MISTIE DETECTION AND INDICATION

Abstract: A microprocessor-based control circuit (26) monitors mistie switches (32) provided for the knotter mechanism of a rectangular baler. Each knotter has a switch which is actuated a first time when the knotter cycles and a second time if the knotter ties a knot in a loop of twine around a bale. The control circuit controls a visual display (28) to give an operator a first indication if the knotter does not cycle and a second indication if it fails to tie the knot.

Description: This invention relates to apparatus for detecting and indicating incorrectly tied knots, hereinafter refered to as mistie detector. US-A-4,624,180 discloses a microprocessor-based control circuit for controlling a rectangular baler so that bales of crop material of uniform density are produced and this disclosure is incorporated herein by reference. It is conventional to provide rectangular balers with knotters, as illustrated in US-A-3,416,824. After sufficient crop material to form a bale has been compacted, knotters encircle the bale with a loop of twine, tie a knot in the loop, and cut the loop from the twine supply. A knotter station usually has several knotters, the exact number being determined by the size of the bales produced by the baler. Co-pending Application No. (based on US Serial No. 056075) discloses a mistie detector for detecting when a knotter fails and this disclosure is also incorporated herein by reference. However, the mistie detection switch disclosed in that application produces two output signals on each knotter cycle. One signal is produced each time a knotter cycle is initiated and another signal is produced at the time the knot is pulled from the knotter if the knotter properly tied a knot in the loop surrounding the bale. The present invention is defined in the appended claims and provides a plurality of knotter mistie detectors connected to a microprocessor-based control circuit which monitors the operation of, and controls, the rectangular baler. The microprocessor computes bale movement and if one or more mistie detectors have not been actuated by the time a bale moves a predetermined distance, the microprocessor controls a display on an operator's panel to indicate which knotter or knotters failed to tie a knot. Apparatus may be provided for distinguishing between two signals produced by a single electrical switch so that the output of the switch may be used to separately signal an operator that (1) a knotter has failed to cycle and (2) that a knotter mistied, i.e. failed to properly tie a loop of twine around a bale. The microprocessor-based control circuit may be responsive to the mistie detectors so as to indicate when a knotter fails to tie a knot and when the knotter fails to cycle. Knotter mistie detection apparatus in accordance with the present invention will now be disclosed in greater details, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a top view, partly in section, of a portion of a rectangular baler; Figure 2 is a block circuit diagram of a microprocessor-based control system for controlling a rectangular baler; Figure 3 is a flow diagram illustrating a portion of a microprocessor program; and Figures 4A and 4B comprise a circuit diagram illustrating the hardware emulated by the microprocessor in monitoring and detecting misties. Figure 1 is a top view, partly in section, of a rectangular baler for forming bales 10 of compact crop material and tying the bales with loops of twine 12. The baler includes a plunger 14, a bale casing 16, and opening 18. A crank mechanism (not shown) drives a pair of connecting rods 20 which are pivotally connected to the plunger 14 through a pair of bearings 22. As the crank mechanism is operated, the plunger 14 is reciprocated between the position shown in solid line which is its limit of travel rearwardly of the baler, and the position 14′ which is its limit of travel towards the front of the baler. While the plunger 14 is to the left of the opening 18, crop material is injected into the bale casing 16 through the opening. As the plunger moves from 14′ to 14 it compacts the crop material against crop material compacted on a previous stroke of the plunger, thus building up a bale 10. As explained in US-A-4,624,180, strain gauges 24 may be provided at bearings 22 to sense the force on the connecting rods (conrods) 20 and the outputs of the strain gauges may be sampled by a microprocessor-based control circuit 26. The microprocessor 26 then controls movable tension rails (not shown) to vary the cross-sectional area of the bale casing. This permits an operator to control the density of the bales by entering at an operator's panel 28 a value representing a desired density. When a complete bale has been formed, a knotter station is activated to tie knots in loops of twine 12 and cut the loops from the twine supplies. The knotter station includes a plurality of knotters, each for tying a loop of twine around each bale. Each knotter is provided with a mistie detector pine 30 as disclosed in the above-referenced co-pending application. Each of these pins is pivotally mounted so that it may swing in a horizontal plane. During normal knotter operation, the pins 30 are encircled by the loops of twine 12 which encircle bale 10. After bale 10 is tied, and as the plunger 14 compresses crop material against bale 10 to form a second bale, the bale 10 is pushed rearwardly of the baler (right in Figure 1). The pins 30 being within loops of twine 12, are engaged by the loops. At about the time the left-most edge of bale 10 is aligned with the pins, the loops begin pivoting the pins 30 until the loops slip over the ends of the pins. The pins 30 are linked to mechanisms which operate mistie switches 32 as the pins are pivoted. Obviously, if a knotter does not tie a knot then there is no loop to engage detector pin 30 for that knotter and the mistie switch associated with the pin is not actuated. Although not evident in Figures 1 and 2, but as explained in the co-pending application, each mistie switch is normally actuated each time the knotter mechanism is actuated, and is actuated a second time if the knotter associated with the switch fails to tie a knot in the loop 12. The outputs of the mistie detector switches disclosed in the co-pending application may be applied to a microprocessor-based control circuit, such as that disclosed in US-A-4,624,180 in order to control a display on the panel 28 and indicate to the operator any malfunction of the knotter station. The operator's panel 28 may be like that shown in US-A-4,624,180, and the portion of the panel relating to the present invention is illustrated in Figure 4A. It includes an LCD display for displaying a lighted border 29 if any mistie occurs, and a plurality of segmented digit displays for identifying by number which mistie switch or switches detected a mistie. When the microprocessor in the control circuit 26 is turned on it first goes through an Initialise routine for initialising various hardware and setting up initial conditions. As one of the steps, the processor 26, at step 100 (Figure 3), checks a stored indication of the baler model number and if the model has 5 knotters a flag INIT2A is set. A Logic Initialise Flag 1BB is cleared and a First Pass Flag (WTCH 2A) is set during the Initialise routine. After completion of the Initialise routine, the program enters a routine MAIN which it repeatedly executes. In accordance with the present invention a Bale Count Update Flag 211F is tested at step 102. If it is set a bale count, i.e. an indication of the number of bales tied, is incremented and flag 211F is cleared at step 104. If flag 211F is not set, then the program branches around step 104. Them First Pass Flag is cleared at step 106 near the end of the routine. At intervals of about 500 microseconds the MAIN routine is interrupted and a routine IRQT is executed during which the conrod load sensors 24 are sampled and analysed. If a peak of conrod loading is detected a routine LOOP is called. This routine performs several functions including computation of bale slip for the plunger stroke just completed. The microcode listing for the portions of the LOOP routine related to the present invention appears in Appendix A to this specification. The IRQT also calls a routine SCAN which samples various inputs such as the mistie switches and generates codes for updating the operator's panel. The SCAN routine jumps to a LOGIC routine where the microprocessor analyses the inputs and from the analysis sets flags to control the program and the operator's panel. The macro-code for generating the flags necessary for controlling the mistie detection and indication function is also set forth in Appendix A. Figures 4A and 4B illustrate the hardware equivalent of the analysis performed by the LOGIC routine. As shown in Figure 4A, a mistie switch 1AL is connected to the set input of a S/R register 1BL. The output of 1BL is connected to one input of a NOR 203A and one input of an OR 203B (Figure 4B). The output of NOR 203A is applied to the date input of a CD latch 210A. The output of latch 210A is applied through an OR 213A to a register 299A and an OR 214A (Figure 4B). When the register 299A is set it is sensed during the SCAN routine and that routine causes the numeral 1 to appear on the operator's panel 28 indicating that knotter 1 failed to tie a knot. The output of OR 213A acts through OR 214A (Figure 4B) and OR 215A to set register 299F. The output of this register is sensed during the SCAN routine to control the lighting of the border 29 on panel 28. The arrangement for the other mistie switches is the same as that for switch 1AL except that the circuit for the fifth mistie switch 1AK includes an AND 213F connected between OR 213E and register 299E, and a second AND 202C connected between register 1BG and OR 203B. The flag IN1T 2A is registered at 201A and the output of this register is applied to both ANDs 202C and 201A. As previously indicated, IN1T 2A is set if the baler has five knotters. If the flag is not set, ANDs 202C and 213F are blocked, thereby isolating the circuit for the fifth mistie switch. Figure 4B shows several flag latches which are set or reset by the 1BB flag which is set at step 100 of Figure 3. Flag latches 206A, 210H, 211F and 211K are rest to 0, while flag latches 211H and 211J are set to 1. In a normal cycle the mistie switches 32 all produced output signals to set latches 1BL-1BG (Figure 4A). The outputs of the latches pass through OR 203B and trigger a 0.75 sec. time delay on (TDON) 204A. The output of TDON 204A sets S/R latch 209A. The output of latch 209A passes through OR 215A to register 299F which is the flag for turning on the mistie border 29 when the display is updated. The output of latch 209A sets latches 206A, 210H, 211F, 211H and 211J. The flag latch 206A causes a down counter to be preset at LOOP 40 (see Appendix) with the current mistie detection distance. The flag is cleared when LOOP 40 determines that the bale has travelled the mistie detection distance. Flag latch 210H is sensed at LOOP 23 and causes the strokes/bale count and the slip/bale count to be updated. The slip/bale count is used in an adaptive control algorithm to derive the mistie detection distance, i.e. how far the bale must travel before the logic checks for a mistie. It is also used in another adaptive control algorithm to derive the knotter failure distance, i.e. how far the bale must travel before the logic declares a knotter failure. Flag latch 211F is sensed by the routine MAIN (Figure 3) to increment Bale Count, the number of bales tied. The routine clears 211F after the count is updated. Flag latch 211H causes the knotter failure distance to be present in LOOP 44 after which the flag latch is cleared. Flag latch 211J will not result in any changes provided a prior knotter failure has not occurred. When latch 209A is set it acts through OR 209D and NORs 203A-203F to apply logic 0 to latches 210A-210E thus preventing the setting of flags 299A-299E. This in turn prevents any of the mistie numerals from being displayed when the panel is updated. When latch 209A is set it pulses a single shot device 209B which provides a one-cycle delay. The output of the single shot device 209B acts through OR 209C to reset latches 210A-210E and 1BL-1BG. On the next mistie sensing cycle, the mistie switches 32 again set latches 1BL-1BG. A mistie results in the corresponding latch remaining reset. Flag latch 206A is cleared at LOOP 40 after the bale has travelled a distance equal to the mistie detection distance. Flag latch 206A then clears flag 209A and sets flag latch 211K through NOT 207A and single shot device 208A. Both inputs to OR 209D are low so one input of each of NORs 203A-203F is low. The other input of NORs 203A-203F reflect the mistie conditions as stored in 1BL-1BG. If there is a mistie the corresponding latch 1BL-1BG remains reset so the corresponding NOR 203A-203F applies a logic 1 to the corresponding latch 210A-210E. The mistie is clocked into the latch by the output of latch 206A acting through NOT 207A, single shot device 208A and OR 209C. Mistie latches 1BL-1BG are cleared at the same time the mistie indications are clocked into latches 210A-210E. If any of the mistie latches 210A-210E is/are set, the outputs of the set latches act through the ORs 213A-213E to set the registers 299A-299E. This causes the numerals in the display 28 corresponding to the failed knotter or knotters to be displayed when the display is updated. The border 29 is also displayed because a circuit extends from each of ORs 213A-213E to OR 214A (Figure 4B), and from OR 214A through OR 215A to the register 299F which controls the display border 29. An audible alarm is sounded for 3 seconds in case of a mistie. The output of OR 214A is applied through a single shot device 215B, OR 216A and 3-second single shot 217A to the audible alarm A. In the case where a knotter fails to cycle, the audible alarm A is sounded for three seconds and all of the numerals on the display are lit to indicate misties by all knotters. The bale length is constantly monitored and if the bale exceeds the knotter failure detection distance flag latch 211J is cleared in the LOOP routine. The output of latch 211J acts through NOT 212A, a single shot device 215C, OR 216A and a single shot device 217A to sound the alarm. The output of NOT 212A also acts through all of NORs 213A-213E to set all of registers 299A-299E. This causes all of the mistie numerals 1-5 to be energised when the display is updated.

Claims: An apparatus for detecting incorrectly tied knots, hereinafter refered to as mistie detection apparatus for a baler having a knotter station with a plurality of knotters, the mistie detection apparatus, characterised in that it comprises: a sensor switch (32) for each knotter operable to produce a first signal when a knotter cycles, and a second signal only if the associated knotter fails to tie a knot; an operator panel (28); and, a control circuit (26) responsive to the sensor switches (32) for displaying on the panel a first indication when any knotter fails to cycle, and a second indication if one of the knotters fails to tie a knot in a loop. Apparatus as claimed in claim 1, characterised in that the control circuit (26) includes means for determining movement of a bale and displaying the first indication when the movement of the bale is greater than a predetermined knotter failure detection distance. A baler incorporating knotter mistie detection apparatus according to claim 1 or 2. A knotter incorporating mistie detection apparatus according to claim 1 or 2.

Inventors: STROSSER, RICHARD P.
Applicants: FORD NEW HOLLAND, INC. (A DELAWARE CORP.)
Application year: 1988
Main classification: A01F15
IPC codes: A01F15