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 pivotally mounted, upwardly biased twine tensioner arms 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 arm fails to maintain proper tension on the twine, the twine can be pulled out of the knotter assembly and a mistie occurs. A number of factors affect the tension on the twine. Sometimes twine gets tangled in 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.

Problems of twine detection also arise in other areas such as guiding a thread from a thread store to a knitting machine (disclosed in <CIT>) and when winding yarn onto a liner (disclosed in <CIT>). In both instances maintaining an even tension during processing of the thread and yarn is important, but in both cases the problem addressed is that in a high tension condition the thread or yarn becomes broken, rather than that the high tension condition will lead to damage to the machinery concerned.

According to a first aspect of the present invention, a twine tension relief assembly for a baler comprises a tension detection apparatus for detecting the tension in a line of twine, a biased cutting element comprising a displaceable knife element and a compression spring, the biased cutting element being displaceable between a first retained position and a second released position, a displaceable release mechanism and an actuator adapted to release the biased cutting element from the first retained position and allow the biased cutting element to move to the second released position in response to a signal issued by the tension detection apparatus, characterised in that the knife element comprises a keyhole aperture comprising a circular opening and an elongate channel extending along a longitudinal axis of the knife element.

This has as an advantage that should a tension in a strand of twine exceed a predetermined threshold, the tension detection apparatus generates the signal to cause the movement of the biased cutting element so that a strand of twine passing though the twine tension relief assembly is severed and damage to the knotter mechanism and its component parts is avoided.

Preferably, the twine tension relief assembly further comprises a housing having a channel in which the biased cutting element is located.

More preferably, the displaceable release mechanism comprises a rotational body rotatable about an axis between a first position or set of positions in which the biased cutting element is maintained in the first retained position and a second position in which the biased cutting element is free to advance to the second released position.

Even more preferably, the rotational body extends through the keyhole aperture, and comprises a linear portion in the region of the keyhole aperture, the linear portion adopting a first configuration displaced from the elongate channel when the biased cutting element is in the first retained position and a second configuration aligned with the elongate channel when the biased cutting element is in the second released position.

Yet more preferably, the rotational body comprises a lever operated by the actuator to cause the rotational body to rotate the linear portion from the first configuration to the second configuration.

According to a second aspect of the invention, a combination comprising an agricultural vehicle and a baler towed by the agricultural vehicle, wherein the baler comprising a plurality of knotter assemblies, each knotter assembly being provided with an associated twine tension relief assembly according to the first aspect of the invention.

Preferably, the combination further comprises a control unit and a memory in communication with the control unit, the control unit being configured to receive the signals issued by each tension detection apparatus and to compare the signals against a predetermined set of values stored in the memory to determine whether an error condition exists and in the event of an error condition the control unit being configured to generate a signal to operate the actuator associated with the tension detection apparatus generating the signal corresponding to the error condition.

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.

Preferably the agricultural vehicle comprises a user terminal in communication with the control unit. More preferably, in the event of an error condition the control unit being configured to generate a signal to cause the user terminal to signal which tension detection apparatus generated the signal corresponding to the error condition. This has as an advantage that the operator can determine which twine path requires remedial attention.

Preferably, in the event of an error condition the control unit is adapted to generate a signal to cause the baler to cease operating.

Reference to terms such as longitudinal, transverse and vertical are made with respect to a longitudinal vehicle axis which is parallel to a normal forward direction of travel.

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 binding material to each knotter assembly, a strand of binding material <NUM> 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 arm 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 binding material from supply rolls located to one side of the baler and the others are supplied with strands of binding material from supply rolls located to one side of the baler.

Each knotter assembly is configured to take strands of the binding material looped around a formed bale and bind the strands with two knots. During the bale knotting cycle of the baler, needles of each knotter mechanism abruptly pull lengths of the binding material from at least certain of the supply rolls in order to feed the binding material to the knotter mechanism. In extreme situations, the binding material gets tangled in the twine box and the resulting tension in the strand of binding material 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 relief assembly (<FIG>) in the path of each of the strands of binding material, this problem can be addressed.

Referring to <FIG>, an example twine tension relief assembly <NUM> in accordance with the present invention is shown in which the strand <NUM> of binding material or twine is running freely. It will be understood that similar twine tension relief assemblies corresponding to the example twine tension relief assembly can be provided for each strand of twine. A suitable tension detection apparatus <NUM> for detecting the tension in the strand of twine <NUM> is provided. The tension detection apparatus <NUM> is in electronic communication with the electronic control unit <NUM>. Again, it will be understood that any similar twine tension relief assemblies will each be provided with a suitable tension detection apparatus.

The example twine tension relief assembly <NUM> further comprises a biased cutting element and an actuator mechanism adapted to release the biased cutting element in response to a signal issued by the tension detection apparatus <NUM>. In practice, the electronic control unit <NUM> is configured to receive signals issued by the tension detection apparatus <NUM> and to compare the signals against a predetermined set of values stored in the memory <NUM> to determine whether an error condition exists and in the event of an error condition the electronic control unit <NUM> is configured to generate an instruction signal to operate the actuator mechanism to release the biased cutting element.

This has as an advantage that should a tension in a strand of twine exceed a predetermined threshold, the biased cutting element may be released so that the strand of twine is severed and damage to the knotter mechanism and its component parts is avoided.

The biased cutting element is located within a channel in a housing. In the illustrated embodiment the housing comprises three principal elements; upper and lower central housing elements <NUM>, <NUM> and first and second side housing elements <NUM>,<NUM>.

Each of the first and second side housing elements <NUM>,<NUM> are generally planar and include matching elongate windows <NUM>. Each of the first and second side housing elements <NUM>,<NUM> is also provided with an opening through which the strand <NUM> of twine may pass. In the illustrated embodiment, the twine relief assembly is further provided with a tubular guard member: a first part <NUM> extending away from the opening in the first side housing element <NUM> and a second part <NUM> extending away from the opening in the second side housing element <NUM>.

As can be seen from <FIG>, the upper and lower central housing elements <NUM>, <NUM> are secured between the first and second side housing elements <NUM>,<NUM>. The upper and lower central housing elements <NUM>, <NUM> and the first and second side housing elements <NUM>,<NUM> may be secured together in any convenient manner, for example by way of suitable fastenings.

The upper and lower central housing elements <NUM>, <NUM> are generally planar and together provide a central channel extending between these elements. The central channel comprises a first relatively broader portion <NUM> through which in use the strand of twine may pass, and a second narrower portion <NUM> extending back from the first relatively broader portion <NUM>. It can be seen that a first shoulder portion <NUM> connects the first relatively broader portion <NUM> and the second narrower portion <NUM>.

A knife element <NUM> is housed within the central channel. The knife element <NUM> comprises a first broader portion <NUM> including a cutting edge and a second narrower portion <NUM> extending to the rear of the first broader portion <NUM>. A shoulder portion <NUM> connects the first broader portion <NUM> and the second narrower portion <NUM>. The first broader portion <NUM> is provided with a keyhole aperture (shown in more detail in <FIG>) comprising a circular opening <NUM> at one end with an elongate channel <NUM> extending away from the circular opening <NUM> along a longitudinal axis of the knife element <NUM>.

The first broader portion <NUM> of the knife element <NUM> is adapted to be located within the first broader portion <NUM> of the central channel of the central housing element. The second narrower portion <NUM> of the knife element extends back within the narrower portion <NUM> of the central channel.

A support bracket <NUM> is secured, in any suitable manner, to the one of the side housing elements, in the illustrated embodiment, the second side housing element <NUM>. In the illustrated embodiment fasteners are used. A biasing element is provided to urge the knife element forwards out of the central channel. In the illustrated embodiment, the biasing element comprises a compression spring <NUM>. The compression spring <NUM> is secured at a first end in any suitable manner at a fixed point of the twine relief assembly <NUM>, for example to a rear of the central channel of the central housing element or to a suitable point on the support bracket <NUM>. In use, the compression spring <NUM> extends around the narrower portion <NUM> of the knife element <NUM> and a second end of the compression spring <NUM> abuts the shoulder portion <NUM> of the knife element <NUM>. It can be seen that a substantial portion of the compression spring <NUM> extends within the narrower portion <NUM> of the central channel.

A guide pin <NUM> connects the first and second side housing members and extends through the elongate channel <NUM> of the keyhole aperture of the knife element <NUM>.

A locking device comprises a substantially cylindrical rotational body <NUM> extending through the first and second side housing elements <NUM>,<NUM>. In the illustrated embodiment it can be seen that a portion of the rotational body <NUM> extends to the side of the second side housing element <NUM>, where a first end of the rotational body <NUM> is fixedly attached to a first end of a lever arm <NUM>. The lever arm <NUM> extends orthogonally away from the rotational body <NUM>. The rotational body <NUM> is provided with two diametrically opposed cut away portions where the rotational body <NUM> extends though the knife element <NUM> to form a central linear portion <NUM> extending across the rotational body <NUM>. In practice these cut away portions coincide with the region of the elongate channel <NUM> and so the knife element <NUM>.

When the knife element <NUM> is in the first retained position, the central linear portion <NUM> is located within the circular opening <NUM> of the keyhole aperture, but is not aligned with the elongate channel <NUM> of that aperture. As such, the knife element <NUM> is held by the rotational body <NUM> against the force of the compression spring <NUM>.

A second end of the lever arm <NUM> is housed within a yoke <NUM> of a joint. The free end of the joint is connected to a piston rod <NUM> controlled by an actuator <NUM>.

In operation, the electronic control unit <NUM> receives measurement signals from the twine tension detector <NUM>, for example from a potentiometer (step <NUM>, <FIG>). The measurement signals are compared to the reference values in the memory (step <NUM>). The electronic control unit <NUM> determines if an error condition is present (step <NUM>). Such an error condition may correspond to a measurement signal in excess of a predetermined reference value or a series of measurement signals exceeding a predetermined reference value over a predetermined time interval. In the event of an error condition being determined, a signal is sent by the electronic control unit <NUM> to the relevant actuator <NUM> associated with the twine tension detector <NUM> issuing the measurement signal determined to have represented an error condition (step <NUM>).

The actuator <NUM> causes the piston rod <NUM> to advance - to the left as shown in <FIG> - thereby causing the lever arm <NUM> to rotate - clockwise as shown in the Figures. This, in turn causes the rotational body <NUM> to rotate such that the linear portion <NUM> becomes aligned with the elongate channel <NUM> of the keyhole aperture. Once aligned the rotational body <NUM> no longer acts against the compression spring <NUM> and the compression spring now drives the knife element <NUM> forwards and the blade of the knife element <NUM> across the strand <NUM> of twine so that the strand <NUM> of twine is severed (<FIG>). It will be understood that severing of the strand <NUM> of twine will automatically relieve the tension in the strand <NUM> of twine in the region of the knotter mechanism thereby preventing damage to the needles or other parts of the baler.

The forward movement of the knife element <NUM> is stopped by the trailing end of the elongate channel <NUM> abutting the guide pin <NUM>. The compression spring <NUM> holds the knife element <NUM> against the guide pin <NUM> to maintain the biased cutting element in the second released position. It can be seen from <FIG> that in the second released position a rear end of the knife element <NUM> extends beyond the end of the narrower portion <NUM> of the channel. In the released position the blade of the knife element is retained between the first and second side elements <NUM>,<NUM> and does not project outwards beyond the housing of the twine tension relief assembly.

In the event of an error condition being determined, a signal is also sent by the electronic control unit <NUM> to the user terminal <NUM> to cause an operator of the baler <NUM> to be alerted to the existence of the error condition and the action taken to address the error condition (step <NUM>). The user terminal <NUM> may indicate the error condition 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 displayed on the user terminal. The audible signal may, by way of example, take the form of a tone or spoken message issuing from the user terminal. Since each twine relief assembly <NUM> is monitored, the signal from the control unit to the user terminal can indicate which twine relief assembly <NUM> has caused the signal to be generated, thereby enabling the operator quickly to identify the location of the problem and so take appropriate remedial action.

In the absence of an error condition being determined no signals are sent to the actuator or the user terminal (step <NUM>).

In a preferred embodiment, the electronic control unit <NUM> also generates a signal to cause the operation of the baler <NUM> to cease. 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. Again a suitable signal may be sent to the user terminal to alert the operator to this action being taken.

Appropriate remedial action may include untangling the strand of twine (or addressing another problem causing the tension in the strand of twine), and resetting the twine tension relief assembly by withdrawing the biased cutting element and rotating the rotational body back to the first configuration to hold the biased element in the first retained position before rethreading the strand of twine though the twine tension relief assembly to the associated knotter assembly to enable baling to continue.

Claim 1:
A twine tension relief assembly (<NUM>) for a baler (<NUM>) comprising a tension detection apparatus (<NUM>) for detecting the tension in a line of twine (<NUM>), a biased cutting element comprising a displaceable knife element (<NUM>) and a compression spring (<NUM>), the biased cutting element being displaceable between a first retained position and a second released position, characterised in that the twine tension assembly comprises a displaceable release mechanism arranged for being actuated by an actuator (<NUM>) adapted to release the biased cutting element from the first retained position and allow the biased cutting element to move to the second released position in response to a signal issued by the tension detection apparatus (<NUM>), wherein the displaceable knife element (<NUM>) comprises a keyhole aperture comprising a circular opening (<NUM>) and an elongate channel (<NUM>) extending along a longitudinal axis of the displacebale knife element (<NUM>).