Patent Description:
Rectangular bales are able to maintain their shape by means of a series of parallel extending twine loops, provided lengthwise around the bales. Current large square balers are equipped with a plurality of twine tensioners each associated with a plurality of knotter assemblies to maintain proper tension on the twine to ensure each knotter assembly performs properly. The twine is drawn from suitable twine boxes. If the twine tensioner fails to maintain proper tension on the twine, the twine can be pulled out of the knotter assembly and a mis-tie occurs. A number of factors affect the tension on the twine. Sometimes twine gets tangled in the twine box restricting twine supply from the twine box_which makes it difficult or impossible for the baler to make knots. In extreme situations the tension in the twine is sufficient to cause bending of the baler needles and also to interfere with the other baler components which may become damaged as a result. Once the baler needles become bent, functioning of the knotter mechanism is significantly impaired causing operational downtime of the baler until repairs may be effected.

It is further a problem that an operator of the baler will not know there is a problem until the knot has been missed or damage to baler components has occurred.

It is an advantage of the present invention that it seeks to address these problems.

<CIT> discloses a twine tensioner arm position sensor arrangement having the features of the precharacterising portion of claim <NUM>.

According to a first aspect of the present invention, a baler twine tension measurement assembly comprises a displacement detector and elements defining a first twine path, the first twine path extending between a first location and a second location angularly displaceable with respect to the first location, the displacement detector being operable to generate a signal indicative of the angular displacement of the second location with respect to the first locationcharacterised in that the first location comprises a first pulley located at a first end of an elongate element and the second location comprises a second pulley located on the elongate element, spaced from the first pulley.

Preferably, the first twine path further extends between the second location and a third location spaced from the second location.

Preferably, the third location comprises a third pulley located on the elongate element, spaced from the first pulley and the second pulley.

Preferably the baler twine tension measurement assembly further comprises a biased armature guided by movement of the elongate element, the biased armature being connected to the displacement detector.

Preferably the displacement detector comprises a potentiometer.

Preferably the biased armature is biased towards a first position by a biasing element extending between a mounting position and a free end of the armature.

More preferably the biasing element is a helical spring.

Preferably the baler twine tension measurement assembly further comprises additional twine paths provided in parallel to the first twine path, each additional twine path extending between a first fixed location and an associated second displaceable location angularly displaceable with respect to the first fixed location, the displacement detector being operable to generate a signal indicative of the furthest angular displacement of any displaceable location.

According to a second aspect of the invention a twine tension control system comprises a twine tension measurement assembly in accordance with the first aspect of the present invention, a controller to receive the signal from the twine tension measurement assembly and a knife mechanism actuable in response to a predetermined displacement of the first location away from a first position.

This has as an advantage that should the or one of the second displaceable locations be moved to the predetermined position under the action of strand of twine in the twine path, the predetermined position representing a tension in a strand of twine corresponding to or exceeding a predetermined threshold, a knife element is actuated to cross the strand of twine thereby cutting the strand of twine and so avoiding damage to the knotter mechanism and its component parts by a tension in the twine exceeding this threshold level.

Preferably the bale twine tension measurement assembly further comprises a plurality of housings including guide channels, guide means aligned with the first location being adapted for movement with the guide channels.

More preferably, the bale twine tension measurement assembly further comprises second biasing means to bias the first location to the first position.

According to a third aspect of the invention, in a combination comprising an agricultural vehicle and a baler towed by the agricultural vehicle, the baler comprising a plurality of knotter assemblies, and one or more twine tension measurement assemblies according to the first aspect of the invention associated with one or more of the plurality of knotter assemblies.

Preferably, the combination further comprises a control unit, a memory in communication with the control unit, and a user terminal in communication with the control unit, the control unit being configured to receive the signals issued by each baler twine tension control assembly, to compare the signals against a predetermined set of values stored in the memory to determine a terminal signal to be sent the user terminal to cause the user terminal to signal the status of the twine tension measurement assembly that caused the terminal signal to be generated.

This has as an advantage that the operator can determine which twine path or set of twine paths may require remedial attention.

More preferably the control unit is configured to compare the signals against a predetermined set of values stored in the memory and in the event of one of the signals issued by each baler twine tension control assembly corresponding to a cut-off value, the control also causes a cut-off signal to be sent to cause operation of the baler to cease.

Preferably the user terminal signals which tension measurement apparatus caused the terminal signal to be generated by way of a visual and/or an audible indication.

Preferably, the control unit comprises a processor located on the baler. Alternatively the control unit comprises a processor on the baler in communication with a processor on the agricultural vehicle. Alternatively, the control unit comprises a processor located on the agricultural vehicle.

Reference to terms such as longitudinal and transverse are made with respect to a longitudinal vehicle axis which is parallel to a normal forward direction of travel. References to terms such as horizontal and vertical are made with respect to the apparatus being located on level, non-sloping ground.

With reference to <FIG>, a semi-schematic diagram of an agricultural baler system <NUM> is shown in which the invention may be employed while baling loose crop material <NUM> from the ground <NUM> into formed bales <NUM>. The baler system includes a towing vehicle <NUM> and a baler <NUM>. The towing vehicle <NUM> may include a cab <NUM> wherein an operator may be located, an engine <NUM> operable to move the towing vehicle, and a power take-off (PTO) <NUM> operable to transfer mechanical power from the engine <NUM> to the baler <NUM>. The baler <NUM> is hitched to the towing vehicle in any suitable manner, and power for operating the various mechanisms of the baler <NUM> may be supplied by the PTO of the towing vehicle <NUM>. One having ordinary skill in the art should appreciate in the context of the present disclosure that the example baler <NUM> is merely illustrative.

The baler <NUM> has a baling chamber <NUM> within which bales of crop material are formed. The baler is depicted as an "in-line" type of baler wherein the loose crop material <NUM> is picked up by a pickup assembly <NUM> and then loaded up into the baling chamber <NUM> by way of a stuffer chute assembly <NUM> including a charge forming stuffer chamber.

In the illustrated embodiment, the baler <NUM> is an "extrusion" type baler in which the bale discharge orifice at the rear of the baler <NUM> is generally smaller than upstream portions of the baling chamber <NUM> such that the orifice restricts the freedom of movement of a previous charge and provides back pressure against which a reciprocating plunger <NUM> can act within the baling chamber <NUM> to compress charges of crop materials to form the next bale. The dimensions of the discharge orifice and the squeeze pressure on the bales at the orifice are controlled by a compression mechanism as is understood by one skilled in the art.

The reciprocating plunger <NUM> presses newly introduced charges of crop material against a previously formed and tied bale to form a new bale. This action also causes both bales to intermittently advance toward a rear discharge orifice of the baler <NUM>. The completed bales <NUM> are tied with binding material, for example twine. Once tied, the bales are discharged from the rear end of the bale-forming chamber onto a discharge platform in the form of a chute <NUM>.

A user terminal <NUM> communicates with an electronic control unit <NUM>. The electronic control unit <NUM> is also be in electronic or other communication with various components and devices of the baler (and/or the towing vehicle). Conveniently such communication may be enabled by way of a suitable data communication network <NUM> such as one compliant with the ISOBUS standard (a network in conformance to ISO <NUM>). For example, the electronic control unit may be in electronic communication with various actuators, sensors, and other devices within (or outside of) the baler. The electronic control unit <NUM> may communicate with various other components (including other controllers) in various known ways, including wirelessly.

Various alternative locations for the electronic control unit may be utilized, including locations on the towing vehicle. It will be understood that one or more electronic control units may be employed and that the electronic control unit(s) <NUM> may be mounted at various locations on the towing vehicle, baler, or elsewhere. The electronic control unit(s) may be a hardware, software, or hardware and software computing device, and may be configured to execute various computational and control functionality with respect to the baler (or towing vehicle).

The electronic control unit <NUM> is also able to access a suitable memory <NUM>. The memory <NUM> may take any suitable form and is in electronic communication with the electronic control unit <NUM>. The memory <NUM> is adapted to store, in any suitable manner such as a database or look up table, reference values for a desired parameter.

The baler <NUM> is provided with a plurality of knotter assemblies. In use, in order to provide a strand of twine to each knotter assembly, a strand of twine is drawn from a supply roll provided in a twine box located to a side of the baler <NUM> through a plurality of twine guides provided in a frame of the baler <NUM> and through a final twine guide associated with a knotter assembly to a tensioner of the associated knotter assembly. As is known the baler comprises a plurality of knotter assemblies and some of the knotter assemblies are supplied with strands of twine from supply rolls located to a first side of the baler and the others are supplied with strands of twine from supply rolls located to a second side of the baler.

Each knotter assembly is configured to take strands of twine looped around a formed bale and bind the strands with two knots. During the bale knotting cycle of the baler, needles of each knotter assembly abruptly pull lengths of the twine from at least certain of the supply rolls in order to feed the twine to the knotter assembly. In extreme situations, the twine gets tangled in the twine box and the resulting tension in the strand of twine is sufficient to cause bending of the needles and also to interfere with the other baler components which may become damaged as a result.

By introducing a twine tension measurement assembly (<FIG>; <FIG>) in the path of each of the strands of twine, this problem can be addressed. While reference is made to a strand of twine, it will be understood that the invention is equally suitable for use with strands of other binding material. It will be recognised that in the discussion of the embodiments below that certain elements have been omitted from some of the Figures for reasons of clarity. As between the embodiments like reference numerals have been used to refer to like parts.

Referring first to <FIG>, a first embodiment of a baler twine tension measurement assembly <NUM> is shown. In <FIG> the baler twine tension measurement assembly <NUM> is shown in a first tension released position in which the elements of the baler twine tension measurement assembly <NUM> are in an initial position. A strand of twine <NUM> is shown extending through the twine tension measurement assembly <NUM>. The baler twine tension measurement assembly <NUM> comprises a number of elements mounted directly or indirectly to a mounting bracket <NUM>. The mounting bracket <NUM> comprises a generally planar front vertical portion with left and right hand side L-shaped flanges extending along either side of the generally planar front vertical portion. The mounting bracket <NUM> may conveniently be secured to part of the frame of the baler <NUM> by way of the left and right hand side flanges in any suitable manner.

The generally planar front vertical portion is provided with a number of keyhole shaped apertures <NUM>. As may best be seen in <FIG>, in the illustrated embodiments, each aperture <NUM> comprises an upper generally circular portion <NUM> above a linear vertically extending channel <NUM>. Vertically extending housings <NUM> are secured in any suitable manner to the mounting bracket <NUM> to each side of the vertically extending channel <NUM> of each aperture <NUM>. Preferably the vertically extending housings <NUM> comprise a plastics material. The upper ends of the housings <NUM> are generally coterminous with a lower region of the circular portions <NUM> of the adjacent apertures <NUM>. In the illustrated embodiments, four such housings <NUM> are shown.

Each of the housings <NUM> is provided with channels or guide tracks <NUM>. The guide tracks extend substantially vertically and are located in each of the left and right hand side walls of the housings <NUM>. Preferably, the guide tracks <NUM> extend through the side walls.

To each side of the aligned vertically extending housings <NUM> first and second support brackets <NUM>,<NUM> are provided secured to the mounting bracket <NUM> in any suitable manner.

As best seen in <FIG> and <FIG>, the first support bracket <NUM> comprises an inner support surface <NUM> and an outer support surface <NUM>. A potentiometer <NUM> is mounted on the outer support surface <NUM> such that a shaft of the potentiometer <NUM> extends through an opening in the outer support surface <NUM>.

The inner support surface <NUM> is provided with an opening, conveniently aligned with the opening in the outer support surface <NUM>.

The second support bracket <NUM> comprises a first support surface <NUM>. An opening in the first support surface <NUM> of the second support bracket <NUM> is aligned with the opening in the inner support surface <NUM> of the first support bracket <NUM>.

A guide element <NUM> is mounted between the first and second support brackets <NUM>,<NUM>. The guide element <NUM> comprises a cross member <NUM> having first and second ends. Each of the first and second ends is connected to a second end of an arm <NUM>,<NUM>. A first end of each arm <NUM>,<NUM> is provided with an outwardly directed stub <NUM>,<NUM>. At a first end of the guide element <NUM> the stub <NUM> extends through the opening in the second support surface <NUM> of the first support bracket <NUM> and is connected to the potentiometer shaft in any suitable manner between the first and second support surfaces <NUM>,<NUM> of the first support bracket <NUM>. At a second end of the guide element <NUM> the stub <NUM> extends through the opening in the support surface <NUM> of the second support bracket <NUM>. The respective stubs <NUM>,<NUM> are mounted for rotation in their respective openings. A first generally horizontal axis of rotation is defined extending through the openings in the first and second support brackets <NUM>,<NUM>. The potentiometer <NUM> generates a signal indicative of the angular displacement of the guide element <NUM>. This signal is received by the control unit <NUM>. Movement of the guide element <NUM> will cause the potentiometer shaft to rotate and so signals indicative of the changing angular position of the guide element <NUM> to be generated. It will be understood that the potentiometer may be substituted for other suitable apparatus for converting this angular movement into an electrical signal.

U-shaped brackets <NUM> are mounted between each pair of housings <NUM> (cf <FIG>). Each U-shaped bracket <NUM> comprises upwardly extending side limbs <NUM> to either side of a central lower cross limb <NUM>. The lower cross limb <NUM> of each U shaped bracket <NUM> is provided with an opening.

A pivotable elongate element <NUM> is provided between each pair of housings <NUM>. Each elongate element <NUM> is substantially similar such that only one will be described. In the first embodiment of <FIG>, each pivotable elongate element <NUM> comprises first and second side elements <NUM>,<NUM>. A first pulley or roller <NUM> is mounted at a first end of the pivotable elongate element <NUM>. The first pulley <NUM> is disposed on a second axis of rotation extending though the housings <NUM>. The second axis of rotation is located above and behind the first axis of rotation. The first pulley <NUM> is mounted between the upper ends of the side limbs <NUM> of the respective U-shaped bracket <NUM>.

Stops <NUM>,<NUM> are provided to each side of the U shaped bracket <NUM> in line with the first pulley <NUM>. Each stop <NUM>,<NUM> is preferably generally cylindrical in shape. The stops <NUM>,<NUM> and the first pulley <NUM> may conveniently be mounted on a common axle extending through the upper ends of the side limbs <NUM> of the U-Shaped bracket <NUM>. The stops <NUM>,<NUM> are adapted to be seated within the guide tracks <NUM> of the adjacent housings <NUM>. Preferably the housings <NUM> are formed of a polymeric material. The stops <NUM>,<NUM> are formed of any suitable material, for example a metal such as steel.

In a mid-region of each pivotable elongate element <NUM>, the pivotable elongate element <NUM> is also provided with a second rotatable pulley or roller <NUM>. To each side of the second rotatable pulley <NUM>, further first and second stops <NUM>,<NUM> are mounted. Each further stop <NUM>,<NUM> is preferably generally cylindrical in shape. The further stops <NUM>,<NUM> and the second pulley <NUM> may conveniently be mounted on a common axle.

An upper bracket <NUM> is shown to one side of the generally planar front vertical portion of the mounting bracket <NUM>. The upper bracket <NUM> provides a mounting point spaced from the generally planar front vertical portion of the mounting bracket <NUM>. Biasing means are provided between the mounting point and one end of the guide element <NUM> to bias the guide element <NUM> into a raised position. In the illustrated embodiment, a first biasing element comprises a helical spring <NUM> extending between the mounting point and one end of the cross member <NUM> of the guide element <NUM>. In an alternative, less preferred, embodiment (not shown) a second support bracket may be provided on the other side of the mounting bracket with a second helical spring extending between a corresponding mounting point and the other end of the cross member <NUM> of the guide element <NUM>.

The mounting bracket <NUM> is also provided at a lower end of the generally planar front vertical portion with a flange plate <NUM>. The flange plate <NUM> is substantially L-shaped with a first limb <NUM> secured to the mounting bracket and a second limb <NUM> extending outward substantially orthogonally thereto. The second limb <NUM> is provided with a plurality of openings. The openings in the flange plate <NUM> are aligned vertically with the openings in the lower cross limbs <NUM> of the U-shaped brackets <NUM>. A second biasing means is located between each set of flange plate and U-shaped bracket openings. The second biasing means urges the U-shaped bracket and so the first end of the pivotable elongate element <NUM> upwards. The second biasing means takes the form of a compression spring <NUM> forming part of a cable release mechanism <NUM>.

A lower bracket <NUM> is also secured to a lower portion of the generally planar front vertical portion of the mounting bracket <NUM>. The lower bracket <NUM> is substantially L-shaped with a first limb <NUM> secured to a surface of the mounting bracket <NUM> and a second limb <NUM> extending outward substantially orthogonally thereto and beneath the second limb <NUM> of the flange plate <NUM>. The second limb <NUM> of the lower bracket <NUM> is provided with a plurality of cutaway portions <NUM>, each of the cutaway portions <NUM> being substantially vertically aligned with one of the openings in the second limb <NUM> of the flange plate <NUM>. Each of the cutaway portions <NUM> serves as a mounting point for the respective cable release mechanism <NUM>.

Each cable release mechanism <NUM> extends between a knife mechanism <NUM> and the twine tension measurement assembly <NUM>. The cable of the cable release mechanism <NUM> extends through the second biasing means with an end of a cable (not shown) of the cable release located within a respective U-shaped bracket. The cable is attached to the lower cross limb <NUM> of each U-shaped bracket <NUM> by a nut on each side of the lower cross limb <NUM> so the lower cross limb <NUM> controls the position of the cable.

In <FIG>, a strand of twine <NUM> is shown extending through a twine path defined by elements of the twine tension measurement assembly <NUM>. The strand of twine <NUM> initially extends upwards through one of the apertures <NUM> in the generally planar front vertical portion of the mounting bracket <NUM> and over an upper surface of the first pulley <NUM> in one of the pivotable elongate elements <NUM>, before exiting the twine tension measurement assembly <NUM> around the second pulley <NUM> and proceeding onward to the knotter mechanism.

In <FIG>, in the absence of tension in the strand of twine <NUM>, the first biasing element holds the guide element <NUM> in a raised position. The cross member <NUM> of the guide element <NUM> thus holds the elongate elements <NUM> in a raised position.

In the low tension situation of <FIG>, it can be seen that the tension in the strand of twine <NUM> has pulled the second pulley <NUM> downward about the second axis of rotation, against the action of the first biasing element. This causes a lower surface of the elongate element <NUM> to push against the cross member <NUM> of the guide element <NUM> pivoting the guide element <NUM> about the first axis of rotation. This movement of the guide element <NUM> is reflected by the potentiometer generating a signal to the control unit indicative of the position of the guide element <NUM>. It will be seen that the position of the guide element <NUM> depends on the tension the strand of twine <NUM> and so position of the guide element <NUM> is a measure of the tension in strand of twine <NUM>.

In the high tension scenario of <FIG>, where the tension in the strand of twine <NUM> while greater than that in <FIG> remains below that requiring action to be taken to avert potential damage to the knotter mechanism, the tension in the strand of twine <NUM> has caused the elongate element <NUM> and so the guide element <NUM> to be pivoted almost to their full extent about their respective axes. As before, the position of the guide element <NUM> will be detected by the potentiometer <NUM> which will send a signal to the control unit indicative of the level of tension in the strand of twine <NUM>.

In the cut-off position illustrated in <FIG> the tension in the strand of twine <NUM> has caused the elongate element <NUM> and so the guide element <NUM> to be pivoted about their respective axes to their full extent. Further angular movement of the elongate element <NUM> is prevented by abutment of the further <NUM>,<NUM> stops on an outer surface of the adjacent housings <NUM>. Additional tension in the system of the twine tension measurement assembly <NUM> will cause the elongate element <NUM> to be shifted downwards. The stops <NUM>,<NUM> will be guided in the guide tracks <NUM> and the U-shaped bracket <NUM> displaced against the second biasing means. The movement of the lower cross limb <NUM> of the U-shaped bracket <NUM> displaces the cable of the cable release mechanism <NUM> thereby causing actuation of the knife mechanism <NUM> to cause severing of the strand of twine <NUM>.

It will be understood that the second biasing means will be chosen to ensure that downward shifting of the elongate element <NUM> to the cut-off position does not occur until an undesirable tension has arisen in the twine tension measurement assembly.

The signals from the potentiometer <NUM> are received by the control unit <NUM> (step <NUM>, <FIG>). These signals are compared against reference values held in the memory <NUM> (step <NUM>). The reference values represent values of the tension detected in the twine tension measurement assembly. The control unit <NUM> then sends a terminal signal to the user terminal <NUM> based upon the reference value corresponding to the potentiometer signals (step <NUM>).

The user terminal <NUM> receives the terminal signal and indicates the tension level in the relevant twine tension measurement assembly to the operator in any suitable manner, for example by way of a visual signal and/or an audible signal. The visual signal may, by way of example, take the form of an icon or series of icons displayed on the user terminal <NUM>. The audible signal may, by way of example, take the form of a tone or spoken message issuing from the user terminal <NUM>.

The user terminal <NUM> will indicate an elevated tension condition using different visual signals and/or different audible signals.

If the tension is sufficiently elevated to cause the strand of twine <NUM> to be cut, and as a result the tension is released in the twine tension measurement assembly, the guide element <NUM> will return to its initial position under the action of the spring <NUM>.

In a preferred embodiment, once the strand of twine <NUM> has been cut, the electronic control unit <NUM> on receipt of a potentiometer signal corresponding to a cut off condition (for example very high tension followed by no tension) may optionally also generate a signal to cause the operation of the baler <NUM> to cease (step <NUM>). For example a signal may be sent to disengage a clutch <NUM> located between the PTO <NUM> and the reciprocating plunger <NUM> thereby preventing further bale formation. A suitable signal may also be sent to the user terminal to alert the operator to this action being taken.

Only one strand of twine <NUM> is shown in <FIG>. In practice several strands of twine may extend through the twine control assembly, each stand passing through a respective aperture and around a respective elongate element as described above. Each elongate element may be adapted to pivot independently of the others.

It will be appreciated that in this embodiment, the signals to the operator from the user terminal will reflect the tension levels in a set of strands of twine and that one of the set of strands of twine has been cut without identifying the strand of twine that has been cut.

Alternatively the elongate elements may be coupled together as a set. In this case, the highest tensioned strand will cause the set of elongate elements to move together against the guide element. The individual cable releases will be released together when the guide element is rotated to a position in which the stops of the elongate elements are displaced within the guide tracks <NUM> to cause cutting of the strands of twine. As before the signals to the operator will reflect the tension levels in a set of strands of twine and that a set of strands of twine have been cut.

In a second embodiment of the present invention shown in <FIG>, the pivotable elongate elements <NUM> are provided at a second end with a third pulley <NUM>. The third pulley <NUM> need not be rotatable and is mounted between the side elements <NUM>,<NUM> of each pivotable elongate element <NUM>. Further stops <NUM>,<NUM> may be provided. Each further stop <NUM>,<NUM> is preferably generally cylindrical in shape. The further stops <NUM>,<NUM> and the third pulley <NUM> may conveniently be mounted on a common axle.

In some circumstances a strand of twine comprises first and second portions of twine joined by a knot, for example when twine from sequential twine bales are joined. Sometimes the size of the knot will cause problems in the knotter mechanism. It is an advantage of this second embodiment that it prevents such knots from reaching the knotter mechanism.

Claim 1:
A baler twine tension measurement assembly (<NUM>) comprising a displacement detector (<NUM>) and elements defining a first twine path, the first twine path extending between a first location and a second location angularly displaceable with respect to the first location, the displacement detector being operable to generate a signal indicative of the angular displacement of the second location with respect to the first location characterised in that the first location comprises a first pulley (<NUM>) located at a first end of an elongate element (<NUM>) and the second location comprises a second pulley (<NUM>) located on the elongate element (<NUM>), spaced from the first pulley (<NUM>).