Flow signal filter

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.

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.