Patent Description:
Balers for making cylindrical (or "round") bales of agricultural crop material are well known and include types known as fixed chamber balers, which include a set of compression rollers that define a bale forming zone of fixed size, and variable chamber balers, in which a bale forming zone is defined by one or more flexible elongate compression elements, for example belts. In variable chamber balers the bale forming zone defined by the flexible elongate compression elements increases in size as the bale is formed within the bale chamber. For the sake of simplicity in the present document each flexible elongate compression element will be referred to as a "belt".

The present invention relates to a variable chamber baler.

Typically, a variable chamber baler includes a pick up mechanism that gathers cut agricultural crop material ("bale material") from the ground and feeds the material into the bale chamber. The bale chamber typically includes a set of belts that are arranged side by side and trained around a set of rolls. Bale material is fed into a bale forming zone and the belts are driven to form a cylindrical bale by rotating and compressing the bale material. As more crop material is fed into the bale chamber the bale grows and the bale forming zone defined by the belts increases in size to accommodate the expanding bale. When the bale has reached the desired size, feeding is stopped and the bale is bound by feeding a binding material (for example netting, film or twine) into the bale chamber and wrapping it around the circumference of the bale. After binding, a tailgate in the rear of the baler opens and the finished bale is ejected from the bale chamber.

It is known from <CIT> to provide a variable chamber belt baler with spring-loaded feelers that are pressed against the belts on the right and the left hand side of the bale chamber, so as to indicate to the driver the shape of the bale in the bale chamber.

In the prior art the belt tension is measured by pressing a roller sensor into a straight part of the belt, and the distance that the belt is pressed inward is sensed and used as a measure of the tension in the belt.

The comparison between the distances pressed inward of the belts on the left and right hand sides of the bale chamber indicates the difference of the belt tension and any differences in the filling of the bale chamber with bale material.

A disadvantage of this system is that the belt will be deformed by the pressure of the roller sensor and because of this deformation the straight running the belts can be influenced; the belt will run more to the right or left over the successive rollers which could lead to wear (e.g. if the belts run onto the side walls of the bale chamber) and pollution of the bale material as the gaps between two successive belts will increase.

In another known baler, one of the idler rollers is mounted on a spring suspension system, which allows the roller to move in response to the tension in the belts. Sensors are provided for measuring movement at both ends of the roller and the signals from these sensors are used to determine a difference in belt tension across the width of the bale chamber. This system also suffers from the disadvantage that movement of the suspended roller affects straight running of the belts, leading to belt wear and pollution of the crop material.

<CIT> describes a round baler having a bale compression chamber, a roller that interacts directly or indirectly with a bale, and a sensor for detecting the size of the bale.

It is an object of the present invention to provide a variable chamber baler and a method of baling that overcomes or mitigates one or more of the aforesaid disadvantages.

According to one aspect of the present invention there is provided a variable chamber baler as defined by the claims.

In an embodiment the variable chamber baler comprises:.

The baler is able to sense a difference in belt tension across the width of the bale chamber, caused for example by uneven filling of the bale chamber with bale material. This allows an operator to adjust operation of the baler to ensure even filling of the bale chamber. Alternatively, operation of the baler may be controlled automatically to ensure even filling of the bale chamber. This ensures that the bale has an even cylindrical shape. Because the belt tension is sensed using strain gauges the run of the belt is not affected, thus avoiding issues with wear of the belts and pollution of the bale material.

Optionally, the first and second support elements comprise rigid support elements. This prevents significant movement of the sensing roller at least at the ends thereof in response to changes in the tension in the belts. Preferably, the support elements are sufficiently rigid to ensure that any radial movement of the axis of the sensing roller in response to changes in the tension in the belts is less than <NUM>, preferably less than <NUM>, and more preferably less than <NUM>.

Optionally, the first and second support elements are connected to the first and second side walls or a frame or of the baler. Alternatively, the support elements may be connected to any other rigid part of the baler.

Optionally, the first and second ends of the sensing roller are connected to the first and second support elements through rotary bearings, allowing rotation of the sensing roller.

Optionally, the belt is deflected as it runs around the sensing roller through a deflection angle θ where θ≥<NUM>°, or θ≥<NUM>°, or θ≥ <NUM>°, or θ≥ <NUM>°. This ensures that a large radial resultant force is transferred to the sensing roller from the belt.

Optionally, the sensing roller comprises an idler roller. This ensures that vibrations and/or drive forces from a drive mechanism do not interfere with the strain signals from the strain sensors. Alternatively, however, the sensing roller may comprise a driven roller.

Optionally, the sensing roller is located in an upper part of the bale chamber. For example, it may be one of the rollers that are located in the upper part of the bale chamber.

Optionally, the sensing roller is the uppermost of a plurality of rollers around which the belt runs.

Optionally, the baler includes a pair of movable rollers located adjacent the bale forming zone that can move in response to changes in the size of the bale in the bale forming zone, and a fixed intermediate roller located away from the bale forming zone that guides the belt as it runs between the movable rollers, wherein the intermediate roller comprises the sensing roller. This arrangement makes it possible to sense an absolute belt tension value that depends at least partially on the belt tension required to rotate and form the bale in addition to a difference in belt tension across the width of the bale chamber.

Optionally, the baler includes a plurality of belts that define a bale forming zone within the bale chamber, wherein the belts are arranged side-by-side across the width of the bale chamber. Alternatively, the baler may include a single belt that extends across the width of the bale chamber.

Optionally, the plurality of belts include a first belt located adjacent the first side wall of the bale chamber and a second belt located adjacent the second side wall of the bale chamber, wherein the control device is configured to determine from the received strain signals a difference in belt tension of the first and second belts. Alternatively, if the baler includes a single belt, the control device may be configured to determine from the received strain signals a difference in belt tension at the edges of the belt.

Optionally, the control device is connected to a display device and is configured to provide via the display device an operational indication that is based on the determined difference in belt tension across the width of the bale chamber. The operational indication may indicate, for example, the amount of bale material in different parts of the bale, or it may indicate the corrective action that the operator needs to take to correct uneven filling of the bale chamber, for example steering to the left or to the right relative to a swath of bale material on the ground. This allows an operator to take appropriative corrective action if a significant difference in belt tension is detected.

Optionally, the control device is configured to control operation of the baler so as to reduce the determined difference in belt tension across the width of the bale chamber. This enables the baler to take appropriative corrective action automatically if a significant difference in belt tension is detected.

Optionally, the control device is configured to reduce the determined difference in belt tension across the width of the bale chamber by controlling one or more of the following baler functions:.

These baler function may involve, for example, diverting the bale material towards the side of the bale chamber where the belt tension is lower.

The baler further comprises a belt tensioner that is configured to adjust the belt tension, wherein the control device is configured to control operation of the belt tensioner. This allows the control device to conduct certain operations of the belt tensioner automatically.

The control device is configured to control operation of the belt tensioner so as to reduce the belt tension if the determined difference in belt tension across the width of the bale chamber exceeds a predetermined limit, and/or if a sum of the received strain signals exceeds a predetermined limit.

If an excessive difference in belt tension is detected the belt tensioner may be controlled automatically to reduce the belt tension.

If an excessive belt tension is detected the belt tensioner may be controlled automatically to reduce the belt tension, for example to avoid excessive power consumption when baling crop material with a high moisture content.

Optionally, the control device includes an operator interface that enables an operator to select one or more operating parameters of the control device, wherein said operating parameters include one or more of:.

According to another aspect of the invention there is provided a method of forming a bale in a variable chamber baler as defined by the claims.

In an embodiment the variable chamber baler comprises a bale chamber having a width defined by first and second side walls, at least one belt that defines a bale forming zone within the bale chamber, at least one roller over which the belt runs, said at least one roller comprising a sensing roller having first and second ends supported by respective first and second support elements; first and second strain gauges mounted respectively on the first and second support elements and configured to sense strain in the first and second support elements, and a control device that is connected to receive strain signals from the first and second strain gauges, the method comprising:.

Optionally, the method further comprises displaying via the display device the determined difference in belt tension across the width of the bale chamber.

Optionally, the method further comprises controlling operation of the baler so as to reduce the determined difference in belt tension across the width of the bale chamber.

Optionally, the method further comprises reducing the determined difference in belt tension across the width of the bale chamber by controlling one or more of the following baler functions:.

The control device determines from the received strain signals a difference in belt tension across the width of the bale chamber, and the control device controls operation of the belt tensioner so as to reduce the belt tension if: the determined difference in belt tension across the width of the bale chamber exceeds a predetermined limit, and/or a sum of the received strain signals exceeds a predetermined limit.

Optionally, the method further comprises sensing the belt tension a first belt located adjacent the first side wall and a second belt located adjacent the second side wall of the bale chamber, and determining a difference in belt tension of the first and second belts.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, wherein:.

<FIG> & <FIG> show the main components of two agricultural variable chamber round balers <NUM> that embody the invention. Although there are few minor differences between the balers, these differences do not affect the following description of the invention.

The baler <NUM> includes a frame <NUM> and a housing <NUM> having a tailgate <NUM> that can pivot open about a pivot <NUM> in the upper part of the housing <NUM> to release a bale <NUM>. The baler <NUM> is mounted on wheels <NUM> and has a drawbar <NUM> allowing it to be drawn by an agricultural vehicle such as a tractor (not shown). The baler <NUM> is configured to be driven from the power take off unit (not shown) of the tractor.

The baler <NUM> includes a bale chamber <NUM> within which a round (cylindrical) bale <NUM> of bale material, for example crop material, can be formed. A bale forming zone <NUM> is provided within the bale chamber <NUM>, the shape of the bale forming zone <NUM> being defined the side walls <NUM> of the housing <NUM> and by one or more endless belts <NUM> that pass around a set of rollers 20a, 20b. The bale chamber <NUM> has a width W defined by the separation of the side walls <NUM>. In the embodiment shown in the drawings the baler <NUM> includes a plurality of belts <NUM> that are arranged side-by-side across the width W of the bale chamber <NUM>.

At least one of the rollers is a drive roller 20a that is driven via the power take-off unit and drives the belts <NUM> causing them to rotate around the rollers 20a, 20b. The other rollers are undriven idler rollers 20b that rotate with the belts <NUM>.

Two of the idler rollers comprise a pair movable rollers 20b', which are mounted on a tensioning arm <NUM>. The movable rollers 20b' are located adjacent the bale forming zone <NUM> and can move to accommodate a change in the size of the bale <NUM> in the bale forming zone <NUM>. An intermediate roller <NUM> is located in the belt run between the movable rollers 20b'. The intermediate roller <NUM> is mounted in a fixed position relative to the frame <NUM> at a location away from the bale forming zone <NUM>. The intermediate roller <NUM> guides the belt <NUM> as it runs from the rear part of the bale chamber <NUM>, around the movable rollers 20b' and the intermediate roller <NUM>, and back to the front part of the bale chamber <NUM>.

A third idler roller 20b" is mounted on the tensioning arm <NUM> to take up any slack in the belts <NUM> as the arm <NUM> moves. The tensioning arm <NUM> can be pivoted about a pivot point <NUM> to accommodate an increase or decrease the size of the bale forming zone <NUM> defined by the belts <NUM> within the bale chamber <NUM>. For example, the arm <NUM> pivots upwards when the bale forming zone <NUM> increases in size, and the arm <NUM> pivots downwards when the bale forming zone <NUM> decreases in size. During a bale forming operation the tensioning arm <NUM> starts in a low position to provide a small bale forming zone <NUM> and pivots upwards as the bale grows to accommodate the increasing the size of the bale <NUM>.

A belt tensioner <NUM>, for example a hydraulic or electric actuator, is connected between the tensioning arm <NUM> and the frame <NUM> and is operable to adjust the pressure on the tensioning arm <NUM> and the tension in the belts <NUM>. The belt tensioner <NUM> can be controlled to adjust the degree of compression of the bale material and the density of the bale <NUM>.

Optionally, the bale chamber <NUM> may be defined in part by one or more press rollers <NUM> and a starter roller <NUM>, which do not engage the belts <NUM>. The press rollers <NUM> and the starter roller <NUM> are located on opposite sides of a feed opening <NUM> through which bale material <NUM> is fed into the bale chamber <NUM>. The press rollers <NUM> and the starter roller <NUM> are normally driven rollers.

The baler also includes a pick-up mechanism <NUM> for picking up bale material from the ground and feeding it into the bale chamber <NUM> along a feed path <NUM>. Optionally, a rotating cutter <NUM> may be provided to chop the bale material as it passes along the feed path <NUM>. Optionally, a diverter mechanism (not shown) may be provided for diverting the bale material towards the left or right side of the bale chamber <NUM>.

The bale material is circulated within the bale chamber <NUM> and compressed by the rotating belts <NUM> and the rollers 20a, 20b, <NUM>, <NUM> thereby forming a round bale <NUM>. When the bale <NUM> has been formed and has reached a desired diameter it is bound with a suitable binding material, typically twine, net or film, which may be fed into the bale chamber <NUM> from a binding device <NUM> between the lowermost idler roller 20b in the front part of the bale chamber <NUM> and the upper press roller <NUM>. The binding material is wrapped around the bale <NUM> and the bound bale is then ejected from the bale chamber <NUM> by opening the tailgate <NUM>.

All the aforesaid features are conventional and may for example be as described in <CIT>. These features will not therefore be described in further detail.

The set of rollers 20a, 20b includes at least one roller (a "sensing roller") <NUM> that is used for sensing the tension in the belts <NUM>. The sensing roller <NUM> is preferably an idler roller 20b, but it may alternatively be a driven roller 20a. Preferably the sensing roller <NUM> is one of the rollers 20a, 20b that is essential for the guiding the belt <NUM> according to the design of the baler, to avoid increasing the total number of rollers in the bale chamber <NUM>.

The sensing roller <NUM> is preferably located in an upper part of the baler for easy access. In the example shown in the drawings the sensing roller <NUM> is the uppermost of the idler rollers 20b. However, the sensing roller <NUM> may alternatively be another one of the rollers 20a, 20b. For example, in an alternative embodiment that is described below, the intermediate roller <NUM> comprises the sensing roller <NUM>.

As shown in more detail in <FIG>, the sensing roller <NUM> has first and second ends <NUM>, which are supported by respective first and second support elements <NUM>. In this embodiment each support element <NUM> comprises a steel bar, wherein a first end of the bar is attached via a rotary bearing <NUM> to the roller <NUM> and a second end of the bar <NUM> is attached to the frame <NUM> of the baler. Alternatively, the second end of the bar <NUM> may be attached to a side plate <NUM> or another rigid component of the baler. The support elements <NUM> may also take other forms.

Preferably, the support elements <NUM> are rigid and are configured to prevent significant movement of the sensing roller <NUM> (apart from rotary movement of the sensing roller <NUM>) in response to changes in the tension in the belts <NUM>. In practice, the support elements <NUM> will deform slightly in response to the tension in the belts <NUM>, but the resulting radial movement of the axis of the sensing roller <NUM> will not be significant: that is, it will not affect running of the belts <NUM> or operation of the baler. In practice, the support elements <NUM> are sufficiently rigid to ensure that any radial movement of the axis of the sensing roller <NUM> in response to changes in the tension in the belts <NUM> is less than <NUM>, preferably less than <NUM>, and more preferably less than <NUM>.

First and second strain gauges <NUM> are mounted respectively on the first and second support elements <NUM> and are configured to sense strain in the first and second support elements <NUM>. The strain gauges <NUM> may for example be electrical resistance strain gauges. Alternatively, other types of force sensor or strain sensor may be used. Preferably the strain gauges are positioned to sense a pressure force, so as to save space.

The sensing roller <NUM> is preferably selected to be a roller that deflects the run of the belt <NUM> through a relatively large angle, to increase the resultant radial force on the sensing roller <NUM>. In the example illustrated in <FIG>, a first belt portion 18a runs towards the sensing roller <NUM> and a second belt portion 18b runs away from the sensing pulley <NUM>. A deflection angle θ is defined between the running direction of the first belt portion 18a (as represented in <FIG> by the dashed line 18a') and the running direction of the second belt portion 18b (as represented by the dashed line 18b'). In this example the belt is deflected around the sensing roller <NUM> through a deflection angle θ of approximately <NUM>°. More generally, the deflection angle θ is preferably defined by one of the ranges θ≥<NUM>°, or preferably θ≥<NUM>°, or more preferably θ≥<NUM>°, or more preferably θ≥<NUM>°.

As shown in <FIG>, a control device <NUM> is connected to receive strain signals from the first and second strain gauges <NUM> via a signal line <NUM>. Alternatively, the strain signals may be transmitted to the control device <NUM> wirelessly. The control device <NUM> is configured to determine from the received strain signals a difference in belt tension across the width W of the bale chamber. The control device <NUM> may optionally be connected via one or more signal lines <NUM> or wirelessly to a display device <NUM>, and/or optionally to an operator interface <NUM> that allows an operator to control operation of the baler via the control device <NUM>. The control device <NUM>, and/or the display device <NUM>, and/or the operator interface <NUM> may optionally be located in the cab of a tractor or agricultural vehicle used to tow the baler <NUM>.

Any difference in the belt tension on the right and left hand sides of the bale chamber <NUM> is measured by sensing the force exerted on the sensing roller <NUM> by the belts <NUM>, through the support elements <NUM> on the left and right sides of the baler <NUM>. The rigid support elements <NUM> are connected between the sensing roller <NUM> and the frame of the baler, so that there is no significant displacement of the sensing roller <NUM>, which could influence the running of the belts <NUM>.

If the baler <NUM> uses a single belt <NUM> that extends across the full width W of the bale chamber <NUM> the control device <NUM> will sense a difference in the belt tension between the left and right edges of the belt <NUM>. Alternatively, if the baler <NUM> employs a plurality of belts that are spaced apart across the width W of the bale chamber <NUM> the control device <NUM> will sense a difference in the belt tension between the left- and right-hand belts.

The difference in belt tension may be displayed via the display device <NUM> to an operator of the baler, who can make adjustments to ensure even filling of the bale chamber <NUM>. For example, if the display shows that the belt tension is higher on the left side of the bale chamber, the operator can adjust the path of the baler relative a swath of bale material on the ground so that more bale material is fed into the right side of the bale chamber. This can be done either by steering the tractor to the left or by adjusting the position of the baler relative to the tractor using an adjustable drawbar or by steering the baler.

Alternatively, if the baler has a diverter device within the feed device, this can be adjusted to divert more bale material towards the right side of the bale chamber.

The operations described above may also be controlled automatically. In a fully robotic baler that does not require an operator, the display device <NUM> may be omitted.

The operations described above will generally ensure that the bale chamber is filled evenly with bale material, producing good, evenly-shaped cylindrical bales. However, if for any reason the operator fails to respond to a display showing a difference in belt tension across the bale chamber, or if the operator responds incorrectly to exacerbate the problem, the baler can be configured to intervene automatically if the difference in belt tension exceeds a predetermined value to prevent possible damage to the belts <NUM>. For example, the control device <NUM> may optionally be connected via a control line <NUM> or wirelessly to the belt tensioner <NUM>, and may be configured to send a control signal to the belt tensioner <NUM> if the difference in belt tension exceeds a predetermined value, causing the belt tensioner <NUM> to retract the tensioning arm <NUM>, thereby reducing the tension in the belts <NUM>.

Claim 1:
A variable chamber baler comprising:
• a bale chamber (<NUM>) having a width defined by first and second side walls (<NUM>);
• at least one belt (<NUM>) that defines a bale forming zone within the bale chamber, wherein bale material is rotated and compressed by the belt within the bale forming zone to form a bale;
• at least one roller (<NUM>) over which the belt runs, said at least one roller comprising a sensing roller having first and second ends supported by respective first and second support elements (<NUM>);
• a belt tensioner (<NUM>) that is configured to adjust the belt tension;
• first and second strain gauges (<NUM>) mounted respectively on the first and second support elements and configured to sense strain in the first and second support elements; and
• a control device (<NUM>) connected to receive strain signals from the first and second strain gauges;
characterised in that
the control device (<NUM>) is configured to determine from the received strain signals a difference in belt tension across the width of the bale chamber
and
the control device is configured to control operation of the belt tensioner (<NUM>) so as to reduce the belt tension if:
i. the determined difference in belt tension across the width of the bale chamber exceeds a predetermined limit, and/or
ii. a sum of the received strain signals exceeds a predetermined limit.