MISTIE DETECTOR AND INDICATOR SYSTEM

Abstract: A mistie detector for a knotter, the detector comprising a detector pin (54) which is tied within a loop of flexible material (44) being knotted, and switch means (46) operable by the detector pin (54) on success­ ful completion of a knot.

Description: The present invention relates to apparatus for detecting and indicating incorrectly tied knots, hereinafter referred to as a mistie detector for detecting the failure of a knotter to tie a knot in a loop of wrapping material extending around a bale of crop material, for example. Knotters are well known in the agricultural machinery art as exemplified by US-A-3,416,824 and 4,493,498. These devices are utilised on so-called square or rectangular balers to encircle a bale of crop material with a loop of flexible wrapping material such as twine, tie a knot in the wrapping material, and then cut it. Several knotters are usually provided on a given baler, the number being governed by the size of the bales formed by the baler. In the event of a knotter failure, the operator should be notified as quickly as possible so that operation of the baler may be stopped before the bale is ejected. This is particularly true in the case of large balers where the large volume of crop material in a broken bale makes it extremely difficult manually to retie the bale. To alleviate this problem, one device uses a series of indicator flags to indicate when a knotter mistie occurs. However, this system of flags is such that it does not indicate a knotter mistie if, for example, a tied knot hangs up on the billhook. Accordingly, an object of the present invention is to provide a knotter with a mistie detector which reliably detects any failure of a knotter mechanism to tie a knot in a loop of flexible material surrounding a bale of crop material. The present invention is defined in the appended claims and provides a baler having a knotter mechanism having a needle, a billhook and twine disc for tying a knot, and a twine finger, which pivots in a horizontal plane for delivering a section of twine to the billhook, is provided with an elongated detector pin mounted on the twine finger. The detector pin is mounted on a horizontal pivot so that as crop material is forced into the knotter station, and carries with it a section of twine extending across the path of crop travel, the twine pivots the detector pin in a generally vertical plane, without moving the twine finger, until the twine slips over the end of the pin. The knotter then ties a loop in the twine encircling the bale and the detector pin and cuts the knotted loop from the twine supply. As the tied bale is moved out of the knotter station the loop engages the detector pin thus pivoting the pin and the twine finger in a generally horizontal plane. This causes a spring biased linkage attached to the twine finger to actuate a switch. Upon further movement of the bale out of the knotter station, the loop of twine slips over the end of the detector pin and the bias spring returns the twine finger and detector pin to their starting position. In the event of a knotter failure, the switch is not activated and the output of the switch may be utilised as an indication of the failure. A baler embodying mistie detector for a knotter in accordance with the present invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which:- Figures 1-4 are schematic views illustrating the present invention in combination with a prior art knotter mechanism, the several views illustrating the relative positions of various elements during a cycle of operation, and wherein: Figure 1 is a top view illustrating movement of a twine finger as it delivers a twine section to a billhook; Figure 2 is a side view showing the twine needle at its upward extent of travel; Figure 3 is a side view showing a tied and cut loop of twine encircling a bale and a detector pin; Figure 4 is a top view illustrating movement of the twine finger and detector pin as a bale is moved out of the knotter station; and, Figure 5 is a side view taken along line A-A of Figure 1 illustrating the pivoting of the detector pin in a vertical plane. Figures 1-5 schematically illustrate the mistie detector of the present invention as associated with a prior art knotter such as that shown in US-A-3,416,824. In the following description the terms "right" and "left" are for reference purposes only and are determined as if standing at the rear of the baler facing the direction of travel. Although a baler may have a plurality of knotters aligned transversely of the baler, only one knotter is illustrated in Figures 1-5, it being understood that all knotters are the same as the one shown. Figure 1 is a top view of a knotter station showing a knotter mechanism comprising a knotter shaft 10 carrying a twine finger cam 12 acting against a cam follower bearing 14 to rotate a twine finger shaft 15 which drives the twine fingers of all of the knotters. Each knotter has a first lever arm 16 attached to shaft 15 and a second lever arm 18 mounted on shaft 15 but free to rotate relative thereto. A tension spring 20 is attached to lever arm 18 and to an anchor bracket 22 (Figure 2). A twine finger assembly 24 includes a twine finger link 26, a twine finger 28 and a twine finger pivot 30. The twine finger link 26 is pivotally attached at one end to lever arm 18 and at the other end an eyelet is provided which surrounds a pin 32 extending generally vertically from the twine finger 28. A casing 34 of the baler of which the knotters form part is provided with slots 36 at the top and bottom thereof through which needles 38 (Figure 2) normally positioned below the bottom of the casing, may respectively extend through the casing to a position above the casing. Each needle 38 cooperates with an associated billhook 40 and a twine disc 42 to tie a knot in a twine 44 with the twine surrounding a bale 58 as described in the aforementioned US-A-3,416,824. In accordance with one aspect of the present invention, the knotter mechanism is provided with a mistie detector comprising a mistie detector switch 46 (Figure 2) and a mistie detector pin assembly 48 (Figure 1). The switch 46 may take any one of several forms but an electrical switch such as a Hall effect switch is preferred. The mistie detection assembly 48 includes a pair of supports 50 supporting a shaft 52 which serves as a pivot permitting a mistie detector pin 54 to pivot in a generally vertical plane. The supports 50 extend upwardly from the upper surface of the twine finger 28 and a torsion spring 56 normally applies a light bias force to the pin 54 tending to rotate it downwardly as viewed in Figure 2. The pin 54 is elongated and preferably extends across the associated upper slot 36 in the bale casing. Figure 3 shows the knotter at that point in a cycle where a bale, partially shown at 58, has been encircled with twine 44, the twine knotted at 60 and cut by a knife (not shown). The twine needle 38 has been retracted to its home position beneath the bottom of the bale casing 34. The end section 44¹ of the twine supply is held by the twine disc 42 and extends downwardly through the slot 36 in the bale casing 34 to the needle 38 (not shown in Figure 3) which has been retracted below the bale casing. The tied bale 58 is moved rearwardly (i.e. to the right in Figure 3) and discharged from the baler. The baler plunger (not shown) begins forming a new bale by forcing crop material into the knotter station. On each stroke, the plunger moves from left to right in Figure 3, carrying in front of it crop material. The right-most limit of plunger travel is indicated by the line 59. As the new crop material is forced into the knotter station from the left, it strikes the section of twine 44¹ and is partially encircled by the twine as it moves to the position occupied by the previous bale 58. As is evident from Figure 1, this movement causes the section of twine 44¹ to engage the underside of mistie detector pin 54 tending to cam the pin upwardly against the force of the bias spring 56. The twine section 44¹ rides up and over the end of pin 54 without causing the twine finger 28 to rotate, after which the bias spring 56 pivots the pin from the position shown in phantom outline in Figure 5 to the position shown in solid lines. When the bale being formed at the knotter station has reached a predetermined length a clutch (not shown) is engaged so that the knotter shaft 10 is cycled one revolution. As shaft 10 rotates, a force is transmitted through the cam 12, cam follower bearing 14 and the twine finger shaft 15 to the lever arm 16. The lever arm 16 has an outwardly extending leg 17 which extends over the lever arm 18 so that the lever arm 18 is pivoted clockwise (Figure 2) through an angle of about 45° to the position shown in phantom outline. As the lever arm 18 is pivoted, it acts through the twine finger link 26 to pivot the twine finger 28 about pivot 30 to the position shown in phantom outline in Figure 1. The twine needle 38 has risen up through the bale casing 34 and the twine section 44² (Figure 2) must be moved against the billhook 40. This is accomplished by pivoting the twine finger 28 against the twine section 44². The rotation of the twine finger 28 also moves the mistie detector assembly 48 away from the slot 36 as best seen by the phantom outline in Figure 1. As the lever arm 18 is pivoted clockwise to rotate the twine finger 28, it actuates the switch 46. The output of the switch 46 at this time may be used to signal the operator that a tying cycle is in progress. As the shaft 15 rocks back to its initial position, the spring 20 moves lever arm 18 back to its initial position and, through the link 26, moves the twine finger assembly back to its initial position. The twine needle 38 is still raised as shown in Figure 2 and the device is ready to tie a knot using twine sections 44² and 44³. It will be noted that since the twine finger 28 has pivoted back to its initial position the mistie detector pin 54 is now underneath the twine. The knotter now ties a knot by rotating the billhook 40 through a single revolution as fully explained in US-A-3,416,824 and cuts the twine, giving the condition shown in Figure 3 with the twine 44 encircling the bale 58 and the mistie detector pin 54. As the newly-tied bale is moved to the right for discharge from the baler, the twine loop engages the pin 54 as illustrated in Figure 4. The force exerted on the pin 54 causes the twine finger 28 to pivot clockwise about the pivot 30 to the phantom outline position shown in Figure 4. As the twine finger 28 pivots, it acts through the link 26 to pivot the lever arm 18 clockwise from the solid-line to the phantom outline position shown in Figure 3. The movement of lever arm 18 again actuates the switch 46 and actuation of the switch at this time indicates that the twine was successfully tied. As the bale is moved further to the right (Figure 4), the loop of twine slips over the end of the pin 54, thus permitting the twine finger 28 to again return to its initial position. Returning to Figure 4, it is evident that if there is a mistie so that a knot 60 is not tied in twine 44, then the twine loop will not pivot the pin 54 and the twine finger 28. As a result, the switch 46 is not actuated and failure to actuate the switch at this time is an indication of a mistie. A similar indication will be given if, for example, a knot is tied correctly but the twine hangs on the billhook. While a preferred embodiment of the invention has been described in specific detail it will be understood that various modifications and substitutions may be made in the preferred embodiment without departing from the spirit and scope of the invention as defined as follows. For example, while the invention has been described in conjunction with a knotter for tying knots in twine, it will be understood that the invention may be practiced with knotters using other flexible elongated wrapping materials.

Claims: A baler having apparatus for detecting incorrectly tied knots of a knotter, hereinafter referred to as a mistie detector, the knotter having a needle (38) for delivering twine (44) to a twine disc (42) and a twine finger (28) for delivering the twine to a billhook (40), the billhook (40) cooperating with the twine disc (42) to tie a knot in a loop of the twine encircling a bale of material (58) at a knotter station, characterised in that the mistie detector comprises: an elongated detector pin (54); means (50) pivotally supporting the detector pin (54) on the twine finger (28) so that the detector pin (54) may pivot in a first plane when engaged by the twine (44) as material is moved into a knotter station; the knotter tying a knot in the twine with a loop encircling the bale and the detector pin; a pivot (32) about which the twine finger (28) may pivot in a second plane orthogonal to the first plan when a bale is moved out of the knotter station and the loop engages the detector pin (54); and, switch means (46) actuated by the twine finger. A baler as claimed in claim 1, characterised in that the detector pin (54) extends across a slot (36) in the upper side of a bale casing (34) and the needle (38) normally rests below the bale casing but is moved through the slot to deliver twine to the twine disc (42) which is located above the bale casing. A baler as claimed in claim 2, characterised in that it further comprises spring means (20) for biasing the detector pin (54) about the detector pin support means (50), the spring means (20) urging the pin (54) towards the slot (36). A baler according to any of the preceding claims, characterised in that drive means (15) are provided for the knotter and in that linkage means (14-18, 26) connect the drive means (15) to the twine finger (28). A baler according to any of the preceding claims, characterised in that the knotter station has a plurality of knotters, in that cowon drive means (15) are provided for simultaneously driving all the knotters, in that the support means (50) supports the detector pin (54) so that one end thereof extends across an associated upper slot in the bale casing, and in that a linkage (14-18,26) for each knotter connects the common drive means (15) to each of the twine fingers (28). A baler as claimed in claim 4 or 5, characterised in that the drive means comprises a twine shaft (15) and means (14) for rocking the twine shaft to and fro once for each cycle of the or each knotter. A baler as claimed in claim 6, characterised in that the linkage for each knotter includes a first lever means (16) affixed to the twine shaft (15), and a second lever means (18) pivotable about the twine shaft and attached to the twine finger (28). A baler as claimed in claim 7, characterised in that the first lever means (16) includes an arm (17) extending laterally thereof for engaging and driving the second lever means (18) as the twine shaft (15) is rocked in a first direction; and spring means (20) for urging the second lever means (18) towards the laterally extending arm (17), the switch means (46) for each knotter being actuated by the second lever means (18). A baler as claimed in claim 8, characterised in that as a tied bale (58) is moved out of the knotter station the loops formed in the twine (44) engage the associated detector pin (54) to pivot the twine finger (28) and the second lever means (18) against the action of the spring means (20).

Inventors: JACKSON, ROBERT E.
Applicants: FORD NEW HOLLAND, INC. (A DELAWARE CORP.)
Application year: 1988
Main classification: A01F15
IPC codes: A01F15