 17, wherein a traction motor electrical current associated with the requested notch setting is compared with the determined set of variables.

20. The locomotive of claim 17, wherein an axle speed associated with the requested notch setting is compared with the determined set of variables.

21. The locomotive of claim 17, wherein a traction motor speed associated with the requested notch setting is compared with the determined set of variables.

22. The locomotive of claim 17, wherein the set of variables is derived from an operational wheel slip history of the locomotive.

23. The locomotive of claim 17, wherein a first set of variables corresponds to a first set of locomotive speed, track and/or environmental conditions and a second set of variables corresponds to a second different set of locomotive speed, track and/or environmental conditions.

24. A method, comprising:

(a) in a locomotive comprising a plurality of fraction motors, each driving a plurality of wheels, monitoring at least one traction motor and/or at least one wheel driven by the at least one traction motor for the occurrence of at least one of wheel slip and wheel skid;

(b) when the at least one of wheel slip and wheel skid occurs, determining an operating characteristic in effect at a selected point before and/or during the occurrence of the at least one of wheel slip and wheel skid; and

(c) using the operating characteristic to predict a later possible occurrence of the at least one of wheel slip and wheel skid.

25. The method of claim 24, wherein the at least one of wheel slip and wheel skid is wheel slip.

26. The method of claim 25, wherein the monitoring step comprises:

incrementally increasing power to a selected fraction motor until wheel slip occurs to a wheel driven by the selected traction motor, whereby a set of operating characteristics characterizing the onset of wheel slip conditions may be generated;

upon the occurrence of wheel slip, reducing the wheel slip to a predetermined acceptable level by decreasing the power to a pre-wheel slip level.

27. The method of claim 25, wherein steps (a) and (b) are performed for each of the traction motors and wherein the operating characteristic is an adhesion coefficient.

28. The method of claim 27, wherein each traction motor has a respective adhesion coefficient characterizing at least one of the onset of wheel slip and the attainment of the optimum value of slip speed and wherein at least two traction motors have different adhesion coefficients.

29. The method of claim 27, wherein each of the adhesion coefficients is adjusted in magnitude by a safety factor and wherein each traction motor has a respective plurality of adhesion coefficients, each of which is associated with different locomotive speeds, track and/or climatic conditions.

30. The method of claim 25, wherein the at least one traction motor is the front traction motor and further comprising:

maintaining wheel slip for a time sufficient to condition a rail section over which the locomotive passes.

31. The method of claim 24, wherein, during a first time interval, steps (a) and (b) are performed for a first traction motor, wherein, during a second later time interval, steps (a) and (b) are performed for a second traction motor, and wherein the first and second time intervals are discrete from one another.

32. The method of claim 24, wherein the at least one of wheel slip and wheel skid is wheel skid.

33. The method of claim 32, wherein the determining step comprises the substep of:

detecting the operating characteristic of each of the plurality of traction motors and/or at least one wheel driven by each of the plurality of traction motors; and

wherein the operating characteristic is at least one of (i) an armature voltage of the corresponding traction motor, (ii) a rotational speed of one wheel driven by the corresponding traction motor, (iii) a rotational speed of the corresponding traction motor, (iv) a current and/or current derivative history of the corresponding traction motor, and (v) a commutator signature in the current of the corresponding traction motor, and wherein the determining step comprises at least one of;

(i) detecting an abrupt decrease to zero of the armature voltage of an individual traction motor,

(ii) detecting an abrupt decrease to zero in the revolutions-per-minute (rpms) of an individual an individual traction motor,

(iii) detecting an abrupt decrease to zero in the revolutions-per-minute (rpms) of an individual wheel or axle,

(iv) detecting an abrupt increase in the traction motor current or current time derivative, (v) detecting the disappearance of commutator noise in the traction motor current, and (vi) determining when a wheel speed has stopped relative to the true ground speed of the locomotive.

34. The method of claim 32, wherein a sensor independently monitors each of the traction motors and wherein the monitoring step comprises the substep of:

determining that the operating characteristic of the first traction motor has a predetermined relationship with an operating characteristic setpoint; and

further comprising;

comparing a detected operating characteristic detected for each of the traction motors to the operating characteristic setpoint and wherein, when the detected operating characteristic has the predetermined relationship with the operating characteristic setpoint, the at least one wheel of the corresponding traction motor is determined to be experiencing wheel skid.

35. The method of claim 32, wherein the operating characteristic is an adhesion coefficient, wherein each traction motor has a respective adhesion coefficient characterizing the onset of wheel skid and wherein at least two traction motors have different adhesion coefficients.

36. A locomotive, comprising:

a plurality of traction motors, each driving a plurality of wheels;

a sensor operable to monitor at least one traction motor and/or at least one wheel and/or at least one axle driven by the at least one traction motor for the occurrence of wheel slip; and

a controller operable to (i) predict the onset of wheel slip;

(ii) when wheel slip is likely to occur, implement an action to inhibit the onset of wheel slip;

(iii) when wheel slip occurs, determine an adhesion coefficient in effect at a selected point before and/or during the occurrence of wheel slip and use the adhesion coefficient to predict the onset of wheel slip, wherein the monitoring operation comprises the sub-operation of (a) incrementally increasing power to a selected traction motor until wheel slip occurs to a wheel driven by the selected traction motor, whereby a set of adhesion coefficients characterizing the onset of wheel slip conditions may be generated.

37. The locomotive of claim 36, wherein the monitoring operation comprises the sub-operation of, upon the occurrence of wheel slip, terminating the wheel slip by decreasing the power to a pre-wheel slip level.

38. The locomotive of claim 36, wherein the sensor independently monitors each of the traction motors.

39. The locomotive of claim 36, wherein each traction motor has a respective adhesion coefficient characterizing the onset of wheel slip and wherein at least two traction motors have different adhesion coefficients.

40. The locomotive of claim 36, wherein each of the adhesion coefficients is adjusted in magnitude by a safety factor and wherein each traction motor has a respective plurality of adhesion coefficients, each of which is associated with different locomotive speed, track and/or climatic conditions.

41. The locomotive of claim 36, wherein the at least one traction motor is the front traction motor and wherein the controller maintains wheel slip for a time sufficient to condition a rail section over which the locomotive passes.

42. The locomotive of claim 36, wherein the controller is operable, when wheel skid occurs, to determine an adhesion coefficient in effect at a selected point before and/or during the occurrence of wheel skid and use the adhesion coefficient to predict the onset of wheel skid.