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 baler components may become damaged as a result. This is clearly a problem.

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.

It is known to provide a twine tension device ahead of the knotter assemblies in order to maintain tension in the twine, and such twine tensioning devices can comprise a pair of peripherally ribbed rollers as shown in <CIT>. However, such twine tension devices do not allow detection of excessive tension in the twine.

According to a first aspect of the present invention, a twine tensioner arrangement for a baler comprises a pair of rollers, each of the rollers being rotatable about a shaft and having circumferential lobes engaging each other in a meshing arrangement, characterised by at least one of the shafts being mounted on a displaceable armature, and the arrangement further comprising displacement measurement apparatus to measure the displacement of the displaceable armature and a signalling apparatus to generate a signal if the displacement of the displaceable armature exceeds a predetermined value.

This has as an advantage that a tension in a strand of twine entering the twine tensioner arrangement can be monitored and action taken to avoid a mistie or damage to the baler components.

Preferably the signalling apparatus generates the signal if the displacement of the armature exceeds a predetermined value for a predetermined period of time.

This has as an advantage that the signalling apparatus does not generate a signal where a brief increase in twine tension may be present, for example in the event of a momentary spike in twine tension required to work out a "natural memory" near tangle condition which works itself out as a strand of twine flows through the twine tensioner arrangement or generate a signal, for example, where passage of a knot joining two balls of twine will cause displacement of the displaceable armature without there being an increase in twine tension.

Preferably the signalling apparatus further comprises a control unit in communication with the displacement measurement apparatus and a user terminal, the control unit being adapted to receive signals from the displacement measurement apparatus, determine whether the signals from the displacement measurement apparatus represent displacement of the displaceable armature in excess of a predetermined value and if the signals from the displacement measurement apparatus represent displacement of the displaceable armature in excess of a predetermined value to generate a signal to the user terminal.

Alternatively or additionally, if the signals from the displacement measurement apparatus represent displacement of the displaceable armature in excess of a predetermined value the control unit additionally generates a signal causing operation of the baler to cease.

According to a second 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 knotters, each knotter having a twine tensioner arrangement according to the first aspect of the invention, the combination further comprising a user terminal associated with the agricultural vehicle, a control unit and a memory in communication with the control unit, the control unit being configured to receive a plurality of signals including the displacement signals representative of the displacement of the at least one shaft in each twine tensioner arrangement and to compare the displacement 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 and send a signal to the user terminal to a cause an indication of the error condition to be generated by the user terminal.

Alternatively or additionally, if the signals from the displacement measurement apparatus represent displacement of at least one displaceable shaft in excess of a predetermined value the control unit can also generate a signal causing operation of the baler to cease.

Preferably the indication of the error condition to be generated by the user terminal is a visual and/or an audible indication.

According to a third aspect of the invention, a method of monitoring twine tension in a baler and alerting a baler operator in the event of an error condition comprises the steps of a control unit receiving a plurality of signals, the signals representing a displacement of at least one shaft in each twine tensioner arrangement according to the first aspect of the invention, the control unit receiving a plurality of signals including the displacement signals representative of the displacement of the at least one shaft in each twine tensioner arrangement and comparing the displacement signals against a predetermined set of values stored in a memory to determine whether an error condition exists and in the event of an error condition the control unit generating and sending a signal to a user terminal to a cause an indication of the error condition to be generated by the user terminal.

Preferably, if the signals from the displacement measurement apparatus represent displacement of the at least one shaft in excess of a predetermined value the control unit can also generating a signal causing operation of the baler to cease.

According to a fourth aspect of the present invention, a computer readable program comprises instructions that cause the combination of the second aspect of the invention to implement the method of the third aspect of the invention.

A baler is provided with a plurality of knotter assemblies. In use, in order to provide twine to each knotter assembly, a strand of twine is drawn from a supply roll provided in a twine box located to the side of the baler through a plurality of twine guides provided in side plates of the baler and through a final twine guide associated with a twine tensioner assembly before entering the twine tensioner assembly. Each knotter assembly is provided with its own associated twine tensioner assembly. The twine then passes from the twine tensioner assembly to a tensioner arm of the associated knotter assembly.

Referring to <FIG>, each twine tensioner assembly <NUM> includes a twine tensioner or gripper including upper and lower rollers <NUM> and <NUM>, respectively. Each of the rollers <NUM>,<NUM> is adapted to rotate about a central shaft <NUM>,<NUM> and is provided with circumferential ridges, ribs or lobes <NUM>,<NUM>. In the illustrated embodiment the central shaft <NUM> of the upper roller <NUM> is offset vertically and horizontally with respect to the central shaft <NUM> of the lower roller <NUM>. It will be understood that other arrangements of the upper and lower rollers are possible.

In <FIG>, the ribs or lobes <NUM> of the lower roller <NUM> are in a meshed arrangement with ribs or lobes <NUM> of the upper roller <NUM>. The rollers <NUM> and <NUM> are biased together so as to maintain a tension in a length of twine being pulled through a nip of the meshed rollers <NUM>,<NUM>.

The rollers <NUM> and <NUM> may be biased together in any suitable manner.

Conveniently, a spring assembly <NUM> is used to bias the rollers <NUM>, <NUM> together. For example, the central shaft <NUM> of the upper roller <NUM> may be supported on a spring biased element, such as a spring biased armature.

When a strand of twine <NUM> is flowing freely into the twine tensioner assembly <NUM>, the tension in the strand of twine <NUM> is low and the strand of twine <NUM> is easily deformed between the lobes <NUM>,<NUM> of the rollers <NUM>,<NUM> (as in <FIG>).

However, if (as shown in <FIG>) the strand of twine <NUM> becomes snagged, knotted or otherwise fails to flow freely into the twine tensioner assembly <NUM>, the tension in the strand of twine <NUM> increases such that the strand of twine <NUM> is deformed significantly less by the roller lobes <NUM>,<NUM> and the tension causes the upper roller <NUM> to be displaced against the action of the spring assembly <NUM>, for example by the armature being displaced around a pivot point (not shown).

This displacement may be measured, for example by suitable measuring device capable of generating a measurement signal, for example a potentiometer <NUM> provided on a frame <NUM> of the twine tensioner assembly <NUM>.

The measurement signal is communicated to an electronic control unit <NUM>. The electronic control unit <NUM> is in communication with a user terminal <NUM>. The user terminal <NUM> is conveniently located in the driver's cab of an agricultural vehicle towing the baler.

Conveniently communication occurs by way of a suitable data communication network <NUM> such as one compliant with the ISOBUS standard (a network in conformance to ISO <NUM>).

The control unit <NUM> may conveniently comprise a single processor located on the agricultural vehicle towing the baler or its functions may be split between a processor located on the agricultural vehicle and one or more additional processors located on the baler, the additional processor(s) being in electronic communication with the first processor.

The 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 control unit <NUM>. The memory <NUM> is adapted to store, in any suitable manner such as a database or look up table, reference values relating to the measurement signal.

In operation, the control unit receives measurement signals from the measuring device, in the illustrated embodiment, the potentiometer (step <NUM>, <FIG>). The measurement signals are compared to the reference values in the memory (step <NUM>). The control unit determines if an error condition is present (step <NUM>). Such an error condition may correspond to a measurement signal in excess of a predetermined value or a series of measurement signals exceeding a predetermined value over a predetermined time interval. In the event of an error condition being determined, a signal is sent by the control unit <NUM> to the user terminal to alert an operator of the baler of the existence of an error condition (step <NUM>). In the absence of an error condition being determined no signal is sent.

In a preferred embodiment, the control unit <NUM> also generates a signal to cause the operation of the baler to cease, preferably if the measurement signal is significantly greater than that required for the initial notification of an error condition.

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. Since each twine tensioner arrangement is monitored, the signal from the control unit <NUM> to the user terminal <NUM> can indicate which twine tensioner assembly <NUM> has caused the signal to be generated, thereby enabling the operator quickly to identify the location of the problem and so address the cause of the problem.

Claim 1:
A twine tensioner arrangement (<NUM>) for a baler comprises a pair of rollers (<NUM>,<NUM>), each of the rollers (<NUM>,<NUM>) being rotatable about a shaft (<NUM>,<NUM>) and having circumferential lobes (<NUM>,<NUM>), characterised by at least one of the shafts (<NUM>) being mounted on a displaceable armature, and the arrangement further comprising a displacement measurement apparatus (<NUM>) to measure the displacement of the displaceable armature and a signalling apparatus to generate a signal if the displacement of the displaceable armature exceeds a predetermined value.