Flow signal filter

• US 5,966,674 A
• Filed: 04/09/1997
• Issued: 10/12/1999
• Est. Priority Date: 04/09/1997
• Status: Expired due to Term

• Current Assignee: Westinghouse Air Brake Co (Westinghouse Air Brake Technologies Corporation)
• Original Assignee: Westinghouse Air Brake Co (Westinghouse Air Brake Technologies Corporation)
• Inventors: Bailey, Gary, Crawford, Charles, Dimsa, Robert D., Ferri, Vincent
• Primary Examiner(s): WACHSMAN, HAL D
• Application Number:
  US08/826,897
• Time in Patent Office: 916 Days
• Field of Search: 702/45-47, 702/50, 702/51, 702/85, 702/98, 702/100, 702/104, 702/105, 702/113, 702/114, 702/116, 702/138, 702/189-191, 702/197, 364/582.1, 364/528.16, 364/528.17, 364/528.36, 364/724.011, 364/724.013, 303/3, 303/15, 303/33, 73/861.42, 73/861.48, 73/861.49, 73/861.52, 73/861.61, 73/1.25, 73/1.34, 701/70, 701/71, 701/75-78, 701/81, 701/83, 377/19-21, 137/1, 137/624.11, 137/624.12, 137/624.15
• US Class Current: 702/47
• CPC Class Codes: B60T 13/665 the systems being specially adapted for transferring two or more command signals, e.g. railway systems B60T13/662 takes precedence

Abstract

Method and apparatus for providing a filtered signal which indicates of a flow of fluid to a fluid pressure communication conduit, the flow being dependent upon the pressure of fluid in a chamber. The pressure in the chamber is controlled by one or more pressure adjusting valves. The invention provides for receiving into a data processing module one or more valve signals indicating open states of the pressure adjusting valve or valves, and also a flowrate signal from a flowrate sensor, which represents the real instantaneous flowrate, and it is this signal which needs to be filtered to remove transients. The invention provides for choosing between a first processing mode and a second processing mode for the flowrate signal. The first processing mode is used when the second processing mode is not in effect, and when neither of the valve signals indicates an open valve. The second processing mode is activated a valve signal indicates an open valve. The second processing mode, when activated, proceeds according to a predetermined procedure and then returns to the first processing mode after no valve signal indicates an open valve. The signal is processed by either the first processing mode or the second processing mode, depending on whether valve signals have been received, and provides the filtered signal as an output to equipment external to the data processing module.

Claims

1. A method of providing a filtered signal indicative of a flow of fluid to a fluid pressure communication conduit, said flow dependent upon a pressure of fluid in a chamber, said pressure of fluid in said chamber controlled by at least one pressure adjusting valve, said method comprising:

(a) receiving into a data processing module at least one first signal indicative of an open state for at least one of said at least one pressure adjustment valve;

(b) receiving into said data processing module a second signal indicative of a value of a real instantaneous flowrate for said flow of fluid to said fluid pressure communication conduit;

(c) choosing between a first processing mode and a second processing mode for said second signal, said first processing mode during times when said second processing mode is not in effect, and when said at least one first signal does not indicate an open valve, said second processing mode activated when at least one of said at least one first signal indicates an open valve, said second processing mode, when activated, proceeding according to a predetermined procedure and then returning to said first processing mode when said at least one first signal indicates an open valve;

(d) said data processing module processing said second signal by said first processing mode and said second processing mode, as chosen in step (c), and providing said filtered signal indicative of said flow of said fluid as an output signal to equipment external to said data processing module.

2. A method according to claim 1 wherein said chamber is a chamber for a pilot pressure which controls flow rate through a flow control valve to maintain a pressure in said fluid pressure communication conduit at a predetermined value.

3. A method according to claim 1 wherein said first processing mode determines said output signal from an instantaneous value of said second signal.

4. A method according to claim 3 wherein said output signal determined in said first processing mode is identical to said second signal.

5. A method according to claim 1 wherein said second processing mode includes steps as follows, performed within said data processing module:

(i) starting at least one time counter indicating elapsed time since a beginning of said second processing mode;

(ii) determining a base flow value based on an instantaneous value of said second signal when said second processing mode is begun;

(iii) during a first filtering interval of said second processing mode, said first filtering interval terminating at a first predetermined time, determining said output signal to have a value corresponding to said base flow value;

(iv) at said first predetermined time, determining a required flowrate change from a current instantaneous value of said second signal;

(v) determining a generally monotonic function to transition between said base flow value and said base flow value changed by said required flowrate change, and beginning a second filtering interval wherein said output signal receives a value equal to said generally monotonic function;

(vi) terminating said second filtering interval if an instantaneous value of flow corresponding to said second signal becomes closer to said base flow value than said generally monotonic function; and

(vii) terminating said second filtering interval at a second predetermined time if not terminated in step (vi).

6. A method according to claim 5 wherein said generally monotonic function is a ramp function having a height equal to said required flowrate change.

7. A method according to claim 6 wherein said data processing module generates said ramp function by determining a number of timesteps between increments of said ramp function, said increments having a predetermined value, and incrementing said ramp function accordingly.

8. A method according to claim 7 wherein said predetermined value of said increments has a magnitude of unity.

9. A method according to claim 5 wherein said generally monotonic function has a predetermined duration terminating at said second predetermined time.

10. A method according to claim 5 wherein said at least one pressure adjusting valve includes a pressure increasing valve for increasing pressure in said chamber, an open condition of said pressure increasing valve signalled by a pressure increasing first signal and wherein said at least one pressure adjusting valve further includes a pressure decreasing valve for decreasing pressure in said chamber, an open condition of said pressure decreasing valve signalled by a pressure decreasing first signal, said method providing for a case in which said pressure increasing first signal has been received in said data processing module, placing it in said second processing mode, whereupon said pressure decreasing first signal is received in said data processing module, said method responding to this condition by interrupting said second processing mode, resetting said at least one time counter and returning to a second beginning of said second processing mode, an output signal during said first filtering interval of said second processing mode being set equal to an output signal prior to said second beginning.

11. A method according to claim 5 wherein said at least one pressure adjusting valve includes a pressure increasing valve for increasing pressure in said chamber, an open condition of said pressure increasing valve signalled by a pressure increasing first signal and wherein said at least one pressure adjusting valve further includes a pressure decreasing valve for decreasing pressure in said chamber, an open condition of said pressure decreasing valve signalled by a pressure decreasing first signal, said method providing for a case in which said pressure decreasing first signal has been received in said data processing module, placing it in said second processing mode, whereupon said pressure increasing first signal is received in said data processing module, said method responding to this condition by interrupting said second processing mode, resetting said at least one time counter and returning to a second beginning of said second processing mode, an output signal during said first filtering interval of said second processing mode being set equal to an output signal prior to said second beginning.

12. A method according to claim 1 wherein said at least one pressure adjustment valve is activated by at least one electrical valve actuation signal, said method further including the process of obtaining said at least one first signal from said at least one electrical valve actuation signal.

13. An apparatus for providing a filtered signal indicative of a flow of fluid to a fluid pressure communication conduit, such flow dependent upon a pressure of fluid in a chamber, such pressure of fluid in such chamber controlled by at least one pressure adjusting valve, said apparatus comprising:

(a) a data processing module connected to receive at least one first signal indicative of an open state for at least one of such at least one pressure adjustment valve, said data processing module further connected to receive a second signal from a flowmeter, such second signal indicative of such flow of fluid to such fluid pressure communication conduit;

(b) means disposed in said data processing module for choosing between a first processing mode and a second processing mode for such second signal, said first processing mode during times when said second processing mode is not in effect, and when such at least one first signal does not indicate an open valve, said second processing mode activated when such at least one first signal indicates an open valve, said second processing mode, when activated, proceeding according to a predetermined procedure and then returning to such first processing mode when such at least one first signal indicates an open valve;

(c) said data processing module processing such second signal by said first processing mode and said second processing mode, as chosen in step (b), and providing said filtered signal indicative of such flow of such fluid as an output signal to equipment external to said data processing module.

14. An apparatus according to claim 13 wherein such chamber is a chamber for a pilot pressure which controls flow rate through a flow control valve to maintain a pressure in such fluid pressure communication conduit at a predetermined value.

15. An apparatus according to claim 13 wherein said first processing mode determines said output signal from an instantaneous value of such second signal.

16. An apparatus according to claim 15 wherein said output signal determined in said first processing mode is identical to such second signal.

17. An apparatus according to claim 13 wherein said data processing module further includes:

(i) at least one time counter and means for starting said at least one time counter at a beginning of said second data processing mode;

(ii) means for determining a base flow value based on an instantaneous value of such second signal when said second processing mode is begun;

(iii) means for determining said output signal from said base flow value during a first filtering interval, said first filtering interval terminating at a first predetermined time;

(iv) means for determining a required flowrate change from said base flow value to a flow value based on an instantaneous value of such second signal at said first predetermined time;

(v) means for determining a generally monotonic function to transition between said base flow value and said base flow value changed by said required flowrate change, and for beginning a second filtering interval wherein said output signal receives a value equal to said generally monotonic function;

(vi) means for terminating said second filtering interval if an instantaneous value of flow corresponding to such second signal becomes closer to said base flow value than said generally monotonic function; and

(vii) means for terminating said second filtering interval at a second predetermined time if not terminated in step (vi).

18. An apparatus according to claim 17 wherein said generally monotonic function is a ramp function having a height equal to said required flowrate change.

19. An apparatus according to claim 18 wherein said data processing module generates said ramp function by determining a number of timesteps between increments of said ramp function, said increments having a predetermined value, and incrementing said ramp function by successive additions.

20. An apparatus according to claim 19 wherein said predetermined value of said increments has a magnitude of unity.

21. An apparatus according to claim 17 wherein said generally monotonic function has a predetermined duration terminating at said second predetermined time.

22. An apparatus according to claim 17 wherein such at least one pressure adjusting valve includes a pressure increasing valve for increasing pressure in such chamber, an open condition of such pressure increasing valve signalled by a pressure increasing first signal and wherein such at least one pressure adjusting valve further includes a pressure decreasing valve for decreasing pressure in such chamber, an open condition of such pressure decreasing valve signalled by a pressure decreasing first signal, said apparatus providing for a case in which such pressure increasing first signal has been received in said data processing module, placing it in said second processing mode, whereupon such pressure decreasing first signal is received in said data processing module, said apparatus responding to this condition by interrupting said second processing mode, resetting said at least one time counter and returning to a second beginning of said second processing mode, an output signal during said first filtering interval of said second processing mode being set equal to an output signal prior to said second beginning.

23. An apparatus according to claim 17 wherein such at least one pressure adjusting valve includes a pressure increasing valve for increasing pressure in such chamber, an open condition of such pressure increasing valve signalled by a pressure increasing first signal and wherein such at least one pressure adjusting valve further includes a pressure decreasing valve for decreasing pressure in such chamber, an open condition of such pressure decreasing valve signalled by a pressure decreasing first signal, said apparatus providing for a case in which such pressure decreasing first signal has been received in said data processing module, placing it in a second processing mode, whereupon such pressure increasing first signal is received in said data processing module, said apparatus responding to this condition by interrupting said second processing mode, resetting said at least one time counter and returning to a second beginning of said second processing mode, an output signal during said first filtering interval of said second processing mode being set equal to an output signal prior to said second beginning.

24. An apparatus according to claim 13 wherein such at least one pressure adjustment valve is activated by at least one electrical valve actuation signal, said apparatus further including means connected to such electrical valve actuation signal for obtaining such at least one first signal from such at least one electrical valve actuation signal.

25. An apparatus for providing an output signal indicative of a filtered value of airflow to a brakepipe of a locomotive, a pneumatic valve determining such airflow causing a pressure of such brakepipe to follow a pressure in an equalizing chamber, such equalizing chamber having pressure adjusted upward by an electrically activated charge valve and adjusted downward by an electrically activated discharge valve, said apparatus comprising:

(a) a data processing module connected to receive a charge valve signal indicative of an open condition for such charge valve, said data processing module further connected to receive a discharge valve signal indicative of an open condition for such discharge valve, said data processing module further connected to receive a flow rate signal from a flow sensor in a supply path to such brakepipe, such flow sensor in series with such pneumatic valve;

(b) means disposed in said data processing module for choosing between a first processing mode and a second processing mode for such flowrate signal, said first processing mode during times when said second processing mode is not in effect and when neither of such charge signal nor such discharge signal is present, such first processing mode determining said output signal directly from an instantaneous value of such flowrate signal, said first processing mode terminating and said second processing mode beginning on receipt of at least one of such charge signal and such discharge signal;

(c) means disposed in said data processing module for implementing said second processing mode, said means including;

(i) at least one time counter and means for starting said at least one time counter when said second processing mode is started;

(ii) means for determining a base flow value based on a first instantaneous value of such flowrate signal when said second processing mode has begun;

(iii) means for setting said output signal equal to a value of said base flow value during a first filtering interval terminating at a first predetermined time, as indicated by at least one of said at least one time counter;

(iv) means for determining a required change in output signal from said base flow value to a second instantaneous flow value from such flowrate signal, said second instantaneous value prevailing at said first predetermined time;

(v) means for transitioning said output signal from said base flow value to said second instantaneous value base flow value during a second filtering interval terminating at a second predetermined time;

(vi) means for terminating said second filtering interval and returning to said first processing mode at said second predetermined time; and

(vii) means for terminating said second filtering interval prior to said second predetermined time if such flowrate signal becomes closer to said base flow value than said output signal.

26. An apparatus according to claim 25 further characterized as connected to receive a transition signal indicative of a transition from such charge valve signal to such discharge valve signal, said apparatus having means for terminating said second filtering interval prior to said second predetermined time if such transition signal is received in said data processing module, said apparatus also having means activated by such transition signal for resetting said at least one time counter and repeating said first filtering interval and said second filtering interval, determining said base flow value from a value of said output signal prevailing when such transition signal was received.

27. An apparatus according to claim 25 further characterized as connected to receive a transition signal indicative of a transition from such discharge valve signal to such charge valve signal, said apparatus having means for terminating said second filtering interval prior to said second predetermined time if such transition signal is received in said data processing module, said apparatus also having means activated by such transition signal for resetting said at least one time counter and repeating said first filtering interval and said second filtering interval, determining said base flow value from a value of said output signal prevailing when such transition signal was received.