Load weighing and accumulating system and method for hydraulic loader

• US 4,230,196 A
• Filed: 09/22/1978
• Issued: 10/28/1980
• Est. Priority Date: 09/22/1978
• Status: Expired due to Term

• Current Assignee: Kilo-Wate Incorporated
• Original Assignee: Edwin D. Snead
• Inventors: Snead, Edwin D.
• Primary Examiner(s): Miller, Jr., George H.
• Application Number:
  US05/945,075
• Time in Patent Office: 767 Days
• Field of Search: 177/1, 177/141, 177/145, 177/146, 177/165, 177/208, 177/210 R, 177/210 FP, 177/DIG. 3, 414/21
• US Class Current: 177/141
• CPC Class Codes: E02F 3/3411 of the Z-type
• CPC Class Codes: E02F 9/264 Sensors and their calibration for indicating the position of the work tool
• CPC Class Codes: G01G 19/083 lift truck scale
• CPC Class Codes: G01G 19/10 having fluid weight-sensitive devices
• CPC Class Codes: G01G 19/12 having electrical weight-sensitive devices
• CPC Class Codes: G01G 3/147 involving digital counting
• CPC Class Codes: G01G 5/06 with electrical indicating means

Abstract

A loader includes a lift arm assembly, raised by hydraulic lift cylinders and carrying a load bucket. Alignment members mounted respectively on the loader frame and lift arm assembly, and visible to the loader operator, identify the weigh position of the lift arm assembly. A pressure to voltage transducer is mounted on one lift cylinder, and is connected in a bridge circuit producing a DC voltage output. The bridge circuit output signal, proportional to the bucket load, is fed to an amplifier, whose output is passed to an analog-to-frequency converter producing pulses at a frequency proportional to the bucket load. An electronic clock allows the converter output pulses to pass through an AND gate to a bucket counter which displays the bucket load, and is automatically reset to zero. The converter pulses are passed to an accumulator counter through a second AND gate. The accumulator counter accumulates the weight of several bucket loads which are loaded onto a transport vehicle; and is reset manually after the vehicle is loaded.

Claims

1. A weight measuring and indicating system, for a loader having at least one hydraulic lift cylinder for elevating a load carrier, comprising

a transducer, for operative connection to said lift cylinder, for detecting instantaneous hydraulic pressure therein and for producing an instantaneous electric analog signal responsive to the instantaneous hydraulic pressure;

converter means coupled to the output of said transducer means for converting said analog signal to a frequency signal consisting of pulses generated at a frequency proportional to said analog signal;

a counter for counting and displaying the ouput pulses of said converter;

control gate means coupling said counter to said converter; and

clock means coupled to said gate means, for controlling the passing of converter output pulses to said counter whereby said counter display will be representative of the load in said carrier.

2. A system as set forth in claim 1

including an add switch coupled to said gate means for further controlling the passing of converter output pulses to said counter whereby said counter functions as an accumulator counter responsive to operation of said add switch;

and a manual reset switch associated with said counter.

3. A system as set forth in claim 2

wherein said electric signal fed to said converter is a voltage signal;

and a volt meter connected to the converter input circuit for visual display of the signal which is proportional to the instantaneous hydraulic pressure and to the load in the carrier.

4. A system as set forth in claim 1

including a loader comprising a frame, lift arms having one end pivotally mounted on said frame, a load carrier pivotally mounted at the other ends of said lift arms, at least one lift cylinder connected between said frame and said lift arms for raising and lowering said lift arms and carrier, and coacting members mounted on said frame and on said lift arm assembly for indicating to the operator a preselected weigh position of said lift arms relative to said frame.

5. A system as set forth in claim 4

actuator means for controlling said gate means including a flip-flop latch circuit the output of which is coupled to said control gate means;

an add switch for producing one input to said latch circuit, and said clock means coupled to said latch circuit for producing a second input to said latch circuit, thereby producing a latch circuit output to said control gate means;

a limit switch connected in series between said add switch and said latch circuit;

said limit switch mounted on one of said coacting indicating members; and

a trigger device for said limit switch mounted on the other of said coacting indicating members.

6. A system as set forth in claim 1

actuator means for controlling said gate means including a flip-flop latch circuit, the output of which is coupled to said control gate means;

an add switch for producing one input to said latch circuit, and said clock means coupled to said latch circuit for producing a second input to said latch circuit, thereby producing a latch circuit output to said control gate means.

7. A system as set forth in claim 6

a one-shot connected between said add switch and said latch circuit;

and filter means connected to the input of said one-shot to filter out extraneous input signals to said one-shot.

8. A system as set forth in claim 1

said transducer including a Wheatstone bridge circuit for producing an output current proportional to the hydraulic pressure;

a constant current amplifier for amplifying the output of said Wheatstone bridge circuit;

a variable load resistor connected to the output of said amplifier for producing a voltage signal proportional to the amplifier output current;

said voltage signal comprising said electric signal fed to said converter.

9. A system as set forth in claim 8

including a volt meter for detecting and displaying said voltage signal.

10. A system as set forth in claim 8

said variable load resistor functioning to adjust the input voltage to said converter, and serving as a calibration resistor for the system.

11. A system as set forth in claim 1

said clock producing clock pulses of preselected duration at preselected uniform time intervals;

said clock opening said gate means to pass output pulses from said converter to said counter during each of said clock pulses.

12. A system as set forth in claim 11

said gate means for said first named counter comprising a first AND gate;

a second counter coupled to the output of said converter by means of said first AND gate, and a second AND gate for coupling said second counter to said first AND gate;

said first counter having an automatic reset mechanism; and

means coupling said clock to said reset mechanism, for resetting said first counter responsive to initiation of a clock pulse;

and an add switch coupled to said second AND gate, operative with said first AND gate to open said second AND gate to pass pulses to said second counter.

13. A system as set forth in claim 12

actuator means for said second counter comprising a one shot coupled to one input of said second AND gate, a third AND gate having its output coupled to the input of said one shot, and said add switch;

and said clock and said add switch being coupled to said third AND gate as the inputs thereof.

14. A system as set forth in claim 12

actuator means for controlling said second AND gate including a flip-flop latch circuit, the output of which is coupled to said second AND gate;

said add switch for producing one input to said latch circuit, and said clock means coupled to said latch circuit for producing a second input to said latch circuit, thereby producing a latch circuit output to said second AND gate.

15. A method for weighing bulk material transferred from one location to another by means of a loading vehicle having a hydraulic lift cylinder for elevating a load carrier, comprising the steps

detecting the instantaneous pressure in said hydraulic lift cylinder, which pressure is a function of the weight of the load carrier and the carrier load;

converting said instantaneous pressure into an electric analog signal proportional to said instantaneous pressure;

adjusting said electric analog signal to eliminate the component thereof which represents the weight of the empty carrier;

converting said adjusted analog signal to a frequency signal consisting of pulses generated at a frequency proportional to said analog signal;

and counting the pulses of said frequency signal during a preselected time period, the count representing the instantaneous carrier load.

16. A method as set forth in claim 15, including the step

counting a significant number of pulses, during said preselected time period, to produce a reliable representation of said adjusted analog signal.

17. A method as set forth in claim 15, including the steps

positioning said vehicle load carrier in a preselected weigh position relative to the frame of said loading vehicle;

and detecting said detected analog signal only when said carrier is in said weigh position.

18. A method as set forth in claim 15, including the steps

counting the pulses of said frequency signal during a preselected time period for each load carried in the load carrier;

whereby the counting of pulses represents the accumulated load transferred as successive carrier loads.

19. A method as set forth in claim 15 including the steps

positioning said vehicle load carrier in a preselected weigh position relative to the frame of said loading vehicle;

and counting said pulses only when said carrier is in said weigh position.

20. A method as set forth in claim 19, wherein said loading vehicle includes at least one lift arm pivotally supported on the vehicle frame and said carrier is pivotally supported at the distal end of said lift arm, including the steps

positioning said lift arm at a preselected elevation relative to the vehicle frame, which defines said weigh position;

and rotating said carrier to a preselected position relative to said lift arms, which further defines said weight position.

21. A method as set forth in claim 15

counting the pulses of said frequency signal in first and second counters;

and controlling said second counter to count said pulses during only one preselected time interval for each carrier load, whereby said second counter accumulates the count of pulses representing successive carrier loads.

22. A method as set forth in claim 21

controlling said first counter to automatically reset between each count, whereby said first counter counts only the pulses representing the extant carrier load.

23. A loading vehicle and associated weighing system for measured delivery of bulk material, comprising in combination

a loading vehicle comprising a frame;

a load carrier;

means for supporting said load carrier relative to said frame; and

at least one hydraulic lift cylinder for lifting and lowering said supporting means and said load carrier relative to said frame;

weighing means comprising a transducer operatively connected to said lift cylinder, for detecting instantaneous hydraulic pressure therein and for producing an electric analog signal responsive to the instantaneous hydraulic pressure;

said weighing means further comprising means for converting said analog signal to a frequency signal consisting of pulses generated at a frequency proportional to said analog signal; and

means for counting said pulses for a selected time interval to determine the load carried in said carrying means.

24. Apparatus as set forth in claim 23

coacting members mounted on said frame and said supporting means for indicating to the operator a preselected weigh position of said supporting means relative to said frame.

25. Apparatus as set forth in claim 23

said counting means comprising first and second counters for counting pulses generated by said converting means;

first gate means for passing said pulses from said converting means to said first and second counters for a selected time interval, whereby the counted pulses will be representative of the load carried in said carrying means;

second gate means connected between said first gate means and said first counter for passing said pulses to said first counter;

and start switch means connected to said second gate means for opening said second gate means to pass pulses to said first counter.

26. Apparatus as set forth in claim 25

automatic switching means for opening periodically said first gate means;

and automatic reset means associated with said second counter whereby said second counter will indicate repeatedly the instantaneous load carried in said carrying means.

27. Apparatus as set forth in claim 23

said counting means comprising a counter for counting pulses generated by said converting means, and gate means for passing said pulses from said converting means to said counter for a selected time interval, whereby the counted pulses will be representative of the load carried in said carrying means.

28. Apparatus as set forth in claim 27

a start switch coupled to said gate means for opening said gate means to pass said pulses for each load in said carrying means.

29. Apparatus as set forth in claim 28

means for indicating the instantaneous load carried in said carrying means.

30. Apparatus as set forth in claim 29

said means for indicating the instantaneous load carried in said carrying means comprising a second means for counting said pulses for a selected time interval;

and said second counting means including automatic reset means.