Weigh feeding apparatus

• US 4,320,855 A
• Filed: 02/28/1980
• Issued: 03/23/1982
• Est. Priority Date: 12/07/1976
• Status: Expired

• Current Assignee: Acrison, Inc.
• Original Assignee: Acrison, Inc.
• Inventors: Hartmann, Joseph L., Lauterbach, Gary R., Ricciardi, Ronald J., Ferrara, Angelo
• Primary Examiner(s): MILLER JR, GEORGE
• Application Number:
  US06/125,370
• Time in Patent Office: 754 Days
• Field of Search: 222/55, 222/58, 222/63, 222/56, 177/50, 177/185, 364/479
• US Class Current: 222/56
• CPC Class Codes: G05D 7/0605 specially adapted for solid materials
• CPC Class Codes: G05D 7/0611 characterised by the set value given to the control element

Abstract

Disclosed herein is an automatically controlled weigh feeding apparatus including a container for prefilling with a substance, a device for discharging the substance from the container at a controllable rate, apparatus for weighing the substance being discharged and for producing an electrical signal proportional to that weight, a voltage to frequency converter connected to receive the electrical signals, a digital computer, apparatus coupled to an output of the voltage to frequency converter for inputting data signals to the digital computer, the computer being adapted to compute a corrective signal based on the input data signals received, and coupling apparatus coupled between the computer and the device for discharging the substance from the container for controlling the rate of discharge responsive to the corrective signal.

Claims

1. A weigh feeding machine comprising

a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

means for producing a first electrical signal corresponding to the desired feed-out rate;

means for sensing the weight of at least the substance in the container and for producing a second electrical signal having a characteristic which is proportional to the value of said weight;

means for sampling said second electrical signal during each of a succession of time intervals;

means for computing a feed-out rate from signals derived from said sampling and for comparing an electrical signal representative of said computed feed-out rate with the first electrical signal, and for producing, as a result of said comparison, a control electrical signal indicative of the desired changes, if any, in the feed-out rate of the discharge means;

control means for controlling the discharging means in accordance with said control electrical signal to thereby maintain the feed-out of the substance from the container at the desired feed-out rate; and

means for comparing a signal derived from at least one sample taken during one of said time intervals with a signal derived from at least one sample taken during another of said time intervals, for repeating said comparison for successive time intervals, so that the signal derived during each of said successive time intervals is compared with a signal derived during a different time interval, and for inhibiting the action of the control electrical signal on the control means when said comparison shows a difference between the compared signals beyond a predetermined limit.

2. A weigh feeding machine according to claim 1, wherein the comparison and inhibiting means compares a signal derived during each time interval with a signal derived during the immediately preceding time interval.

3. A weigh feeding machine according to claim 2, wherein, when the last-mentioned comparison produces a difference beyond said predetermined limit, said inhibiting means inhibits the control electrical signal so as to permit the feed-out rate to continue at a rate established by at least one preceding control electrical signal.

4. A weigh feeding machine comprising a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

storage means for storing a first electrical signal corresponding to the desired feed-out rate;

means for sensing the weight of at least the substance in the container and for producing a second electrical signal at a frequency which corresponds to the value of said weight and changes for the different values of weight sensed;

means for sampling the second electrical signal during each of a succession of time intervals;

digital circuit means for comparing an electrical signal derived from said sampling of said second electrical signal with an electrical signal derived from said first electrical signal, for producing, as a result of said comparisons, control electrical signals indicative of the desired changes, if any, in the feed-out rate of the discharge means;

control means for controlling the discharging means in accordance with said control electrical signal to thereby maintain the feed-out of the substance from the container at the desired feed-out rate;

means for comparing a signal derived from at least one sample taken during one of said time intervals with a signal derived from at least one sample taken during another of said time intervals, for repeating said comparison for successive time intervals, so that the signal derived during each of said successive time intervals is compared with a signal derived during a different time interval, and for inhibiting the action of the control electrical signals on the control means when said comparison shows a difference between the compared signals beyond a predetermined limit.

5. A weigh feeding machine comprising a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

means for producing a first electrical signal corresponding to the desired feed-out rate;

means for sensing the weight of at least the substance in the container and for producing a second electrical signal proportional to the value of said weight;

digital circuit means for comparing an electrical signal derived from said sampling of said second electrical signal with an electrical signal derived from the first electrical signal, for producing, as a result of said comparison, a control electrical signal indicative of the desired changes, if any, in the feed-out rate of the discharge means;

control means for controlling the discharging means in accordance with said control electrical signal to thereby maintain the feed-out of the substance from the container at the desired feed-out rate;

means for comparing a signal derived from said second electrical signal during each of a succession of time intervals with a signal derived from said second electrical signal during a different one of said time intervals; and

means, responsive to said comparisons of signals derived from said second electrical signal during successive time intervals, for inhibiting the control means when said comparison shows a difference between the compared signals beyond a predetermined limit and for establishing a feed-out rate corresponding to the value of at least one preceding control electrical signal.

6. A weigh feeding machine according to claim 5 wherein said sampling and comparing means compares a signal derived from at least one sample taken during each time interval with a signal derived from at least one sample taken during the immediately preceding time interval.

7. A weigh feeding machine comprising a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

storage means for storing a first electrical signal corresponding to the desired feed-out rate;

means for sensing the weight of the container and its contents and for producing a second electrical signal at a frequency which corresponds to the value of said weight;

digital circuit means for sampling the second electrical signal during each of a succession of time intervals;

storage means for storing the frequency signals representative of the samples of said second electrical signal during such succession of time intervals;

digital computer means for computing a succession of feed-out rates from the frequency signals corresponding to the samples taken during said successive time intervals, and for comparing an electrical signal representative of each said computed feed-out rate with the first electrical signal representative of said desired feed-out rate, for producing, as a result of said comparisons, control electrical signals indicative of the desired changes, if any, in the feed-out rate of the discharge means;

control means for controlling the discharging means in accordance with said control electrical signals to thereby maintain the feed-out of the substance from the container at the desired feed-out rate; and

means for comparing a signal derived from at least one sample taken during one of said time intervals with a signal derived from at least one sample taken during another of said time invervals, for repeating said comparison for successive time intervals, so that the signal derived during each of said successive time intervals is compared with a signal derived during a different time interval, and for inhibiting the action of the control electrical signal on the control means when said comparison shows a difference between the compared signals beyond a predetermined limit.

8. A weigh feeding machine comprising a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

storage means for storing a first electrical signal corresponding to the desired feed-out rate;

means for sensing the weight of the substance discharged from the container and for producing a second electrical signal at a frequency which corresponds to the instantaneous value of said weight;

digital circuit means for sampling the second electrical signal during each of a succession of time intervals;

storage means for storing the frequency signals representative of the samples of said second electrical signal;

digital circuit means for comparing electrical signals derived from said sampling of said second electrical signal with an electrical signal derived from the first electrical signal, for producing, as a result of said comparison, a control electrical signal indicative of the desired changes, if any, in the feed-out rate of the discharge means;

control means for controlling the discharging means in accordance with said control electrical signal to thereby maintain the feed-out of the substance from the container at the desired feed-out rate;

means for comparing a signal derived from samples taken during each of a succession of said time intervals with a signal derived from said second electrical signal during a different one of said time intervals; and

means, responsive to the last-mentioned comparisons, for inhibiting the control means when said comparison shows a difference between the compared signals beyond a predetermined limit and for establishing a feed-out rate corresponding to the value of a least one preceding control electrical signal.

9. A weigh feeding machine comprising a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

storage means for storing a first electrical signal corresponding to the desired feed-out rate;

means for sensing the weight of at least the substance in the container and for producing a second electrical signal at a frequency which corresponds to the value of said weight and changes for the different values of weight sensed;

digital circuit means for sampling the second electrical signal successively, each sampling including a predetermined number of periods of said second electrical signal;

said digital circuit means sampling said second electrical signal a plurality of times during each of a succession of time intervals;

storage means for storing the samples of said second electrical signal during each such time interval;

digital computer means for computing a feed-out rate during each such time interval, from the samples taken during such time interval, and for comparing an electrical signal representative of said computed feed-out rate with the first electrical signal representative of said desired feed-out rate, for producing, as a result of said comparison, a control electrical signal indicative of the desired changes, if any, in the feed-out rate of the discharge means;

control means for controlling the discharging means in accordance with said control electrical signal to thereby maintain the feed-out of the substance from the container at the desired feed-out rate; and

means for comparing a signal derived from at least one sample taken during one of said time intervals with a signal derived from at least one sample taken during another of said time intervals, for repeating said comparison for successive time intervals, so that the signal derived during each of said successive time intervals is compared with a signal derived during a different time interval, and for inhibiting the action of the control electrical signal on the control means when said comparison shows a difference between the compared signals beyond a predetermined limit.

10. A weigh feeding machine according to claim 9, wherein,

during each sampling, said digital circuit means samples said second electrical signal for a number of periods of said second signal which varies inversely with the value of the desired feed-out rate.

11. A weigh feeding machine according to claim 9, wherein,

during each time interval, said digital circuit means samples said second electrical signal a number of times which varies inversely with the desired feed-out rate.

12. A weigh feeding machine according to claim 9, wherein

said means for comparing compares the signal representative of the computed feed-out rate for each time interval with the signal representative of the computed feed-out rate for at least one preceding time interval.

13. A weigh feeding machine according to claim 9, wherein the comparison means for the computed feed-out rate compares the signal representative of each computed feed-out rate with the signal representative of the computed feed-out rate for the immediately preceding time interval.

14. A weigh feeding machine according to claim 9, wherein, when the comparison between the signals for the computed feed-out rates for different time intervals is beyond said predetermined limit, said inhibiting means inhibits any control electrical signal from being transmitted to the control means, so that the feed-out rate continues at the rate to which it was last corrected.

15. A weigh feeding machine according to claim 9, wherein,

the digital circuit means includes a high frequency oscillator having an operating frequency at least an order of magnitude higher than the frequency corresponding to the value of the weight being sensed;

gating means coupled to said high frequency oscillator; and

second control means for enabling said gating means for a period of time corresponding to a predetermined number of periods of the frequency corresponding to the weight being sensed, to pass signals from said high frequency oscillator during said period of time, to thereby convert the frequency of the weight being sensed to said high frequency.

16. A weigh feeding machine according to claim 15, wherein said second control means enables the gating means for a predetermined number of periods which varies inversely with the value of the desired feed-out rate.

17. A weigh feeding machine according to claim 15, further including

storage means for storing the signals from said high frequency oscillator;

and

multiplexing means coupled to said storage means for multiplexing the different portions of the high frequency signal out of said storage means in a predetermined sequence.

18. A weigh feeding machine according to claim 15, wherein

said gating means includes a first gating means for the low frequency second electrical signal and a second gating means for the high electrical signal from said oscillator;

and

said second control means enables said first and second gating means simultaneously;

further including

a first counter coupled to said first gating means for counting the periods of said low frequency second electrical signal,

a second counter coupled to said second gating means for counting the periods of said high frequency electrical signal, and

disabling means responsive to said first counter reaching a predetermined count for disabling said second gating means.

19. A weigh feeding machine according to claim 18, wherein said disabling means includes a comparison circuit coupled to said first counter for producing a disabling signal when said first counter has reached a predetermined count, for disabling said first and second gating means.

20. A weigh feeding machine comprising a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

storage means for storing a first electrical signal corresponding to the desired feed-out rate;

means for sensing the weight of at least the substance in the container and for producing a second electrical signal at a frequency which corresponds to the value of said weight and changes for the different values of weight sensed;

digital circuit means for sampling the second electrical signal a plurality of times during a predetermined time interval, for a succession of said time intervals;

said digital circuit means including circuit means for converting the frequency of the sampled signal to a higher frequency which is a least an order of magnitude higher than the frequency of the sampled signal;

storage means for storing the higher frequency signals representative of the samples of said second electrical signal during each such time interval;

digital computer means for computing a feed-out rate during each such time interval, from the higher frequency signals corresponding to the samples taken during one such time interval, and for comparing an electrical signal representative of said computed feed-out rate with the first electrical signal representative of said desired feed-out rate, for producing, as a result of said comparison, a control electrical signal indicative of the desired changes, if any, in the feed-out rate of the discharge means;

control means for controlling the discharging means in accordance with said control electrical signal to thereby maintain the feed-out of the substance from the container at the desired feed-out rate; and

means for comparing the signal representative of the computed feed-out rate for each such time interval with the signal representative of the computed feed-out rate for at least one preceding time interval; and

inhibiting means, responsive to said comparison of computed feed-out rates, for inhibiting the action of the control electrical signal on the control means when said comparison shows a difference between the computed feed-out rates beyond a predetermined limit.

21. A weigh feeding machine according to claim 20 wherein said digital circuit means samples said second electrical signal for a predetermined number of its periods during each sampling, and produces a larger number of periods at the higher frequency extending over substantially the same time duration.

22. A weigh feeding machine according to claim 20, wherein said digital circuit means includes a high frequency oscillator having an operating frequency at least an order of magnitude higher than the frequency corresponding to the value of the weight being sensed;

gating means coupled to said high frequency oscillator; and

second control means for enabling said gating means for a period of time corresponding to a predetermined number of periods of the frequency corresponding to the weight being sensed, to pass signals from said high frequency oscillator during said period of time, to thereby convert the frequency of the weight being sensed to said high frequency.

23. A weigh feeding machine comprising a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

storage means for storing a first electrical signal corresponding to the desired feed-out rate;

means for sensing the weight of at least the substance in the container and for producing a second electrical signal having a characteristic which corresponds to the value of said weight;

said digital circuit means sampling said second electrical signal a plurality of times during each of a succession of time intervals;

storage means for storing the samples of said second electrical signal during each such time interval;

digital computer means for computing a feed-out rate during each such time interval, from the samples taken during one such time interval, and for comparing an electrical signal representative of said computed feed-out rate with the first electrical signal representative of said desired feed-out rate, for producing, as a result of said comparison, a control electrical signal indicative of the desired changes, if any, in the feed-out rate of the discharge means;

control means for controling the discharging means in accordance with said control electrical signal to thereby maintain the feed-out of the substance from the container at the desired feed-out rate; and

means for comparing a signal derived from at least one sample taken during one of said time intervals with a signal derived from at least one sample taken during another of said time intervals, for repeating said comparison for successive time intervals, so that the signal derived during each of said successive time intervals is compared with a signal derived during a different time interval, and for inhibiting the action of the control electrical signal on the control means when said comparison shows a difference between the compared signals beyond a predetermined limit.

24. A weigh feeding machine according to claim 23, wherein the means for comparing the signals derived from samples taken in different time invervals compares the signal representative of each computed feed-out rate with the signal representative of the computed feed-out rate for the immediately preceding time interval.

25. A weigh feeding machine according to claim 23, wherein, when comparison between the signals derived from samples taken in different time intervals is beyond said predetermined limit, said inhibiting means inhibits any control electrical signal from being transmitted to the control means, so that the feed-out rate continues at the rate to which it was last corrected.

26. A weigh feeding device comprising

a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

storage means for storing a first electrical signal corresponding to the desired feed-out rate;

means for sensing the weight of at least the substance in the container;

first circuit means responsive to said sensing means for producing a succession of second electrical signals, each at a frequency which is responsive to the value of the weight sensed;

counting means for counting the cycles of each of said second electrical signals to produce a succession of total counts, each of which is a measure of the value of the weight sensed;

a digital circuit for storing said total counts and comparing an electrical signal responsive to a plurality of said total counts with the first electrical signal representative of said desired feed-out rate, for producing, as a result of said comparison, a control electrical signal indicative of the desired changes, if any, in the feed-out rate of the discharge means; and

control means for controlling the discharge means in accordance with said control electrical signal to thereby maintain the feed-out of the substance from the container at the desired feed-out rate.

27. A weigh feeding device according to claim 26, wherein

said digital circuit includes means for computing one or more error limits in the form of deviations from the computed feed-out rate;

and

means operative in computing the feed-out rate, for excluding from the computation thereof any total count values which fall beyond said error limits.

28. A weigh feeding device comprising

a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

storage means for storing a first electrical signal corresponding to the desired feed-out rate;

a voltage source for producing an output voltage at a predetermined number of cycles per second;

means for sensing the weight of at least the substance in the container and producing a second electrical signal responsive to said weight;

circuit means responsive to said second electrical signal for gating a succession of cycles of said output voltage from said voltage source for a period of time, the duration of which is dependent upon the value of said weight;

counting means for counting the cycles gated from said source to produce a total count which is a measure of the value of the weight being sensed;

a digital circuit for comparing an electrical signal responsive to said total count with the first electrical signal representative of said desired feed-out rate, for producing, as a result of said comparison, a control electrical signal indicative of the desired changes, if any, in the feed-out rate of the discharge means; and

control means for controlling the discharge means in accordance with said control electrical signal to thereby maintain the feed-out of the substance from the container at the desired feed-out rate.

29. A weigh feeding device according to claim 28, wherein

said circuit means includes sampling means for repeatedly sampling the second electrical signal from said sensing means;

each such sample controlling the period of time over which the output from said voltage source is gated;

said counting means counting the cycles gated from said source for each said sampling and producing a series of total counts, one for each of said samplings;

storage means for storing all of said total counts; and

said digital circuit computing the feed-out rate from a plurality of the total counts which occur during a predetermined time interval.

30. A weigh feeding device comprising

a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

storage means for storing a first electrical signal corresponding to the desired feed-out rate;

means for sensing the weight of at least the substance in the container and for producing a second electrical signal which corresponds to the value of said weight;

a voltage source for producing an output signal at a predetermined frequency;

counting means for counting the signals from said voltage source;

a digital circuit for sampling the second electrical signal successively and, for each such sampling, gating output signals from said voltage source to said counting means for a period of time which corresponds to a characteristic of said second electrical signal;

storage means for storing a plurality of values corresponding to the total counts of said counting means for all of said samplings;

digital computer means for computing a feed-out rate from the total counts for a plurality of said samples, and for comparing an electrical signal representative of said computed feed-out rate with the first electrical signal representative of said desired feed-out rate, for producing, as a result of said comparison, a control electrical signal indicative of the desired changes, if any, in the feed-out rate of the discharge means; and

control means for controlling the discharge means in accordance with said control electrical signal to thereby maintain the feed-out of the substance from the container at the desired feed-out rate.

31. A weigh feeding device according to claim 30, further including

circuit means controlled by said digital computer for initiating each successive period of time for which output signals from said voltage source are gated to said counting means, and

said digital circuit terminating each such successive period of time at a time which corresponds to the value of the characteristic of the second electrical signal.

32. A weigh feeding device comprising

a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

means for establishing a first electrical signal corresponding to the desired feed-out rate;

source means for producing an output signal at a predetermined frequency;

counting means coupled to said source means for receiving and counting the signals therefrom;

means for sensing the weight of at least the substance in the container and for producing a second electrical signal having a frequency which corresponds to the value of said weight;

digital circuit means for repeatedly sampling said second signal and controlling the count of said counting means, during each such sampling, to count to the frequency of said second signal at the time of said sampling;

storage means for storing a plurality of values, each corresponding to the count of said counting means for one of said samplings;

digital computer means for computing a feed-out rate for each of a succession of time intervals, from the count samples during one such time interval, and for comparing an electrical signal representative of said computed feed-out rate with the first electrical signal representative of said desired feed-out rate, for producing, as a result of said comparison, a control electrical signal indicative of the desired changes, if any, in the feed-out rate of the discharge means; and

control means for controlling the discharging means in accordance with said control electrical signal to thereby maintain the feed-out of the substance from the container at the desired feed-out rate.

33. A weigh feeding device comprising

a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

means for establishing a first electrical signal corresponding to the desired feed-out rate;

means for sensing the weight of at least the substance in the container and for producing a second electrical signal having a characteristic which corresponds to the value of said weight;

a source of signals at a predetermined frequency;

a counter for counting the signals from said source;

storage means for storing a succession of values corresponding to counts of said counter;

digital circuit means for sampling the second electrical signal successively and for transmitting from said counter to said storage means, for each such sampling, a value corresponding to the count of the counter for a period of time proportional to the weight sensed;

digital computer means for computing a feed-out rate from a plurality of said count values, and for comparing an electrical signal representative of said computed feed-out rate with the first electrical signal representative of said desired feed-out rate, for producing, as a result of said comparison, a control electrical signal indicative of the desired changes, if any, in the feed-out rate of the discharge means; and

control means for controlling the discharge means in accordance with said control electrical signal to thereby maintain the feed-out of the substance from the container at the desired feed-out rate.

34. A weigh feeding device according to claim 33 wherein

the sensing means produces an electrical signal whose frequency corresponds to the value of the weight being sensed;

further including second counting means for counting the signals from said sensing means; and

means responsive to the count in said second counting means for controlling said period of time for said first counting means.

35. A weigh feeding machine comprising a container for a substance;

discharge means for discharging the substance from the container at a controllable feed-out rate;

means for producing a first electrical signal corresponding to the desired feed-out rate;

means for sensing the weight of at least the substance in the container and for producing a second electrical signal having a characteristic which is proportional to the value of said weight;

digital circuit means for sampling said second electrical signal at least once during each of a succession of time intervals;

means for computing a feed-out rate during each of said time intervals from signals derived from said sampling and for comparing an electrical signal representative of each such computed feed-out rate with the first electrical signal representative, for producing, as a result of said comparison, control electrical signals indicative of the desired changes, if any, in the feed-out rate of the discharge means;

control means for controlling the discharging means in accordance with said control electrical signals to thereby maintain the feed-out of the substance from the container at the desired feed-out rate; and

means for comparing a signal derived from at least one sample taken during one of said time intervals with a signal derived from at least one sample taken during another of said time intervals, for repeating said comparison for successive time intervals, so that the signal derived during each of said successive time intervals is compared with a signal derived during a different time interval, and for inhibiting the action of the control electrical signal on the control means when said comparison shows a difference between the compared signals beyond a predetermined limit.

36. A weigh feeding machine according to claim 35, wherein the means for comparing the signals derived from samples taken in different time intervals compares a signal representative of each computed feed-out rate with a signal representative of the computed feed-out rate for the immediately preceding time interval.