Patent Description:
Baling machines are well known in agriculture and are widely used to bale plant matter in fields into bales that may be conveniently and effectively handled, stored and used. Baling machines are known that bale forage products such as grass and other leaves used as hay or other types of animal feed; straw or other plant parts resulting as by-products from a harvesting operation such as combine harvesting; cotton; and other plant parts of commercial or other value.

The majority of baling machines in use in Europe are designed to be towed behind an agricultural tractor or another towing vehicle that, under the control of an operator and/or using operator-monitored software, moves the baling machine about a field and provides power to operate internal parts of the baling machine. The provision of power is effected by way of a rotatable power take-off (PTO) shaft connected to the rotary power take-off that typically is part of the tractor.

Known designs of agricultural baling machine include a pick-up, mounted at the front of the machine, that causes the ingestion of plant matter into the interior of the machine as it moves about a field. Differing internal designs of baler components are known in the part of the machine downstream of the pick-up.

One commonplace type of baling machine is often referred to as a "rectangular baler". This includes a cuboidal bale-forming chamber in which the ingested plant matter is compacted into a cuboidal shape by a piston or plunger that reciprocates longitudinally back and forth inside the bale-forming chamber between retracted and extended positions. Charges of plant matter repeatedly are fed into the bale-forming chamber from the pick-up by the mechanism of the baling machine. This action is timed with the motion of the plunger such that feeding of plant matter coincides with retraction of the plunger to one end of the bale-forming chamber. The plant matter then is compacted by subsequent extension strokes of the plunger along the bale-forming chamber.

The reciprocal rectilinear motion of the plunger is effected using a driveline that converts rotary drive derived from the rotating PTO shaft, connected to the baling machine above the pick-up, into reciprocal motion of the plunger. This typically is achieved by changing, in the driveline, the axis of the rotation from one parallel to the longitudinal length of the baling machine to an axis of rotation transverse thereto.

Such transverse-axis rotation is applied to a crank that is pivot-jointed to one end of a conrod the other end of which is pivot-jointed to the plunger, that is moveably captive inside the bale-forming chamber. As a result, rotation of the crank causes the reciprocal movement of the plunger.

The driveline between the power take-off of the tractor and the plunger includes a clutch that in a typical case is formed of two or more dry friction plates that are urged into mutual engagement by a hydraulic actuator or spring arrangement. Additionally a heavy flywheel (that in some baling machine designs weighs <NUM> or more) is secured to a rotatable shaft that defines or is connected to an input shaft in turn connected in use to the PTO shaft.

The flywheel is needed because the plunger during its motion is associated with very high, and highly varying, levels of power that might peak at <NUM> Hp (about <NUM> kW). In the absence of the flywheel it might be impossible for the rotary power take-off of a tractor to provide sufficient power to move the plunger, and very high forces might be transmitted back towards the tractor via the PTO shaft potentially causing damage to the baling machine or tractor or making the tractor-baling machine combination difficult to control.

The flywheel and the plunger present a system having a high level of inertia and, in some cases, mechanical resistance (especially when the driveline is at rest or is moving slowly). The inertia and mechanical resistance can be increased by factors such as:.

Often the output power of the tractor that is connected to tow and power the baling machine is poorly matched to the energy requirements of such a system. Furthermore, the power output of the tractor will likely not be accurately known. The tractor power can be an unknown/uncertain factor due to one or more of the following reasons: (i) the advertised power deviates from what its actually capable of delivering; and (ii) the torque an engine is able to deliver depends on its engine speed according to a torque curve - this curve is typically not known by the user. Tractor power can also depend on the temperature of the tractor engine. For example, if the baler is started up at the beginning of a day the temperature of the engine may be significantly less than when the engine is at temperature. Such factors lead to numerous practical problems.

In such a situation the energy of the PTO shaft may be insufficient to cause either movement of the plunger or slipping of the baling machine driveline clutch, with the result that on engagement of the power take-off the engine of the tractor stalls. This may cause damage to the power take-off components or in some cases the engine of the tractor. Even if these outcomes do not occur, the inevitable interruptions in the baling activity are undesirable because of their adverse effect on bale quality and integrity and the wasting of commercially valuable plant matter.

In view of the above, it will be appreciated that there is a need for improved balers and a method of controlling such a baler that will solve or ameliorate one or more problems of prior art baling machines.

The terms "baling machine" and "baler" are used synonymously herein and in the art generally.

The term "power take-off" is synonymous with the acronym "PTO".

The term "tractor" embraces a wide variety of work vehicles potentially capable of towing a baling machine, as will be known to the person of skill in the art.

The term "clutch" except as otherwise explained embraces any design of clutch that is suitable for transferring drive in the circumstances described.

The term "plant matter" and derivatives potentially includes all types of matter that potentially may be ingested into a baling machine for the purpose of being formed into bales.

The terms "piston" and "plunger" in the context of the principal, moveable, bale-forming part of a bale-forming chamber are used synonymously herein.

<CIT> discloses an agricultural system comprises a baler with a plunger and a sensor for sensing a plunger-related value; a vehicle comprising a power source operable to convey power to said plunger; a CVT arranged to drive the plunger. In order to balance a fluctuating load of the plunger over the working cycle, an electronic control unit (ECU) is coupled to the sensor and to the CVT and is configured to receive the signal from the sensor; and cause said CVT to modify the gear ratio based on the signal from the sensor and on a mathematical model defining a CVT gear ratio variation profile derived from an expected load applied by the crop on the plunger.

<CIT> discloses a crop baler has a plunger reciprocable through compression and retraction strokes for compressing charges of crop material into bales within the baler. The crop baler also includes a rotatable flywheel operably coupled with the plunger for transferring kinetic energy to the plunger during reciprocation of the plunger. An output shaft is operably coupled with the flywheel for rotating the flywheel and driving the plunger through its compression and retraction strokes and an input shaft is adapted to be coupled with a power takeoff shaft of a towing tractor for receiving driving power from the tractor. The crop baler also includes a continuously variable transmission operably coupled between the input and output shafts for adjusting the ratio of the angular velocities of the shafts in response to changes in the angular velocity of the flywheel while maintaining the input shaft at a substantially constant angular velocity.

<CIT> relates to an agricultural baler comprising a flywheel and a drivetrain for coupling the flywheel to a connector that is arranged to be connected to a power take-off of a tractor, wherein the drivetrain includes a decoupling mechanism for decoupling the flywheel from the connector in case of an overload.

<CIT>) relates to an agricultural baler for pressing cuboid bales, comprising a torque connection, a transmission shaft, a flywheel, a movement device, a compression element and a compression channel.

Aspects and embodiments of the disclosure provide an agricultural system and a method for controlling an agricultural baler as claimed in the appended claims.

The agricultural work vehicle (or tractor) may include one or more control devices, such as but not limited to programmable or non-programmable processors. Similarly, the baler implement may include one or more control devices, such as but not limited to programmable or non-programmable processors. Additionally, or alternatively, the baler implement may be controlled by one or more control devices of the agricultural work vehicle. Similarly, the agricultural work vehicle may be controlled by one or more control devices of the baler implement.

The agricultural work vehicle and/or the baler implement may be remote controlled, e.g. from a farm office. Accordingly, the agricultural work vehicle may include one or more communication interfaces for connection to a remote processor and/or a remote controller. Similarly, the baler implement may include one or more communication interfaces for connection to a remote processor and/or a remote controller.

There now follows a description of preferred embodiments of the invention, by way of non-limiting example, with reference being made to the accompanying drawings in which:.

Referring to the drawings a baling machine <NUM> is shown being towed behind an agricultural work vehicle (towing vehicle) that in the illustrated embodiment non-limitingly is an agricultural tractor <NUM>.

The tractor <NUM> is a conventional tractor including a vehicle frame/body 11a, rearmounted cab 11b, front, steerable, ground-engaging wheels 11c and rear, driven, ground-engaging wheels 11d. Tractor <NUM> includes at its rear end between the rear wheels 11d a power take-off <NUM> of a conventional design that includes a rotative coupling for a PTO shaft <NUM> that extends rearwardly of the tractor <NUM>. The PTO <NUM> may be engaged to cause rotation of the PTO shaft <NUM> or disengaged, such that the shaft <NUM> is not powered to rotate, for example through the operation of a control lever or pushbutton.

The tractor <NUM> may have any of a range of engine power outputs including but not limited to <NUM> hp, <NUM> hp and <NUM> hp. The baling machine <NUM> is operable when towed by any such tractor <NUM>, without a need for adjustment or modification, for the reasons explained below.

The PTO shaft <NUM> may be any of a variety of lengths. A relatively short PTO shaft <NUM> and drawbar <NUM> (described below) minimises the distance between the pick-up <NUM> (described below) of the baling machine <NUM> and the tractor <NUM>. This provides certain advantages, although in some other respects a longer PTO shaft <NUM> may provide good adjustment flexibility.

The partial driveline represented by the PTO <NUM> and PTO shaft <NUM> may in various types of tractor include a PTO clutch <NUM> that as described above seeks to protect the engine of the tractor <NUM> from damage caused e.g. when an excessive loading on the PTO shaft causes engine stalling. The PTO clutch <NUM> is shown schematically in <FIG>. It may readily be envisaged by the person of skill in the art and typically would be a one-way clutch of a kind that permits free movement when rotating in one direction, and transfers rotary drive via the PTO shaft <NUM> when rotating in the opposite direction. Other forms and locations are possible in respect of the clutch <NUM>.

The baling machine <NUM>, i.e. a baling implement, is secured to the rear of the tractor <NUM> by way of a drawbar <NUM> that typically is of an "A"-shape when viewed in plan and extends forwardly of the baling machine <NUM> below the PTO shaft <NUM>. The drawbar <NUM> is pivotably secured to a conventional towing hitch at the rear of the tractor <NUM>.

The baling machine <NUM> includes a housing or cover <NUM> that may take a variety of forms. The housing <NUM> in most baling machine designs includes a section 16a that is open to permit ejection of formed bales at the rear of the baling machine <NUM>.

Panels defining the housing <NUM> further may be openable or removable in order to permit maintenance of the interior parts of the baling machine <NUM> replacement of bobbins of twine used for tying completed bales or the clearance of blockages that can arise for a variety of reasons.

The housing <NUM> of the baling machine <NUM> is secured to a baling machine frame <NUM> selected parts 17a, 17b, 17c, 17d of which are illustrated in <FIG>, with the complete frame <NUM> being omitted for ease of illustration.

The baling machine <NUM> is mobile and to this end it includes secured to the frame <NUM> two or more ground-engaging wheels <NUM>.

In the embodiment illustrated, four wheels are provided, being left and right front wheels and left and right rear wheels <NUM>. In <FIG> the left-hand side front and rear wheels are visible.

In this regard the front or forward end of the baling machine <NUM> is the end of it that is closest to the towing tractor <NUM>, and the terms "rear", "left", "right", "upper", "lower" and derivative terms are interpreted accordingly and as though an observer is looking forwardly along the baling machine <NUM>.

The wheels <NUM> may be mounted relative to the frame <NUM> by way of suspension components and passive or active steering components as would be known to the person of skill in the art, or they may be mounted more simply. The wheels <NUM> optionally may include tyres and/or gripping elements that are omitted from <FIG> for ease of viewing.

A pick-up <NUM> projects forwardly of the baling machine <NUM> and is arranged to collect cut plant matter <NUM> lying in a field in which the baling machine <NUM> moves as influenced by the motion of the tractor <NUM>. The pick-up <NUM> passes the plant matter to a conveyor <NUM>. The conveyor <NUM> conveys the plant matter inside the baling machine <NUM> where it undergoes baling.

Numerous designs of pick-up <NUM> and conveyor <NUM> are known in the baling machine art and fall within the scope of embodiments disclosed herein. The precise designs of the pick-up <NUM> and conveyor <NUM> are essentially immaterial to the nature and operation of the invention, and therefore are not described in detail.

As mentioned, the baling machine <NUM> includes an internal bale-forming chamber <NUM>. This is an elongate, cuboidal volume defined by chamber walls of which top and bottom walls 22a and 22c are visible in <FIG>. The bale-forming chamber <NUM> in a typical baling machine design extends in a fore and aft direction in an upper part of the rear of the volume enclosed by the housing <NUM>.

The rear 22b of the bale-forming chamber coincides with the aforementioned open housing section 16a in order to allow ejection of completed bales in a per se known manner.

A crop flow path exists inside the baling machine <NUM> between the conveyor <NUM> and the bale-forming chamber <NUM>. The crop flow path may readily be envisaged and is omitted from the figures for clarity.

The forwardmost end of the bale-forming chamber <NUM> is essentially open. A plunger <NUM> occupies the interior cross-section of the bale-forming chamber <NUM> and is constrained to move longitudinally inside the chamber <NUM> from the open, forward end towards and away from the rear 22b of the bale-forming chamber <NUM> as signified by arrow A.

The PTO shaft <NUM> as mentioned may be powered to rotate, in virtually all tractors in a clockwise direction when viewed from behind the tractor <NUM>. PTO shaft <NUM> is connected by way of at least one, and in practice at least two, universal joint <NUM> to the forwardmost end of a rotary input shaft <NUM> of the baling machine <NUM>. The universal joint <NUM> in a well-known manner accommodates changes in the relative orientation of the tractor <NUM> and baling machine <NUM> that result from towing of the baling machine from place to place, e.g. while the baler is working or when it is travelling between fields.

The input shaft <NUM> is supported e.g. using journal bearings that are omitted from <FIG> for ease of viewing and connects by way of a driveline, described in more detail below, to a rotatable flywheel <NUM>.

Flywheel <NUM> is supported on a flywheel shaft <NUM> that also is supported using journal bearings, or a functionally similar arrangement, that further is omitted from <FIG>. The functions of the flywheel <NUM> are as described above, although as explained it is possible for the flywheel <NUM> in embodiments of the invention to be made considerably lighter than some prior art flywheels.

The rear end 29a of the flywheel shaft <NUM> is a rotary input to a drive converter <NUM> or similar transmission that by way of intermeshing gear components alters the axis of rotation of rotative energy in the baling machine <NUM>. This drive converter <NUM> may be referred to as a main transmission in some examples.

The nature of the drive converter <NUM> thus is such that the longitudinally extending (with reference to the elongate length of the baling machine <NUM> as illustrated) axis of rotation of the flywheel shaft <NUM> becomes rotation about a transversely extending axis of a crankshaft <NUM>.

The crankshaft <NUM> is connected to a pair of crank members (only the right one is shown as <NUM>) that protrude from the drive converter <NUM> in a manner presenting free ends. The pair of crank members and corresponding conrods (only the right one shown as <NUM>) connect the crankshaft <NUM> of the drive converter <NUM> with the forward side of the plunger <NUM>. A first, right side crank member <NUM> has a first end connected to the crankshaft <NUM> of the drive converter <NUM>. A second end of the first, right side crank member <NUM> is connected to a first end <NUM> of a first,.

right side conrod <NUM>. The first, right side conrod <NUM> has a second end <NUM> connected to the plunger <NUM>. A second, left side crank member (not shown) has a first end connected to the crankshaft <NUM> of the drive converter <NUM>. A second end of the second, left side crank member is connected to a first end of a second, left side conrod (not shown). The second, left side conrod has a second end (not shown) connected to the plunger <NUM>.

As is apparent from <FIG>, therefore, rotation of crankshaft <NUM> causes rotation of crank member <NUM>, as signified by arrow B, that gives rise to the rectilinear, reciprocal motion of plunger <NUM> indicated by arrow A.

In this regard it is somewhat arbitrary whether crank <NUM> rotates clockwise or anticlockwise, since reciprocal motion of the plunger <NUM> may in an appropriately designed set of driveline elements be achieved regardless of the direction of rotation of the crank <NUM>. The actual rotational direction of the crank <NUM> would be a consequence of the internal design of the drive converter <NUM>. Such aspects are not relevant to an understanding of the invention, and therefore are not provided in detail herein.

Charges of plant matter <NUM> conveyed inside the baling machine <NUM> from the conveyor <NUM> repeatedly are at intervals fed by internal components of the baling machine <NUM>, that are omitted from <FIG> for clarity, into the interior of the bale-forming chamber <NUM> for compaction by reason of the reciprocal, rectilinear motion (arrow A) of the plunger <NUM>. The feeding of each charge of plant matter <NUM> is timed to coincide with positioning of the plunger <NUM> at its retracted, i.e. forwardmost position, with the result that the plant matter <NUM> becomes compressed and compacted by the movement of the plunger <NUM> into bale form after it has been fed in to the bale-forming chamber <NUM>.

The driveline defined between the input shaft <NUM> and the flywheel shaft <NUM> includes a transmission <NUM> that is described below in relation to <FIG> and <FIG>.

In <FIG> the transmission <NUM> connects the rotary input shaft <NUM> to the flywheel shaft <NUM> at first and second selectable transmission ratios defined by driveline components within the transmission <NUM>.

A first transmission ratio is defined by mutually meshing, rotary, toothed gears <NUM>, <NUM> that each are supported for rotation within the transmission <NUM>. The first transmission ratio is a relatively great reduction ratio transmission providing a high degree of mechanical advantage.

A second transmission ratio is defined by mutually meshing, rotary, toothed gears <NUM>, <NUM> that each are supported for rotation within the transmission <NUM> adjacent the gears <NUM>, <NUM> in a manner defining a parallel driveline to that representing the first transmission ratio. The second transmission ratio is a relatively close reduction ratio transmission providing a higher speed of output shaft rotation than the first transmission ratio.

The baling machine <NUM> includes a control unit <NUM>, non-limitingly illustrated schematically in <FIG>, in the form of a programmable microprocessor. The baling machine <NUM> includes a source of electrical power, for the control unit <NUM>, that in preferred embodiments may take the form of a rotary generator that is driven directly or indirectly by the PTO shaft, although other sources of electrical power including batteries and other storage devices, or other types of generator, are possible. Combinations of electrical power sources furthermore are possible.

As indicated, the control unit may take a variety of forms and need not be a control unit as illustrated, or a single component.

The control unit <NUM> is capable (typically but not necessarily as a result of software and/or firmware programming) of selectively engaging the first or the second transmission ratio. The arrangement of the components and/or the programming of the control unit <NUM> prevents the first and second transmission ratios from being selected simultaneously.

As best illustrated in <FIG>, the input shaft <NUM> rigidly connects to an input gear shaft <NUM> that is supported (non-limitingly in the embodiment illustrated by way of journal bearings <NUM> at either end) for rotational movement inside the transmission <NUM>. The input gear shaft <NUM> is locked to the gear <NUM> such that the gear <NUM> always rotates with the input gear shaft <NUM>.

The input gear shaft <NUM> is also locked to an input side <NUM> of first transmission clutch <NUM> forming part of the driveline. As a result the input side <NUM> of the first transmission clutch <NUM> also rotates with the input gear shaft <NUM>.

The first transmission clutch <NUM> is e.g. electrically or electro-hydraulically activated in the described embodiment, and is selectively engageable under command from the control unit <NUM>. When engaged the output side <NUM> of the first transmission clutch <NUM> is locked to the input side <NUM> and rotates therewith.

The output side <NUM> of first transmission clutch <NUM> is locked to the gear <NUM> of the first transmission ratio such that the gear <NUM> rotates with the output side <NUM>.

In the illustrated embodiment the first transmission clutch <NUM> lies on the first gear shaft <NUM> intermediate the gears <NUM> and <NUM>, but as will occur to the person of skill in the art this need not be the case, and other clutch and gear position combinations are possible.

As explained the gears <NUM> and <NUM> are mutually meshed, with the gear <NUM> supported on the rotational intermediate gear shaft <NUM>. The intermediate gear shaft <NUM> is supported (in the non-limiting example shown by way of journal bearings <NUM> at either end) for rotation relative to the remainder of the transmission <NUM>.

By reason of locking of the input gear shaft <NUM> to the gear <NUM>, the gear <NUM> rotates whenever the input gear shaft <NUM> rotates, at a speed, relative to the speed of the input gear shaft <NUM>, determined by the gear tooth ratio between the gears <NUM> and <NUM>. However, the gear <NUM> merely idles unless a second transmission clutch <NUM>, which may be of a similar design to the first transmission clutch <NUM> and hence operable under command of the control unit <NUM>, is engaged.

In this respect, the intermediate gear shaft <NUM> is locked to an input side <NUM> of second transmission clutch <NUM>; and an output side <NUM> is locked to the gear <NUM>. As a result, when the clutch is engaged, rotation of gear <NUM> is transmitted via the intermediate gear shaft <NUM>.

The gear <NUM> is meshed with the gear <NUM> as explained. The gear <NUM> is locked to the intermediate gear shaft <NUM>. Clearly, therefore, to avoid locking up of the transmission it is essential that only one of the transmission clutches <NUM>, <NUM> is engaged at a time. When the first transmission clutch <NUM> is engaged and the second transmission clutch <NUM> is disengaged, drive from the input shaft <NUM> is transmitted via the meshed gears <NUM> and <NUM> to drive intermediate gear shaft <NUM> in accordance with the first, reduction transmission ratio "G1" determined by the numbers of teeth of gears <NUM> and <NUM>. At this time, the gears <NUM> and <NUM> rotate in an idling manner.

When the first transmission clutch <NUM> is disengaged and the second transmission clutch <NUM> is engaged, the drive of the input shaft <NUM> is transmitted via the gears <NUM> and <NUM> to the drive intermediate gear shaft <NUM> in accordance with the second transmission ratio "G2" determined by the numbers of teeth of the gears <NUM> and <NUM>.

As explained herein, the first transmission ratio G1 is a reduction ratio in which the speed ratio exceeds <NUM>. This provides a beneficial mechanical advantage when moving the flywheel <NUM> from rest. The second transmission ratio G2 is an accelerative ratio the speed ratio of which is a value less than <NUM>. This causes rotation of the flywheel shaft <NUM> to be at a higher speed than that of the PTO shaft <NUM>.

It is possible for both the clutches <NUM>, <NUM> to be disengaged simultaneously. In that case gears <NUM> and <NUM> would rotate, but no drive would be transmitted to intermediate gear shaft <NUM>.

The intermediate gear shaft <NUM> includes, mounted thereon, an optional brake <NUM> that may be employed when both the transmission clutches <NUM>, <NUM> are disengaged to slow the flywheel shaft <NUM>. The latter receives the rotary drive of intermediate gear shaft <NUM>, when one of the transmission clutches <NUM>, <NUM> is closed, via meshed output gears <NUM>, <NUM>.

The numbers of teeth of the gears <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> may be varied extensively in all the gears of the transmission <NUM> depending on the precise design of the transmission <NUM>. The overall numbers of drive-transferring components in the transmission may be varied. Also as explained the driveline elements defining the transmission ratios need not be meshing, toothed gears and instead may adopt a range of other forms, including but not limited to the examples given above.

The transmission clutches <NUM> and <NUM> may be for example electrically (e.g. solenoid) operated, electro-mechanically operated or electro-hydraulically operated, under the control of the control unit <NUM>. Preferably, but not essentially, the transmission clutches <NUM>, <NUM> are spooled wet clutches the nature of which is familiar to the person of skill in the art and therefore does not require describing in detail herein. Wet clutches generally are highly suitable for computer or other electronic control, leading to rapid clutch engagement and disengagement.

One form of control of the transmission clutches <NUM>, <NUM> is by electrical control signals transmitted from the control unit <NUM> to the first and second transmission clutches <NUM>, <NUM>. One form of control of the transmission clutches <NUM>, <NUM> is illustrated schematically by electrical control signal line <NUM> (<FIG>) that transmits commands from the control unit <NUM> to first transmission clutch <NUM>; and control line <NUM> that transmits commands from the control unit <NUM> to second transmission clutch <NUM>.

Two-way communication between the transmission clutches <NUM>, <NUM> and the control unit <NUM> optionally is possible. Using two-way control, the transmission clutches <NUM>, <NUM> can signify e.g. their operational (i.e. engaged or disengaged) status, information on the condition of wear parts such as friction plates, levels of clutch fluid in the event of the clutches being wet clutches as is preferred and similar operational variables. The control unit <NUM> can generate commands and/or warning signals in dependence on the signals received from the transmission clutches <NUM>, <NUM>.

The control unit <NUM> may further be connected to a rotational speed sensor <NUM> and/or an oil temperature sensor <NUM> via electric signal line <NUM>.

The control unit <NUM> is capable of selectively disengaging the rotary drive between the input shaft <NUM> and the shaft <NUM> supporting the flywheel <NUM>. This possibility is explained further below in connection with operational sequences made possible by the apparatus of the invention. The control unit <NUM> may also be capable of selectively activating the brake <NUM> of the transmission <NUM>. Activation of the brake <NUM> will actively slow the rotational speed of the flywheel shaft <NUM> and thus the speed of the flywheel <NUM> connected to the flywheel shaft <NUM>.

The baling machine <NUM> optionally may include one or more input devices <NUM>, represented schematically and non-limitingly in <FIG>, by means of which the operator may provide input-power-data, such as a maximum power output of the corresponding towing vehicle (tractor), to the control unit <NUM>.

In <FIG> an input device <NUM> is shown in the form of a keypad connected to the control unit <NUM> via an electrical cable <NUM>, and using which e.g. the rated power output of the tractor <NUM> can be input to the baling machine <NUM>. As will be described in more detail below, the control unit <NUM> can determine a suitable clutch-control-signal that is optimised for the input power provided by the tractor.

The input device <NUM> may take a variety of other forms and may be provided anywhere on the baler <NUM> and/or the corresponding tractor <NUM>. In some embodiments, the input device <NUM> may be provided remotely and in communication with receivers mounted on the tractor <NUM> or the baler <NUM>. The input device <NUM> may include a code reader that can read a code printed or affixed on part of the tractor <NUM>, e.g. adjacent the PTO; a near-field communications (NFC) device that establishes a communications link with a control unit forming part of the tractor <NUM> in order to download power output information; or a cable connection between the control unit <NUM> and a counterpart control unit forming part of the tractor <NUM>.

The transmission <NUM> may include a rigid housing <NUM> that may be formed e.g. by casting from a metal alloy, especially a high stiffness, lightweight alloy.

As explained the baling machine <NUM> includes a number of frame elements <NUM>. The housing <NUM> may be positioned to interconnect two or more such frame members (e.g. frame members 17a and 17b as non-limitingly illustrated in <FIG>) in a manner enhancing the stiffness of the frame <NUM> of the baling machine <NUM>.

In the illustrated embodiment such interconnection is achieved by way of perforated lugs <NUM>, <NUM> by means of which the housing <NUM> is bolted to interconnect two frame members, but as will be apparent to the person of skill in the art such interconnection may be achieved in a variety of alternative ways.

The layout of the components of the transmission <NUM> inside the housing <NUM> is such that the driveline components <NUM>, <NUM> defining the first transmission ratio occupy a first vertically extending distance in the housing <NUM>; and the driveline components <NUM>, <NUM> defining the second transmission ratio occupy a second vertically extending distance in the gearbox housing, the upper limit of the second vertically extending distance terminating below the upper limit of the first vertically extending distance.

This means that the transmission <NUM> is compact in the longitudinal dimension of the baling machine <NUM>, and also that the output of the transmission <NUM> is connected to the flywheel shaft <NUM> at a relatively high point in the baling machine <NUM>. This provides several advantages in terms of transferring drive input via the input shaft <NUM> to the location of the plunger <NUM>, which as mentioned is located relatively high inside the baling machine <NUM>.

Turning to <FIG>, there is shown a schematic flow chart of a method for controlling an agricultural baler according to an embodiment of the present disclosure. The method of <FIG> may be employed by a control unit, such as the control unit <NUM> described with reference to <FIG> above, in order to control an agricultural baler as also shown in <FIG>, for example. The method is used during start-up of the agricultural baler, that is when power is initially transferred from the PTO of the tractor to an input shaft of the baler. In some embodiments, this may be triggered by a start of the tractor engine. An agricultural baler controlled by the method shown in <FIG> includes a rotary input shaft connected by way of a baler driveline to a rotatable flywheel, the driveline including one or more clutches, such as the first and second clutches <NUM>, <NUM> described above, for controllably transferring rotary drive power between the input shaft and the flywheel.

In a first step S302, the method <NUM> shown in <FIG> comprises a step for receiving input-power-data. The input-power-data is indicative of a drive power available at the rotary input shaft, such as the input shaft <NUM> shown in <FIG>. It will be appreciated that the drive power available at the rotary input shaft is directly dependent on the drive power of the tractor PTO shaft, which, in turn, is driven by the engine of the tractor. As will be discussed in detail below, in some examples the input-power-data can include predefined-input-power-data that is received in response to input being provided by an operator of the baler. Additionally or alternatively, the input-power-data can include measured-input-power-data. The measured-input-power-data can represent measurements of one or more operating parameters of the baler and / or the tractor that are indicative of a drive power available at the rotary input shaft, and optionally whether or not that drive power is sufficient. As discussed below, the one or more operating parameters can include the rotary input shaft speed, the PTO shaft speed, and/or the tractor engine output power. For instance, if the measured-input-power-data represents a measurement of a rotational speed of the rotary input shaft or the PTO shaft, then this does not represent the absolute amount of drive power that is available at the rotary input shaft. However it does represent whether or not the drive power is sufficient, as will be discussed in more detail below. Therefore, the measured-input-power-data can still be indicative of a drive power available at the rotary input shaft - i.e. there is either sufficient drive power available or there is insufficient.

On the basis of the input-power-data provided in step S302, the method determines a clutch-control-signal in a second step S304 for controlling an amount of torque transferred from the input shaft to the flywheel via the one or more clutches. The "clutch-control-signals" may be any signal created by the control unit for controlling the way in which the clutches are engaged. In one example, the clutch-control-signal may be an electronic signal provided to a hydraulic fluid supply circuit for providing the one or more clutches with pressurised hydraulic fluid to engage the clutch to an extent that will provide the desired torque transfer.

Rather than immediately and fully engaging the one or more clutches of the agricultural baler, the method of the present disclosure can control the clutch engagement, and therefore the torque transferred by the clutch between the input shaft and the flywheel, on the basis of the input-power-data. As indicated above, the input-power-data is representative of the power available at the rotary input shaft. This will advantageously result in the flywheel being brought up to an operating speed in a more time and energy efficient way, and therefore an improved start-up of the baler. Also, the method of <FIG> can beneficially reduce the likelihood of the tractor engine stalling during start-up of the baler.

<FIG> shows four example clutch-control-signals <NUM>, <NUM>, <NUM>, <NUM> that can be determined based on received input-power-data. Each of the clutch-control-signals <NUM>, <NUM>, <NUM>, <NUM> has been scaled so that they are illustrated on a scale of <NUM>% to <NUM>% of clutch pressure / torque.

In one implementation, an operator of the baler can be presented with an interface for selecting the responsiveness of the tractor engine that they are using to provide power to the baler. For instance, the operator may be presented with three responsiveness options: (i) a highly responsive; (ii) medium responsiveness; and (iii) a low responsiveness. As will be discussed below, and as is known in the art, the engine type and many other things can affect the responsiveness of the engine. Predefined-input-power-data can then be sent to the control unit that is representative of the selected responsiveness.

If the operator selects the highly responsive option, then this selection causes predefined-input-power-data that is representative of a highly-responsive-engine to be sent to the control unit. The control unit can then determine and apply an appropriate target-control-profile as the clutch-control-signal for a highly responsive engine based on the received predefined-input-power-data. An example of such a clutch-control-signal is shown in the first plot of <FIG> with reference <NUM>. It can be seen that the clutch pressure is increased relatively quickly. This is on the assumption that the clutch will be able to transfer torque from a highly responsive engine to the flywheel relatively quickly, and that the load provided by the flywheel will not cause the tractor engine any undue difficulties.

If the operator selects the medium responsive option, then this selection causes predefined-input-power-data that is representative of a medium-responsive-engine to be sent to the control unit. The control unit can then determine and apply an appropriate target-control-profile as the clutch-control-signal for a mid-responsiveness engine based on the received predefined-input-power-data. An example of such a clutch-control-signal is shown in the second plot of <FIG> with reference <NUM>. Compared to the first plot <NUM> (for the highly-responsive engine) it can be seen that the clutch pressure in the second plot <NUM> (for the mid-responsiveness engine) is increased more slowly. This is on the assumption that the clutch will need to more slowly transfer torque from a medium responsiveness engine to the flywheel to avoid the load (provided by the flywheel) causing the tractor engine to stall.

The third plot <NUM> in <FIG> shows a corresponding clutch-control-signal for a lowresponsiveness option, where the clutch engagement is slower still.

If the operator does not provide predefined-input-power-data that is indicative of a responsiveness of the tractor engine, before the start-up procedure is initiated, then the control unit may automatically select a default target-control-profile for gradually engaging the one or more clutches. The default target-control-profile may be a highly-responsive-control-profile. In this way, the control unit may set the predefined-input-power-data as representative of a highly-responsive tractor engine.

It will be appreciated that the amount of clutch pressure that achieves <NUM>% clutch torque, as is shown in the first to third plots <NUM>, <NUM>, <NUM>, may be different for tractor engines having different power levels. For example: <NUM>% clutch torque for a high powered tractor may be 19bar, <NUM>% clutch pressure for a medium powered tractor may be <NUM> bar, and <NUM>% clutch pressure for a low powered tractor may be <NUM> bar. The clutch-control-signals of the first to the third plots <NUM>, <NUM>, <NUM> illustrate a linear change from a low clutch pressure level to a high clutch pressure level.

As discussed above, the responsiveness of the engine is an important factor that affects how quickly the clutch can be engaged. Some newer engines can take longer to deliver power than some older engines, for fuel efficiency reasons. Therefore it can be possible that a newer tier4b 470hp engine (an example of a high-power engine) requires a less steep clutch pressure curve than an older tier2 270hp engine (an example of a low-power engine), for instance. That is, the rate at which an engine can deliver its rated power will depend on the responsiveness of the engine.

In some examples separate target-control-profiles can be available for each of a plurality of engine types, and for each of the different responsiveness options that are available to the operator. Optionally a single target-control-profile may be used for a plurality of combinations of different engine types and power levels. For instance, the target-control-profile <NUM> of the first plot can be used for a more responsive tier3 270hp (low power) tractor engine. Similarly, the target-control-profile <NUM> of the second plot can be used for a less responsive tier4b 470hp (high power) tractor engine.

The fourth plot <NUM> in <FIG> shows a more sophisticated target-control-profile that can be used as the clutch-control-signal, wherein the clutch pressure level does not transition linearly from the low level to the high level. That is, the target-control-profile may have a nonlinearity. Also, the fourth plot <NUM> shows a clutch-control-signal for a clutch in a two-speed gearbox such as the gearbox that is described above with reference to <FIG>.

In the fourth plot <NUM>, at a time 't' after the clutch has been engaged, the rate of change of the clutch pressure changes from a first value (immediately before 't') to a second value (immediately after 't'). This transition is labelled as <NUM> in <FIG>, and represents a nonlinearity in the clutch-control-signal that is used to control the amount of torque transferred from the input shaft to the flywheel. In this example, the transition <NUM> occurs while the gearbox applies the same transmission ratio (that is, for the same gear in the gearbox). The specific details of the transition can be determined in a testing / configuration operation of the baler. In the present case it was found that the tractor engine could accommodate a relatively fast increase in clutch pressure initially (as represented by the steep slope in the clutch-signal before 't'), and then the rate of change of clutch pressure should be reduced after 't' to avoid the engine stalling. Such a clutch-signal <NUM> can advantageously enable the baler to be started (by getting the flywheel up to an operating speed) relatively quickly with a reduced likelihood of the tractor engine stalling.

The clutch-signal <NUM> of <FIG> also shows that the clutch can be disengaged and then re-engaged to apply a second transmission ratio, as generally indicated with reference <NUM> in <FIG>.

According to one embodiment of the present disclosure, the likelihood of engine stalling can be reduced or avoided by way of selecting an appropriate target-control-profile on the basis of the predefined-input-power-data received. In this embodiment, the predefined-input-power-data may be indicative of the responsiveness of the engine driving the rotary input shaft, which may be provided by the operator or automatically retrieved by a control unit. On the basis of the predefined-input-power-data the control unit may be able to accurately select an appropriate target-control-profile that will match the available power output of the engine and thus avoid inadvertent stalling.

In some embodiments, an operator of the baler can also, or instead, be presented with an interface for selecting the power level of the tractor engine that they are using. For instance, the operator may be presented with three power level options: (i) a high-power tractor; (ii) a mid-power tractor; and (iii) a low-power tractor.

If the operator selects the high-power-tractor, then this selection causes predefined-input-power-data that is representative of a high-power tractor to be sent to the control unit. The control unit can then determine and apply an appropriate target-control-profile as the clutch-control-signal for a high-powered tractor based on the received predefined-input-power-data. The control unit can perform similar processing for a mid- and low-power tractor. In determining and applying the appropriate target-control-profile, the control unit may set a maximum-pressure-value based on the power level of the tractor. The maximum-pressure-value can determine the end point of the pressure plots that are shown in the first to third plots in <FIG> in particular. In this way, a high-power target-control-profile, having a maximum-pressure-value of <NUM> bar for example, may be predetermined to be suitable for engine with an output power of <NUM> HP or more. A low-power target-control-profile, having a maximum-pressure-value of <NUM> bar for example, may be predetermined to be suitable for engines with an output power between <NUM> HP and 319HP. A mid-power target-control-profile, having a maximum-pressure-value of <NUM> bar for example, may be predetermined to be suitable for engines with an output power between <NUM> HP and <NUM> HP. Each of these power-related target-control-profiles will set the maximum-pressure-value of fluid pressure that will be applied to the clutch, such that it is suitable for the corresponding power rating of the tractor engine. Of course, there may be any number of target-control-profiles for different ranges of engine output powers and types.

Each of the target-control-profiles that are described with reference to <FIG> can be considered as one of a plurality of predetermined target-control-profiles.

<FIG> shows a schematic flow chart of another method for controlling an agricultural baler according to an embodiment of the present disclosure.

In a first step S502, the method involves receiving input-power-data, which in this example is measured-input-power-data. The measured-input-power-data represents measurements of one or more operating parameters of the baler and / or the tractor (or more generally, of the agricultural system, which may or may not include the tractor). For instance, the measured-input-power-data may represent one or more of: the rotary input shaft speed, the PTO shaft speed, and/or the tractor engine output power. Each of these measures can indicate an ability of the tractor engine to meet the load requirements of the flywheel, especially during start-up when accelerating the flywheel up to its operating speed can require a lot of energy from the tractor engine.

At step S504, the method involves determining an error-factor. The error-factor can represent an indicator that one or more of the measurements has dropped below an expected value. For instance, the error-factor can include a binary flag that is set if a measurement drops below a threshold value, because this can be an indicator that the tractor engine is at risk of stalling. Also, the error-factor can include an error-value that represents the difference between the measurement and a threshold value. Furthermore, the error-factor can include a binary flag that is set if a rate-of-change (optionally a negative rate-of-change) of the measurement exceeds a threshold value. Further still, the error-factor can include a derivative-value that represents the difference between the rate of change (derivative with respect to time) of the measurement and a threshold value. Each of these examples of an error-factor can be indicative of the tractor engine not having sufficient power to continue to power the flywheel at the current level of clutch engagement.

At step S506, the method includes determining the clutch-control-signal based on the error-factor. As will be discussed below, this can involve determining a correction-factor for applying an offset to a current level of the clutch-control-signal to decrease the rate at which torque is transferred to the flywheel via the one or more clutches. This can either maintain a current clutch pressure (instead of increasing it) or can reduce the clutch pressure. This example enables the control unit to dynamically control the clutch such that the baler is started up (and the flywheel is brought up to speed) in a quick and efficient manner, with a reduced risk of the tractor engine stalling. Advantageously, the control unit may not require operator input because it can start off with a clutch-control-signal that assumes that a highly-responsive tractor engine is available, and only reduce the speed with which the clutch is engaged (by reducing the slope of the clutch-control-signal) if the measured operating parameters indicate that the tractor engine is at risk of stalling.

With reference to <FIG>, there are shown the values of various baler parameters during an exemplary baler start-up process according to an embodiment of the present disclosure. The diagram of <FIG> shows the following parameters:.

Turning to the input shaft speed <NUM>, the engine of the tractor is started at a time t<NUM>, which relates to around <NUM> seconds in <FIG>. In the combination of the tractor and agricultural baler used for the measurements shown in <FIG>, the tractor engine provides PTO shaft speeds, and therefore, baler input shaft speeds <NUM> of around 500rpm when the engine is first started, and no load is connected to the input shaft. It will be appreciated that this input shaft speed is dependent on the engine used and shall not be limiting to the scope of the present disclosure.

Before the start-up procedure of the baler is initiated via the method of the present disclosure, the control unit will prompt the operator to increase the input shaft speed <NUM> (and hence the PTO shaft speed) to a level that is suitable for efficient operation of the baler. In this example, the target input shaft speed is 862rpm. Alternatively, the control unit may automatically increase the output speed of the tractor engine so as to increase the input shaft speed <NUM> without the operator being required to increase the speed manually. This automatic control of the tractor engine output speed may be in response to an operator providing input for initiating the baler start-up procedure.

Once the input shaft speed <NUM> has reached the desired value, the start-up process can be initiated. In some examples, the control unit may monitor the input shaft speed <NUM> once it is up to speed, and before the clutch is engaged, to determine the value of the desired input shaft speed <NUM> that will be used during the clutch engagement operation. For example, if the input shaft speed has been successfully brought up to 862rpm, then this value will be used for the desired input shaft speed <NUM>. If, however, it was only possible to bring the input shaft speed up to 850rpm, then this value will be used as the desired input shaft speed <NUM>. This can enable any unexpected variance in the "normal" input shaft speed to be accommodated by the algorithm. Alternatively, a predetermined fixed value can be used as the desired input shaft speed <NUM>.

The input shaft speed <NUM> is an example of measured-input-power-data, and it is data that is indicative of whether or not sufficient drive power is available at the rotary input shaft. The control unit can process the input shaft speed <NUM> to determine the clutch-control signal (for setting the clutch-pressure <NUM>). Furthermore, the control unit can determine one or both of (i) the error-value <NUM>; and (ii) the derivative-value <NUM>, based on the input shaft speed <NUM>. The control unit can then determine the clutch-control signal based on one or both of (i) the error-value <NUM>; and (ii) the derivative-value <NUM>. Further details are provided below.

In the embodiment of <FIG>, the method is initiated at a time t<NUM>. The starting time t<NUM> may be automatically chosen by the control unit at a predetermined time after the input shaft speed <NUM> was brought up to its full operating speed (about 862rpm in this example), or once the input shaft speed <NUM> has remained above a set speed-threshold (such as 850rpm) for a predetermined period of time.

At time t<NUM>, the control unit applies a clutch-control-signal such that the clutch pressure <NUM> starts to increase with an initial slope / gradient. This initial-gradient may be a predetermined gradient, and may be a maximum-gradient in an attempt to start up the baler as quickly as possible. In one example, the maximum-gradient can correspond to a 7bar/s increase in the clutch-pressure <NUM>.

As shown in <FIG>, increasing the clutch-pressure <NUM> at the initial-gradient is achievable until a time t<NUM>, at which time the input shaft speed <NUM> has started to drop. This indicates that the tractor engine is unable to provide sufficient torque to continue to accelerate the flywheel at the current rate of clutch engagement. As can be seen from <FIG>, this is the instant in time that the flywheel speed <NUM> starts to increase and therefore the load on the tractor engine has suddenly increased significantly.

While the clutch is being engaged, the control unit is subtracting the input shaft speed <NUM> from the desired input shaft speed <NUM> in order to calculate the error-value <NUM>. Also, the control unit is calculating the rate of change of the input shaft speed <NUM> in order to determine the derivative-value.

In this example the control unit compares the error-value <NUM> with an error-value-threshold <NUM>, and if the error-value <NUM> exceeds the error-value-threshold <NUM>, then the control-unit determines a clutch-control-signal that has a reduced rate of change. This can be seen from <FIG> after t<NUM>, where the clutch-pressure <NUM> initially flattens out from its initial-gradient and then has a negative gradient.

In this example, the control unit also compares the derivative-value <NUM> with a derivative-value-threshold <NUM>, and if the derivative-value <NUM> falls below the derivative-value-threshold <NUM>, then the control-unit determines a clutch-control-signal that has a reduced rate of change. The deceleration of the PTO shaft, as represented by the derivative-value <NUM>, is directly proportional to the shortfall in the amount of power that is available for driving the flywheel.

In this way, the control unit can alter the clutch-control-signal (and hence the clutch-pressure <NUM>) so as to reduce the amount of torque transferred from the input shaft to the flywheel.

<FIG> illustrates a sophisticated control algorithm in that it can take into account both the error-value <NUM> and the derivative-value <NUM> when determining the clutch-control-signal. Using the derivative-value <NUM> can advantageously enable any sharp changes in the input shaft speed <NUM> to be identified quickly such that remedial action can be taken by adjusting the slope of the clutch-control-signal. Using the error-value <NUM> can advantageously enable any slower changes in the input shaft speed <NUM> to be identified such that remedial action can be taken by adjusting the slope of the clutch-control-signal. Therefore, particularly good control can be achieved by determining the clutch-control-signal on the basis of both the error-value <NUM> and the derivative-value <NUM>. Nonetheless, in other embodiments, the control unit can determine the clutch-control-signal on the basis of only one of the error-value <NUM> and the derivative-value <NUM>, or on the basis of the input shaft speed <NUM> directly (such as by comparing the input shaft speed <NUM> with a threshold).

At time t<NUM>, the error-value <NUM> has dropped below the error-value-threshold <NUM> and the derivative-value <NUM> has dropped below the derivative-threshold-value <NUM>. At this point (e.g. at the time t<NUM>), the control unit may determine the clutch-control-signal such that the clutch pressure <NUM> starts to increase with a predetermined slope / gradient. This gradient may be the initial-gradient, or a reduced-gradient (i.e. one that is less than the initial-gradient. It can be advantageous to apply a reduced-gradient on the assumption that the initial-gradient is unsustainable for the size of the tractor engine that is being used to power the baler. The reduced-gradient may be predetermined, or may be set by the control unit based on one or more of the input shaft speed <NUM>, the error-value <NUM> and the derivative-value <NUM> (or any other measured-input-power-data, or derivative thereof). The clutch-pressure <NUM> profile shown in <FIG>, thus, starts to increase again at the time t<NUM> since the input shaft speed <NUM> is back up to (or near enough to) its desired input shaft speed of 862rpm. Also, the flywheel speed <NUM> has moved away from zero.

In this way the reduction of the clutch pressure, and the reduction in torque transfer from the input shaft, can be temporary, e.g. for as long as the error-value <NUM> remains above the error-value-threshold <NUM> and / or the derivative-value <NUM> remains below the derivative-value-threshold <NUM>. To this end, the control unit may decrease the clutch-pressure <NUM> temporarily, shortly after the error-value has exceeded the error-value-threshold <NUM> and or the derivative-value <NUM> falls below the derivative-value-threshold <NUM>. The decrease in clutch-pressure <NUM> can be temporary in order to enable the input shaft speed <NUM> (and hence also the tractor engine) to recover with a reduced load due to increased slip in the clutch. Once the input shaft speed <NUM> has recovered, the clutch-pressure can potentially start to be increased at a faster rate again without stalling the tractor engine.

At a time t<NUM>, the clutch-pressure <NUM> yet again reaches <NUM> bar, meaning an amount of torque transferred by the clutch is identical to the torque transferred at the time t<NUM>. However, at the time t<NUM>, i.e. about <NUM> second later than when the clutch-pressure <NUM> reached <NUM> bar for the first time at time t<NUM>, the speed of the flywheel <NUM> has increased and a rate of change of the clutch-pressure <NUM> is lower than it was previously. This is an example of a relatively slowly responsive engine because it needed one second to ramp up the injection in order to deliver the required torque at that speed of the PTO. In the example of <FIG>, the start-up with the initial-gradient in the clutch-pressure <NUM> was too fast for the engine T3, such that at time t<NUM> the control unit automatically delayed full engagement of the one or more clutches by decreasing the clutch-pressure temporarily until time t<NUM>.

As discussed above, the amount of reduction in clutch-pressure <NUM>, and therefore the amount of decrease in torque transferred to the flywheel, may be based on the error-value. In one example, the control unit may reduce the clutch-pressure <NUM> by an amount that depends on the size of the error-value <NUM>. In other words, a correction-factor (which represents a decrease in the amount of torque transferred to the flywheel) may be related to (optionally directly proportional to) the error-value <NUM>. Similarly, the control unit may set the correction-factor for the clutch-pressure <NUM> based on the size of the derivative-value <NUM>. Alternatively, the control unit may apply a correction-factor that has a predetermined, fixed, value to reduce the clutch-pressure <NUM> in response to the error-value <NUM> exceeding the error-value-threshold and / or the derivative-value <NUM> dropping below the derivative-value-threshold.

At time t<NUM> the error-value <NUM> exceeds the error-value-threshold <NUM> X for a second time, and the derivative-value <NUM> also drops below the derivative-value-threshold <NUM>. The control unit again reacts by decreasing the slope of the clutch-pressure <NUM> in order to delay full engagement of the one or more clutches and thereby provide more time for the tractor engine to reach its optimal working condition. Similar to the above, the slope of the clutch-pressure <NUM> may be reduced until a time t<NUM>, at which point the error-value <NUM> has dropped below the error-value-threshold <NUM>. After t7, the control unit may determine the clutch-control-signal such that the clutch pressure <NUM> starts to increase with a predetermined slope / gradient. This gradient may be the same as an earlier used gradient, or may be a further-reduced-gradient (i.e. one that is less than the reduced-gradient).

The one or more clutches are fully engaged in this example when the clutch-pressure <NUM> has reached <NUM> bar. Also, the tractor engine is able to maintain the input shaft speed at a sufficiently high value (such that the error-value <NUM> does not exceed the error-value-threshold <NUM>). At this point, the clutch-pressure <NUM> reaches a plateau <NUM> during which the clutch-pressure is maintained at <NUM> bar, i.e. the one or more clutches are fully engaged, for a predetermined period of time, such as the time required for the plunger to reach its fully retracted position.

The clutch-control-signal that controls the clutch-pressure <NUM> as shown in <FIG> may be applied by the control unit during start-up of the agricultural baler, e.g. when the transmission is set to its first selectable transmission ratio G1 by means of the first clutch <NUM>. Once the first clutch <NUM> is fully engaged, a gear-change may be initiated at time t<NUM>, at which point the clutch-pressure <NUM> of the first clutch <NUM> is significantly reduced to disengage the first clutch <NUM> and select the second transmission ratio G2 by gradually pressurising the second clutch <NUM>.

The embodiment described above includes the use of a dynamically defined clutch-control-signal based on measured-input-power-data (the input shaft speed <NUM>). In the example of <FIG>, the available power output of the engine was too low for the initial-gradient, such that the gradient of the clutch-pressure profile <NUM> was reduced to avoid stalling. In one embodiment, the control unit may be configured to store a transcript of the clutch-control-signal (that results in the clutch-pressure <NUM> shown in <FIG>) as prior-clutch-control-data for future use. The prior-clutch-control-data may be used directly as a new target-control-profile for future baler start-up procedures (such as the ones shown in <FIG>).

In another embodiment, before t<NUM>, when the start-up procedure is initiated, the control unit may prompt the user to enter predefined-input-power-data indicative of the responsiveness of the tractor engine that is driving the rotary input shaft. Alternatively, the control unit may be configured to automatically determine the predefined-input-power-data (e.g. the engine performance) before the start-up procedure is initiated. As will be described in more detail below, this predefined-input-power-data that is indicative of the responsiveness of the tractor engine may be used by the control unit to determine a suitable target-control-profile for controlling the engagement of the one or more clutches. This is in contrast to the embodiment of <FIG>, in which the clutch-pressure is initially increased at a gradient that is chosen irrespective of the particular output performance of the corresponding tractor engine.

Generally, it will be understood that the control unit may choose a faster start-up procedure, i.e. determine clutch-control-signals that fully engage the one or more clutches within shorter periods of time (e.g. profiles <NUM>, <NUM> of <FIG>), if the predefined-input-power-data indicates that the tractor engine has a highly responsive power output. Similarly, the control unit may choose a slower start-up procedure if the predefined-input-power-data indicates that the tractor has a less responsive engine (e.g. profile <NUM> of <FIG>).

The control unit may have access to a plurality of predetermined target-control-profiles. Examples of target-clutch-control-profiles are illustrated in the plots <NUM>, <NUM>, <NUM>, <NUM> depicted in <FIG>. Each of the plurality of predetermined target-control-profiles (e.g. <NUM>, <NUM>, <NUM>, <NUM>) available to the control unit may be suitable for a range of tractor engine responsiveness levels. Generally, the target-control-profiles for a highly responsive tractor engine (e.g. plots <NUM> and <NUM>) will be applicable to increase the amount of torque transferred from the input shaft to the flywheel quicker than target-control-profiles for a less responsive tractor engine (e.g. plots <NUM>, <NUM>).

As explained above, if the one or more clutches are engaged too quickly (e.g. the amount of torque transferred from the input shaft to the flywheel is ramped up too quickly for a tractor engine that does not have the available torque), then engine stalling may be the result. In the example above, this could be the case if the highly-responsive target-control-profile <NUM> was applied to a tractor engine with a low responsiveness. This may, for example, occur if a target-control-profile that is suitable for a highly responsive tractor engine is used for a less responsive tractor engine.

In one embodiment, the control-unit may be configured to receive both predefined-input-power-data and measured-input-power-data. In this embodiment, even if the target-control-profile, which was chosen on the basis of the predefined-input-power-data, is too steep (i.e. the clutch pressure is increased too quickly for the responsiveness of the engine), the control unit is still able to adjust the clutch-control-signal on the basis of the measured-power-input-data to avoid stalling. In other words, in this embodiment, the control-unit will employ the target-control-profile as the clutch-control-signal for as long as no significant decrease in the speed of the input shaft is detected. Should an unacceptable decrease in the speed of the input shaft be detected on the basis of the measured-input-power-data, the control unit will change (e.g. temporarily decrease) the gradient of the clutch-pressure to deviate from the chosen target-control-profile to avoid stalling. Then, when the input shaft speed has returned to an acceptable value, the control-unit will employ the target-control-profile as the clutch-control-signal again.

In yet another embodiment, prior-clutch-control-data (explained above) may be used to determine the predefined-input-power-data provided to the control-unit. This may be an alternative to an operator manually providing the engine responsiveness during the baler start-up. The control-unit may be configured to check if prior-clutch-control-data is available before the baler start-up is initiated. If prior-clutch-control-data is available, the control unit may be configured to use the prior-clutch-control-data automatically for determination of the clutch-control-signal. Alternatively, the control unit may be configured to prompt the operator to determine whether the prior-clutch-control-data should be used by the control unit. The operator may then provide a trigger-input to confirm that the control unit should make use of the prior-clutch-control-data. In one example, the trigger-input may be provided via a touch screen interface. The operator may choose not to use the prior-clutch-control-data, for example, if a new tractor is connected to the baler for the first time and the prior-clutch-control-data was recorded with a different tractor.

On the basis of the prior-clutch-control-data, the control unit may be able to accurately determine the responsiveness of the engine (i.e. determine predefined-power-input-data) and select a suitable target-control-profile from a plurality of predetermined target-control-profiles available (e.g. one of the clutch-control-signals <NUM>, <NUM>, <NUM>, <NUM> shown in <FIG>). In one example, after a first baler start-up, the dynamically determined clutch-pressure profile <NUM> of <FIG> may be provided to the control unit as prior-clutch-control-data and may be used by the control unit to determine the responsiveness of the tractor engine. After determination of the responsiveness of the engine on the basis of the prior-clutch-control-data, the control unit may start the baler on the basis of a suitable target-control-profile in the future.

Claim 1:
An agricultural system comprising:
an agricultural baler (<NUM>), comprising a rotary input shaft (<NUM>) connected by way of a baler driveline to a rotatable flywheel (<NUM>), the driveline including one or more clutches (<NUM>, <NUM>) for controllably transferring rotary drive between the input shaft (<NUM>) and the flywheel (<NUM>); and
a control unit that is configured to, as part of a start-up procedure of the agricultural baler (<NUM>) when power is initially transferred from an agricultural work vehicle to the input shaft (<NUM>):
receive input-power-data indicative of a drive power available at the rotary input shaft (<NUM>); and
determine a clutch-control-signal for controlling an amount of torque transferred from the input shaft to the flywheel via the one or more clutches, on the basis of the input-power-data,
wherein the one or more clutches (<NUM>, <NUM>) are friction clutches and the clutch-control-signal is applicable to set a clutch-pressure applied to engage friction surfaces of the one or more clutches (<NUM>, <NUM>), and wherein:
the input-power-data comprises measured-input-power-data that represents measurements of one or more operating parameters of the agricultural system or the agricultural work vehicle, and characterised in that
the control unit is configured to:
determine an error-factor that is an indicator that one or more of the measurements has dropped below an expected value, and
determine the clutch-control-signal for decreasing a rate at which torque is transferred to the flywheel via the one or more clutches based on the error-factor.