Baler and method for making round bales

Abstract

A baler (1) for forming round bales of agricultural products, includes: a frame (T) providing an internal volume; a compression chamber (C); a plurality of guide rollers (3) placed inside the internal volume; a plurality of belts (4); a tensioning system which includes a first tensioning arm (601) and a second tensioning arm (602) articulated to the frame, a hydraulic actuator (603), associated with the first or the second arm, and an elastic unit, associated with the first or the second arm. The baler includes a tailgate which is movable between an open position and a closed position for allowing a formed bale to be ejected from the compression chamber, wherein the tailgate is at the open position with the tensioning arms at the full bale position. The hydraulic cylinder is pressurized at a first predetermined pressure value during the closing of the tailgate, and at a second pressure value, lower than the first pressure value, during the opening of the tailgate, so as to obtain a slippage of the belts during the opening of the tailgate.

Description

[0001] DESCRIPTION

[0002] BALER AND METHOD FOR MAKING ROUND BALES

[0003] Technical field

[0004] This invention relates to a baler and to a method for making round bales.

[0005] Background art

[0006] Round balers are the most widely used agricultural machines that can be attached to the rear of a machine such as a tractor, for gathering previously cut agricultural products such as rice straw, grass, wheat straw, maize straw and the like, from the ground (hereinafter referred to as "hay"), forming a bale from that hay and unloading the bale onto the field. Typically, balers have a feed unit capable of picking up the hay from the ground, a compression chamber for forming the round bale, and a rotor apparatus for feeding the hay collected from the ground to the compression chamber of the balers. The compression chamber may have a fixed volume or a variable (progressively increasing) volume. In the case of a variable-volume baler, the compression chamber is delimited by a plurality of endless belts wound around the compression chamber and moving continuously around it. The plurality of belts are driven by a plurality of guide rollers. In particular, a portion of each belt is stretched between two consecutive guide rollers, and the belt tensioned between the two rollers must deform under the incoming hay in order to conform to the shape of the round bale being formed inside the compression chamber.

[0007] The balers are also equipped with a tensioning system to keep belt tension constant and to release the amount of belt required to increase the size of the bale being formed. Normally, there are two rigid tensioning arms, parallel to each other, articulated at a point, and provided with a series of rollers at the opposite end where the belts are wound. In addition, actuators and tensioning means are used to control the upward and downward movement of the arms in order to control belt tension while the bale is being formed and then unloaded. In particular, movable guide rollers are mounted on the tensioning arms of the tensioning system. Consequently, the movable rollers move as a result of the upward and downward movement in order to deform the belt path. Thus, when the hay enters the baler and comes into contact with a portion of the belts, the belts are bent by the force exerted on them by the bale being formed and the tensioning arm begins to move upward. Following the movement of the tensioning arm upward, the movable guide rollers move to deform the belt path and release the length of belt needed to form the bale inside the compression chamber. Moreover, a thrust force is applied to the tensioning arms to maintain belt tension and prevent the belts from slackening during the expansion and contraction of the chamber. An elastic unit is also provided to move the arms downward after the bale has been released.

[0008] The balers also include a tailgate which is movable between an open position, for unloading the formed bale, and a closed position, during bale formation inside the compression chamber.

[0009] In this context, patent documents US9295198B2, US4545298A, EP2661953B1 and EP1595439B1 describe well-known balers equipped with tensioning systems to control bale density, with hydraulically or electrically driven actuators that allow the tensioning arms to move up and down.

[0010] At the moment the bale is unloaded, the tailgate must be opened using suitable actuators.

[0011] For this purpose belt tension must be reduced, since opening the tailgate requires a loosening movement of the belts, otherwise the tailgate actuator must overcome an additional force to raise and open the tailgate. In prior art machines, this occurs in such a way that the belt tension is set to zero, which means depressurizing the tensioning system.

[0012] In this context, document US9295198B2 describes the use of a bypass valve to set the tension to zero when the tailgate is fully open or when it starts being moved to the open position.

[0013] Document EP1595439B, on the other hand, describes a solution where the tension of the belts, when the tailgate is opened, is reduced to a value which allows further operation without belt slippage. Other examples of prior art balers are disclosed in patent documents EP2661953A, W02024003738A, AU2009339432A and EP3199016B.

[0014] However, the balers of the prior art have some disadvantages and can be improved.

[0015] Aim of the invention

[0016] This invention has for an aim to provide a baler which overcomes the above- mentioned disadvantages of the prior art.

[0017] According to an aspect of it, this disclosure provides a baler. The baler is configured for forming round bales. The round bales are formed of agricultural products. The baler comprises a frame. The frame provides an internal volume.

[0018] The baler comprises a compression chamber. The compression chamber is configured to compress the agricultural products to form the bale.

[0019] The baler includes a plurality of guide rollers. The guide rollers are placed inside the internal volume. The baler includes a plurality of belts. The belts are placed side by side in the internal volume. The belts are wound around the guide rollers. In particular, the belts are wound around the guide rollers so as to define an endless loop. The loop is deformable to delimit the compression chamber.

[0020] The baler includes a tensioning system. The tensioning system is configured to apply a tension to the belts. The tensioning system is configured to apply a tension to the belts so as to generate a corresponding pressure on the agricultural products contained inside the compression chamber. The tensioning system includes a first tensioning arm. The first tensioning arm is articulated to the frame. The first tensioning arm is articulated to the frame, to move between a bale starting position, where the formation of the bale starts, and a full bale position, where a complete bale is formed inside the compression chamber. The tensioning system includes a second tensioning arm. The second tensioning arm is articulated to the frame.

[0021] The second tensioning arm is articulated to the frame to move between the bale starting position and the full bale position.

[0022] The tensioning system includes an actuator. The actuator comprises a hydraulic cylinder. The hydraulic cylinder is associated with the first or the second arm. The hydraulic cylinder is configured to apply a force to the first and the second arm. The hydraulic cylinder is configured to apply a force to the first and the second arm in order to adjust the tension of the belts.

[0023] The tensioning system includes an elastic unit. The elastic unit is associated with the first or the second arm. The elastic unit is configured to force the arms towards the bale starting position.

[0024] The baler includes a hydraulic circuit. The hydraulic circuit is configured to feed actuating oil to the hydraulic cylinder.

[0025] The baler includes a tailgate. The tailgate is movable between an open position and a closed position. At the closed position, the tailgate is configured to allow a formed bale to be ejected from the compression chamber. The tailgate is at the open position when the tensioning arms are at the full bale position.

[0026] The baler includes a control unit for adjusting the pressure in the hydraulic cylinder. The control unit adjusts the pressure in the hydraulic cylinder so as to control the tension of the belts.

[0027] The control unit is configured to pressurize the hydraulic cylinder at a first predetermined pressure value in an opening configuration, between the open position and the closed position.

[0028] The control unit is configured to pressurize the hydraulic cylinder at a second predetermined pressure value at a closing configuration, between the closed position and the open position. The first pressure value is smaller than the second pressure value. The first pressure is set so that there is a slippage in the belts in the open configuration.

[0029] It should be noted that the term "pressurized" is used to denote a condition where the pressure inside the hydraulic cylinder is greater than the ambient pressure.

[0030] Thus, pressurization during opening of the tailgate is sufficient to allow belt slippage but prevents complete depressurization, thus keeping the tailgate actuator in operational conditions without additional loads.

[0031] Unlike prior art solutions, where the hydraulic cylinder is completely depressurized when the tailgate is opened, the solution of this invention, in one embodiment of it, keeps the pressure at a minimum level to allow controlled slippage. In an example, the control unit is configured to receive signals in real time from one or more sensors which detect the effective slippage of the belts during opening of the tailgate. These signals can be used to adjust the pressure of the hydraulic cylinder automatically so as to keep slippage with a predefined optimal limit, so that slippage is never excessive or insufficient. The slippage sensors may be optical, magnetic or rotational speed sensors, mounted in proximity to the guide rollers and configured to compare the relative speed between belt and roller.

[0032] In an example, the first pressure value is controlled dynamically on the basis of the feedback from the sensors and indicating belt slippage.

[0033] In an example, the control unit is configured to store and regulate the pressure values over time based on historical operating conditions.

[0034] Therefore, according to an aspect of this disclosure, the hydraulic cylinder is pressurized both during opening of the tailgate to facilitate its opening, and during the closing of the tailgate to help the elastic unit tension the belts. Pressurizing the belts when the tailgate is closing is important because if the tailgate closes too quickly, the belts risk not being tensioned in time, causing them to remain trapped in the tailgate. On the other hand, pressurizing the belts when the tailgate is opening allows the tailgate to be opened more easily without opposing the tailgate opening actuator.

[0035] In particular, belt tension when the tailgate is opening is reduced to a value above zero so as to obtain belt slippage. In addition, this solution allows controlling and regulating the pressure value during tailgate opening so as to obtain a desired slippage.

[0036] In particular, the applicant has found that a certain amount of belt slippage in a baler is useful when the tailgate is opening, whereas excessive slippage may have disadvantages such as, for example, causing the belts to overlap. Obtaining belt slippage allows temporarily stopping the belts while the tailgate is opening to unload the formed bale, thus making it possible to unload the bale more efficiently and reliably. In the case where the baler has a bale binding system, this aspect is useful when the bale stops to reverse the motion / rotation for unloading purposes. It should be noted that the bale rotates in a first direction during compression (when the bale is being formed) and the initial step of opening the tailgate, whereas the bale rotates in a second direction, opposite of the first direction, to eject and unload it from the baler (the final step of opening the tailgate) so as to allow reducing the pressure of the belts, which are tensioned and in rotation, and which, while the tailgate is opening, push the bale against the frame and / or against the ramp in order to eject the bale.

[0037] This pressing / pushing action can damage / tear the bale and, for example, the net used to bind the bale before it is unloaded, mainly in the central part of it (usually that where density / pressure is highest).

[0038] Thus, briefly slackening the belts while the tailgate is opening allows the temporarily stopping and slippage thereof, thereby reducing the risk of damaging the bale (and, where present, the net wound around the bale); it also allows the bale to be unloaded from the baler more quickly and easily. On the other hand, excessive slippage and / or slackening of the belts during opening of the tailgate, or slippage for an excessive length of time, may cause the belts to undergo an undesirable transversal / following movement, with the risk of the belts overlapping and / or being turned upside down.

[0039] Therefore, pressurizing the belts at a reduced value during opening of the tailgate makes opening easier and allows controlling belt slippage so that the bale can be unloaded more quickly and easily, without the risk of damaging it, for example without damaging the net. In an example, the predetermined pressure values are variable.

[0040] Such a solution allows obtaining different amounts of belt slippage to variable extents, thus better controlling the slippage.

[0041] In an example, the control unit is configured to modify the predetermined pressure values in response to input values entered by the user.

[0042] Alternatively, the control unit may be configured to modify the predetermined pressure values in response to a plurality of control parameters.

[0043] Thus, it is possible to adjust the pressurization of the cylinder, which determines the density of the bale during its formation, and also the slippage of the belts during opening of the tailgate, automatically and in a particularly precise manner.

[0044] For example, these control parameters may be representative of belt slippage.

[0045] In an example, the control unit is configured to store a history of the pressure values and of the related belt behaviour so as to allow the predetermined pressure values to be dynamically adapted as a function of belt wear or operating conditions.

[0046] In an example, the control unit is configured to adjust the pressure in the hydraulic cylinder based on a plurality of predetermined setpoint values. The setpoint values for each layer of the bale are determined while the bale is being formed.

[0047] This solution allows the density of the bale to be precisely adjusted to obtain the desired density for each layer of the bale.

[0048] In an example, the setpoint value of the pressure in the closing configuration is smaller than the maximum value of the predetermined setpoint values.

[0049] In an example, the value of the pressure in the hydraulic cylinder in the bale starting position may be equal to that of the opening configuration.

[0050] In an example, the plurality of predetermined setpoint values is set so that the maximum amount of pressure in the hydraulic cylinder is obtained in a step of binding the bale. In the step of binding, the formed bale is wrapped in a film or net.

[0051] In an example, the second pressure value (in the step of closing the tailgate) is higher than a pressure adopted in an initial step of bale formation and lower than a pressure adopted in a final step of bale formation.

[0052] Pressurizing the cylinder during opening of the tailgate at a value which falls within this range allows the tailgate to be opened easily and safely without interference from the belts, thereby obtaining slippage which is not excessive so that the bale can be unloaded more quickly and easily without the risk of overlapping the belts and of damaging the bale.

[0053] In an example, the control unit is configured to adjust belt tension through a flow regulating device; the flow regulating device may include a proportional valve, an electronically controlled valve, a variable throttle valve or a combination of these.

[0054] In an example, the control unit is configured to adjust the tension of the belts through a proportional valve.

[0055] This solution allows belt tension to be adjusted in a particularly efficient and precise manner.

[0056] The elastic unit may be a mechanical spring (for example, a spiral spring or a leaf spring), a hydraulic accumulator (diaphragm, piston or bag accumulator), a pneumatic cylinder or an electromechanical actuator configured to simulate elastic behaviour. The elastic unit may also comprise a combination of these elements.

[0057] In an example, the elastic unit may comprise a fluid accumulator. The fluid accumulator may comprise a gas volume. The accumulator functions in response to the movement of the arms in order to take the tensioning arms back to the bale starting position after the bale has been unloaded, so that in the absence of any external force, the tensioning arms are kept in the bale starting position. The elastic unit has a hydraulic circuit to feed oil to a fluid side of the accumulator.

[0058] In an example, the elastic unit has a closed hydraulic circuit which is separate from the hydraulic circuit. The fluid accumulator is connected to the cylinder through a closed hydraulic circuit independent of the hydraulic circuit which controls the actuator.

[0059] Alternatively, the elastic unit may comprise one or more springs.

[0060] According to another aspect of it, this disclosure provides a method for forming round bales.

[0061] The method comprises a step of providing a baler with a plurality of guide rollers. The guide rollers are placed inside an internal volume in the baler.

[0062] The method comprises a step of placing a plurality of belts side by side in the internal volume. The method comprises a step of winding the belts around the guide rollers so as to define an endless loop. The loop is deformable to delimit a compression chamber.

[0063] The method comprises a step of applying a tension to the belts so as to generate a corresponding pressure on the agricultural products contained inside the compression chamber.

[0064] The method comprises a step of moving a pair of tensioning arms between a bale starting position, where the formation of the bale starts, and a full bale position, where a complete bale is formed inside the compression chamber.

[0065] The method comprises a step of applying a force to the first and the second arm to adjust the tension of the belts through a respective actuator. The actuator comprises a hydraulic cylinder.

[0066] The method comprises a step of forcing the arms towards the bale starting position through an elastic unit. The elastic unit is associated with the first or the second arm.

[0067] The method comprises a step of feeding actuating oil to the hydraulic cylinder through a hydraulic circuit.

[0068] The method comprises a step of moving a tailgate between an open position and a closed position for allowing a formed bale to be ejected from the compression chamber. The tailgate is at the open position when the tensioning arms are at the full bale position.

[0069] The method comprises a step of adjusting the pressure in the hydraulic cylinder to control the tension of the belts.

[0070] The method comprises a step of pressurizing the hydraulic cylinder according to a first predetermined pressure value during the opening of the tailgate. The method comprises a step of pressurizing the hydraulic cylinder according to a second predetermined pressure value during the closing of the tailgate. The first pressure value is smaller than the second pressure value. The first pressure is set so that there is a slippage in the belts in the open configuration.

[0071] In an example, the predetermined pressure values are variable.

[0072] In an example, the predetermined pressure values are modified in response to input values entered by the user.

[0073] The predetermined pressure values can be modified in response to a plurality of control parameters.

[0074] The control parameters may be representative of belt slippage.

[0075] The pressure in the hydraulic cylinder may be adjusted based on a plurality of predetermined setpoint values. The setpoint values for each layer of the bale may be determined while the bale is being formed.

[0076] The setpoint value of the pressure in the closing configuration is smaller than the maximum value of the predetermined setpoint values.

[0077] The value of the pressure in the hydraulic cylinder in the bale starting position may be equal to that of the opening configuration.

[0078] In an example, the plurality of predetermined setpoint values is set so that the maximum amount of pressure in the hydraulic cylinder is obtained when the bale is bound with a film or a net.

[0079] In an example, the tension of the belts is adjusted through a proportional valve.

[0080] In an example, the force exerted on the first and second arms towards the bale starting position is provided by an elastic unit which includes a fluid accumulator.

[0081] Preferably, the elastic unit is supplied with oil through a closed hydraulic circuit, different from the hydraulic circuit which supplies oil to the hydraulic actuator.

[0082] Brief description of the drawings

[0083] These and other features are more apparent from the following description of a preferred embodiment, illustrated purely by way of non-limiting example in the accompanying drawings, in which:

[0084] - Figure 1 shows a baler for making round bales according to one or more aspects of this disclosure;

[0085] - Figure 2 shows a part of the baler, which includes the tensioning belts;

[0086] - Figure 3 shows a perspective side view of the baler;

[0087] - Figure 4 shows an elastic unit of the tensioning system of the baler;

[0088] - Figures 5-10 show a hydraulic circuit of the baler, according to different embodiments;

[0089] - Figure 1 1 shows the trend in pressure as a function of operating steps.

[0090] Detailed description of preferred embodiments of the invention

[0091] With reference to the accompanying drawings, the numeral 1 denotes a baler for making round bales according to this invention. The baler 1 comprises a frame F. The frame F defines an internal volume. The baler 1 also includes a feed unit 2. The feed unit 2 is configured to collect agricultural products from the ground and to feed them to the baler 1 . The baler 1 also includes a compression chamber C. The compression chamber C is configured to compress the agricultural products to form the bale. The compression chamber C has a variable diameter. In the compression chamber C, the size of the bale formation zone increases as the bale forms in the compression chamber. The baler 1 comprises a plurality of guide rollers 3. The plurality of guide rollers (rollers) are located in the internal volume. In an example, the rollers of the plurality of guide rollers 3 are toothed. In an example, at least one of the guide rollers is movable so that the size of the compression chamber C can be increased. The plurality of guide rollers 3 includes a pair of infeed rollers 3E. The baler 1 may comprise a feed roller 7. The feed roller 7 is located between the exit O of the feed unit 2 and the infeed rollers 3E. The feed roller 7 is configured to push the agricultural products towards the compression chamber C to contribute to feeding the agricultural products towards the compression chamber. The baler 1 also includes a plurality of belts 4. The belts of the plurality of belts 4 are placed side by side in the internal volume. The belts of the plurality of belts 4 are wound around the guide rollers to define an endless looped path 5. The looped path 5 delimits the compression chamber flexibly. In addition, the guide rollers 3 are rotatable so as to drive the belts 4 round the looped path. In particular, each part of the plurality of belts 4 is stretched between two consecutive rollers 3. In an example, each belt of the plurality of belts 4 lies in a plane which is oriented longitudinally so that the plurality of belts 4, stretched between the plurality of rollers 3, are oriented along a longitudinal direction L. In an example, each belt of the plurality of belts is between 180 mm and 320 mm wide, for example approximately 280 mm wide with four or five belts. Preferably, each belt of the plurality of belts is 282 mm wide. In an example, the plurality of belts includes four belts. In an example, the compression chamber is 1230 mm wide (with four belts) or 1570 mm wide (with five belts). The plurality of belts 4 may include five belts. In the compression chamber C, the bale is formed between at least two consecutive rollers 3 which are sufficiently spaced apart to allow the belts 4 to be stretched taut between the two rollers 3. Thus, the plurality of belts 4 encloses the circumference of the bale being formed inside the compression chamber.

[0092] In particular, the belts 4 deform as the bale takes shape inside the compression chamber C. Thus, the belts 4 adapt to the shape of the bale being formed inside the compression chamber. In an example, an infeed portion EP of the looped path 5 between the infeed rollers 3E is transverse to the feed direction D. The infeed portion EP of the looped path 5 is located at the exit O of the feed unit 2 so that the hay comes into contact with the infeed portion EP of the looped path 5 the moment it enters the internal volume.

[0093] The baler 1 includes a tensioning system 6. The tensioning system 6 is configured to apply a tension to the belts 4 so as to generate a corresponding pressure on the agricultural products contained inside the compression chamber C. The tensioning system may include a first tensioning arm 601 and a second tensioning arm 602. The first and second tensioning arms are articulated to the frame F. The first and second tensioning arms are articulated to the frame F to move between a bale starting position, where the bale is at the initial stage of its formation, and a full bale position, where a complete bale is formed inside the compression chamber C. The tensioning arms apply a constant tension on the belts and release the amount of belt needed to increase the size of the bale inside the compression chamber.

[0094] In particular, the tensioning system 6 is configured to adjust the tension of the belts 4 until reaching a predefined tension value. The predefined tensioning value is selected by the operator. In an example, the baler 1 comprises a control unit.

[0095] The control unit is connected to the tensioning system 6. The control unit is programmed to automatically set the tension of the belts 4 to an initial value. The control unit is programmed to automatically set the tension of the belts 4 to an initial value, with the tensioning arms placed at the bale starting position. The control unit is also programmed to automatically increase belt tension to reach a predefined tension value responsive to a predetermined oscillation angle about an articulation point as the arms move upwards during the formation of the bale. The articulation point is the point where the tensioning arms 601 , 602 are articulated to the frame F of the baler 1. In other words, while the core of the bale is being formed in the initial step of bale formation, the control unit sets the tension of the belts to an initial value. The initial value is preferably near zero. As the core of the bale forms in the compression chamber C, the belts deform to adapt to the shape of the bale core and the tensioning arms move upwards. When the oscillation angle of the tensioning arms reaches a predetermined value, considered as the end of the step of core formation, the control unit increases the tension of the belts 4 to a predefined tensioning value. In an example, the baler 1 includes an angular sensor to detect the oscillation angle of the tensioning arms. Thus, through the sensor, which is associated with one or both of the arms, it is possible to detect the movement and the position of the arms, hence the diameter of the bale.

[0096] In an example, the control unit is configured to modify the tension of the belts in a range between a low value, a medium value and a high value. The control unit is configured to modify the tension of the belts responsive to predefined values selectable by the operator. Different belt tension values can be selected for the core of the bale, for the intermediate part of the bale, between the core and the outer part of the bale, and for the outer parts of the bale. For example, the predefined belt tension value may be low, medium or high. The control unit is also programmed to automatically set the tension of the belts 4 to an initial value that is lower than the low value. The belt tension is adjusted by operating actively on the arms through a system of actuators (for example, hydraulic cylinders 603, 604), described below.

[0097] Thus, the control unit is configured to adjust the pressure in the hydraulic cylinder according to a plurality of predetermined setpoint values. The setpoint values for each layer of the bale are determined while the bale is being formed.

[0098] In an example, the control unit is configured to modify the tension of the belts through a proportional valve 905.

[0099] The first tensioning arm 601 and the second tensioning arm 602 each have a first end 601 A, 602A and a second end 601 B, 602B. Both the first tensioning arm 601 and the second tensioning arm 602 are articulated to the frame F, respectively at the first ends 601 A, 602A thereof. In an example, the tensioning arms are each articulated to the frame in such a way that the arm is spaced from the plurality of guide rollers 3 relative to an advancing direction AD of the baler 1 .

[0100] Additionally, in an example, the tensioning arms 601 , 602 each have a first arm roller AR1 . The first arm roller AR1 is located at the second end 601 B, 602B of each of the tensioning arms 601 , 602. The tensioning arms each have a second arm roller AR2. The second arm roller AR2 is interposed between the first end 601 A, 602A and the second end 601 B, 602B of each tensioning arm 601 , 602. In particular, each tensioning arm has a lower half and an upper half. The lower half extends from a midpoint of each tensioning arm to the second end 601 B, 602B of each arm. The upper half of each tensioning arm extends from the midpoint to the first end 601 A, 602A. In an example, the second arm roller AR2 is located in the lower half, in proximity to the first arm roller AR1 . In an example, the first and second arm rollers AR1 , AR2 are configured to cooperate with the plurality of guide rollers 3 located at a height above the articulation point between the tensioning arms 601 , 602 and the frame F, where the belts of the plurality of belts 4 are wound. Additionally, the plurality of guide rollers 3 includes a first guide roller 301 . The plurality of guide rollers 3 includes a second guide roller 302. The plurality of guide rollers 3 includes a third guide roller 303. In an example, the first, second and third rollers are located at a height above the articulation point between the tensioning arms 601 , 602 and the frame F. The first arm roller and the second arm roller are configured to cooperate with the first, second and third rollers 301 , 302, 303 in such a way as to stretch the belts 4 between the first guide roller and the first arm roller; the first arm roller and the second guide roller; the second guide roller and the second arm roller; the second arm roller and the third guide roller.

[0101] Additionally, the second and third guide rollers 302, 303 are interposed between the first end and the second end of the arm along the advancing direction.

[0102] The infeed portion of the belt is stretched only between the infeed rollers 3E and is not wound around the first and second arm rollers AR1 , AR2.

[0103] According to an aspect of this disclosure, the tensioning system 6 includes an actuator 603, 604. The actuator is associated with the first or the second tensioning arm 601 , 602. The first and second tensioning arms perform an upward movement while the bale is being formed and a downward movement after the bale is unloaded. The actuator 603, 604 is configured to adjust the movement of the first and second arms so as to adjust the tension of the belts according to given, predefined values for each layer of the bale. In an example, the first and second tensioning arms 601 , 602 are coupled and positionable in synchrony with each other.

[0104] In an example, the tensioning system 6 includes an elastic unit associated with the first or the second arm and configured to force the arms towards the bale starting position.

[0105] The actuator 603, 604 includes a hydraulic cylinder. The baler includes a hydraulic circuit 9 configured to feed actuating oil to the hydraulic cylinder of the actuator 603. The actuator is configured to apply resistance to the tensioning arms 601 , 602 as they start moving upwards while the bale is being formed inside the compression chamber. The hydraulic cylinder has a cylindrical pipe. The cylindrical pipe has a piston connected to a conrod. The piston divides the pipe into two cylindrical chambers: an upper chamber (conrod side) and a lower chamber (piston side). At the bale starting position, when the tensioning arms move down, the upper chamber is full of fluid. As the tensioning arms gradually start moving up, the piston rises and the fluid is slowly removed from the upper chamber through the proportional valve. Thus, the tensioning arms are moved upwards by the pressure exerted by the bale being formed inside the compression chamber. The proportional valve 905 and the control unit allow increasing belt tension thanks to the resistance which the actuator 603 applies to the upward movement of the tensioning arms. It should be noted that the belt tension determines the density of the bale. Additionally, a different tension value can be selected for each layer of the bale. For example, the core of the bale, the intermediate layer and the outer layer may have the same tension value or different values.

[0106] The baler also includes a tailgate. The tailgate which is movable between a closed position, during bale formation inside the compression chamber, and an open position, for ejecting a formed bale from the compression chamber. The tailgate is at the open position when the tensioning arms are at the full bale position. The tailgate is moved between the open position and the closed position by an actuator. The actuator of the tailgate may be electric or hydraulic. When the tailgate actuator is hydraulic, the tailgate is connected to a pair of cylinder-piston units 901 which allow opening and closing the tailgate. In an example, therefore, the tailgate actuator is powered by the hydraulic circuit of the baler. Each of the cylinder-piston units includes a pipe with a conrod and a piston. The pipe of the cylinderpiston units 901 , like the pipe of the hydraulic cylinders 603, 604 of the tensioning system includes a piston side 901 A and a conrod side 901 B. The pipe of the cylinder-piston units 901 is full of a fluid. The tailgate opens to unload the formed bale from the compression chamber. Additionally, the hydraulic circuit 9 is also connected to the tractor TR to which the baler 1 can be hitched. The hydraulic cylinder (actuator) 603, 604 of the tensioning system 6 is connectable to the cylinder-piston units 901 of the tailgate through the hydraulic circuit 9 between the tractor and the baler. The hydraulic circuit is illustrated schematically in Figure 1 1 . Additionally, the hydraulic circuit 9 includes a hydraulic control unit 900 to regulate the fluid in the hydraulic circuit 9. In that schematic representation, when the tailgate opens, the piston side 901 A of the cylinder-piston units 901 of the tailgate and the piston side of the hydraulic cylinder 603 of the tensioning system are filled with fluid (oil), pushing the conrod upwards and discharging oil from the conrod side 901 B (conrod, or cylinder stem) of the cylinder-piston units 901 . Consequently, pressure is applied to a first connecting line C1 that connects the hydraulic power take-off of the tractor TR to the first intake point 902 of the hydraulic control unit 900 and the pressure increases on one side of the circuit 9. In this case, therefore, the pressure P1 of the first connecting line C1 is higher than the second pressure P2 of a second connecting line C2 that connects the hydraulic power take-off of the tractor to a second intake point 903 of the hydraulic control unit 900. The second pressure is, for example, 240 bar or less; more generally speaking, it is less than or equal to the maximum permitted pressure value of the proportional valve. At the same time, when the oil is transferred to the piston side of the cylinder-piston units 901 of the tailgate and of the hydraulic cylinder 603, a plurality of regulator valves 904 are activated to open the connecting line whose pressure is the lower (the second connecting line C2). In particular, the oil, discharged from the conrod side of the cylinder-piston units of the tailgate and of the hydraulic cylinder 603 of the tensioning system travels along the connecting line with the lower pressure (the second connecting line C2). The hydraulic circuit 9 may include a bypass valve 908. As explained above, the control unit is programmed to automatically set the tension of the belts to an initial value, when the tensioning arms are at the bale starting position. The initial tension value may be near zero. In particular, when the tensioning arms are at the bale starting position and the agricultural products are entering the compression chamber to form the bale (preliminary step to form the core of the bale), the control unit generates the command to open the bypass valve 908. Consequently, the conrod side and the piston side of the hydraulic cylinder 603 of the tensioning system 6 are connected through the open bypass valve 908 to allow the fluid to pass from one end to the other of the pipe of the hydraulic cylinder 603 through the bypass valve. In this case, the fluid of the conrod side and the fluid of the piston side of the cylinder 603 are in equilibrium so as to not to exert any pressure on the tensioning arms. Thus, the tensioning arms move upwards only under the action of the agricultural products which come into contact with the infeed portion of the belts 4 as they enter the compression chamber. When the core of the bale reaches a predetermined diameter, the preliminary step of forming the core of the bale is considered over. At the end of the preliminary step of forming the core of the bale, the control unit generates the command to close the bypass valve 908 and to open the proportional valve 905. Thus, the fluid on the conrod side of the hydraulic cylinder 603 passes through the proportional valve 905.

[0107] As mentioned above, oil discharge from the conrod side of the hydraulic cylinder is regulated by the proportional valve 905. Thus, as the tensioning arms 601 , 602 move upwards while the bale is being formed, the oil (that is, the fluid) is discharged from the conrod side of the pipe of the hydraulic cylinder 603 in response to a predetermined resistance which must oppose the upward movement of the tensioning arms so as to tension the belts 4 as needed to provided the required tension on the bale core and on the different layers of the bale. When the predetermined resistance is reached, the proportional valve 905 closes in order to stop fluid discharge from the conrod side of the hydraulic cylinder 603. Then, on account of the upward movement of the tensioning arm, the conrod rises and the pressure on the conrod side of the hydraulic cylinder increases. The proportional valve is then re-opened to regulate oil discharge from the conrod side, hence the tensioning level of the arms.

[0108] Thus, the initial tension value of the belts is given by the bypass valve 908; in addition, the belt tension value, which determines the density of each layer of the bale, is given by the proportional valve 905 in response to a predefined value selected by the operator.

[0109] When the tiltable tailgate closes, the oil is transferred to the conrod side of the piston-cylinder units of the tailgate and to the conrod side of the hydraulic cylinders (actuators) of the tensioning system. Consequently, pressure is applied to the second connecting line C2 and so the pressure P2 of the second connecting line is higher than the pressure P1 of the first connecting line. At the same time, oil is drawn from the piston side. The oil which is transferred to the conrod side of the piston-cylinder units 901 can be regulated by an adjustable choke valve 906. In addition, the oil which is transferred to the conrod side of the hydraulic cylinder 603 can be regulated by a fixed choke valve 907. It should be noted that while the oil fills the conrod side of the hydraulic cylinder, the proportional valve 905 and the bypass valve are disabled.

[0110] The tensioning system includes an elastic unit. The elastic unit is associated with the first or the second arm and is configured to force the arms towards the bale starting position.

[0111] In an example, the elastic unit comprises a fluid accumulator A. The fluid accumulator has a gas volume. The accumulator functions in response to the movement of the arms in order to take the tensioning arms back to the bale starting position after the bale has been unloaded, so that in the absence of any external force, the tensioning arms are kept in the bale starting position. In this example, the elastic unit has a hydraulic circuit to feed oil to a fluid side of the accumulator.

[0112] Preferably, the elastic unit has a closed hydraulic circuit which is separate from the hydraulic circuit.

[0113] In an example, the accumulator A is connected to a passive piston-cylinder unit 605 to form an elastic unit 606.

[0114] Alternatively, the accumulator is integrated in a passive piston-cylinder unit to form an elastic unit 606.

[0115] In particular, the elastic unit is configured to return the tensioning arms 601 , 602 to the bale starting position after the bale has been unloaded. Thus, in the absence of an external force (for example, a force exerted on the tensioning arms while the bale is being formed), the elastic unit keeps the tensioning arm at the lowered position (bale starting position). In an example, the elastic unit has a closed hydraulic circuit in which a specific quantity of pressurized fluid flows between the passive piston-cylinder unit 605 and the accumulator A. The pressurized fluid flows between the passive piston-cylinder unit 605 and the accumulator does not therefore enter the hydraulic circuit 9. The passive piston-cylinder unit 605 comprises a pipe and a piston P which is connected to a conrod and which divides the pipe into two cylindrical chambers. One of the chambers of the pipe of the passive piston-cylinder unit 605 is connected to the accumulator A to form the closed hydraulic circuit. The other chamber is full of air. The accumulator sucks the fluid in while the tensioning arms move upwards under the action of the bale being formed; as a result, the pressure P3 increases and the gas is compressed. When the bale is unloaded, the gas expands, causing the fluid to enter the chamber of the passive piston-cylinder unit 605 under pressure; consequently, the piston is lowered and with it the tensioning arms move down to the bale starting position. When the fluid is made to enter the chamber of the passive piston-cylinder unit 605 and the piston P is lowered, the air inside the second chamber of the passive piston-cylinder unit 605 is exhausted to the outside. It is also possible to change the fluid of the hydraulic circuit though an exhaust point.

[0116] The hydraulic accumulator has a gas volume. Additionally, the operation of the hydraulic accumulator occurs in response to the movement of the tensioning arms 601 , 602 so that the gas expands when the tensioning arms move downwards and the actuator is retracted, while the gas is compressed when the actuator is extended and the arms move upwards, or vice versa. In an example, the accumulator A is a diaphragm accumulator. In the accumulator, a diaphragm M is used to separate the fluid side FS from the gas side GS of the accumulator. In particular, the diaphragm acts as an elastic body which compresses the gas when the accumulator is filled with fluid.

[0117] In particular, in the diaphragm accumulator, a diaphragm is used as a partition between the fluid side and the gas side of the accumulator. The diaphragm can deform if pressed by the gas or by the fluid. In another example, the actuator may have a rigid partition to separate the gas from the fluid. The partition can be moved by an actuator towards or away from the gas side in order to compress or expand the gas.

[0118] The hydraulic cylinder is pressurized at a first predetermined pressure value when the tailgate is at the closed position and when it moves from the open position to the closed position. The hydraulic cylinder is pressurized at a second predetermined pressure value when the tailgate moves from the closed position to the open position during the step of opening the tailgate. The pressure is changed when it is detected (through a sensor that is sensitive to the angle of inclination of the belt tensioning arms, or by processing a signal) that the tailgate starts closing and for the entire duration of the tailgate closing movement. The first pressure (in the step of opening the tailgate) is less then the second pressure (in the step of closing the tailgate) and is set so that there is a slippage in the belts in the open configuration.

[0119] As explained above, the hydraulic cylinder is pressurized by the oil from the hydraulic circuit.

[0120] The first and second predetermined pressure values are variable. For example, these values can be modified in response to the values entered by the user, or in response to a plurality of control parameters such as, for example, belt slippage.

[0121] The pressure in the hydraulic cylinder is based on a plurality of predetermined setpoint values, the setpoint values being determined for each layer of the bale during bale formation.

[0122] As explained above, the tension of the belts can be modified during different steps in the formation of the bale. The tension of the belts is varied by changing the pressure of the hydraulic cylinder.

[0123] The pressure in the hydraulic cylinder is based on a plurality of predetermined setpoint values which are determined for each layer of the bale during bale formation.

[0124] For example, the initial pressure value is a value near zero and may be up to 50 bar during the first step of forming the core of the bale, preferably up to a diameter of 75 cm. This pressure may increase in the second step of forming the core of the bale, for example, up to a diameter of 90 cm. The pressure may remain the same in the step of forming the intermediate layer, for example up to a diameter of 85 cm. The pressure in the hydraulic cylinder may increase in the step of forming the outer layer of the bale. Once the bale is completely formed, it can be bound in a film or net. Therefore, the baler may comprise a binding device.

[0125] The binding device may be according to one or more aspects of patent application 102023000010374, in the name of the present Applicant and incorporated herein by reference.

[0126] The pressure of the cylinder may be increased during the step of binding the bale. Next, the pressure in the cylinder is reduced to the second pressure value in order to open the tailgate. The second value may be equal to the initial pressure value, that is, the near-zero value. Next, the pressure is increased while the tailgate is closing, until reaching the first pressure value. The first pressure value may be lower than the maximum value of the predetermined setpoint values during the step of forming the bale and the step of binding it.

[0127] Preferably, the plurality of predetermined setpoint values is set so that the maximum amount of pressure in the hydraulic cylinder is obtained in a binding step in which the formed bale is wrapped in a film or a net. The first pressure value, while the tailgate is closing, may be equal to the value of the pressure during the formation of the intermediate layer of the bale.

[0128] In an example, the tensioning system includes a second actuator 604. In this example, the first and second actuators are associated with the first and second tensioning arms 601 , 602, respectively. It should be noted that the features described above in connection with the first actuator also apply to the second actuator, and the second actuator is connected to the hydraulic circuit in the same way as explained for the actuator 603.

[0129] The elastic unit may be provided with a single accumulator A connected to a respective passive piston-cylinder unit in combination with a single actuator 603, or with a pair of accumulators A connected to respective passive piston-cylinder units in combination with a single actuator 603, or with a single accumulator A connected to a respective passive pistoncylinder unit in combination with a pair of actuators 603, 604, or with a pair of passive piston-cylinder units in combination with a pair of actuators 603, 604, where only one passive piston-cylinder unit is connected to a respective accumulator A, or with a pair of accumulators connected to respective passive piston-cylinder units in combination with a pair of actuators 603, 604.

[0130] It should be noted that when two accumulators are provided, the second accumulator is the same as the accumulator A, described above, and is connected to the closed hydraulic circuit of the accumulator.

[0131] In another possible solution, no bypass valve is used, not even in the initial step of forming the bale core. In this example, the pressure is adjusted solely through the proportional valve.

[0132] In the case where the pressure is adjusted solely through the proportional valve without using a 0-bar / bypass valve, the possible main advantage is that of producing a bale core which is less dense and bale rotation can be more readily initiated.

[0133] Figure 1 1 shows an example of a strategy whereby the pressure in the actuators 603, 604 is varied during different operating steps of the baler.

[0134] For example, the operating steps of the baler are the following: a) forming the bale (while the baler advances along the field), for example, from an instant to to an instant ts; b) binding the bale, for example, from an instant ts to an instant te; c) opening the tailgate to eject the bale, for example, from an instant teto an instant t?; d) closing the tailgate, for example, from an instant t? to an instant ts.

[0135] At the end of step (a), the baler is stopped and steps (b) and (c), and preferably step (d) too, are carried out with the baler at a standstill.

[0136] In the context of step (a) of forming the bale, the following sub-steps can be identified: a1) forming the inner part of the bale (the core of the bale), for example, from the instant to to an instant t2; a2) forming the central, intermediate part of the bale, for example, from the instant t2 to an instant ts; a3) forming the outer part of the bale, for example, from the instant t3 to an instant t4; a4) final step of forming the bale, for example, from the instant t4 to the instant ts.

[0137] In the context of sub-step (a1 ) of forming the inner part of the bale, there may be an initial time interval constituting a step of "booting" the baler, for example from the instant to to an instant ti, where ti is temporally located between to and t3.

[0138] In an example, the pressure in the actuators 603, 604 is controlled to adopt the following trend:

[0139] - value P0 during the booting step, where Po is 0 bar or near 0 bar;

[0140] - in the time interval between ti and t2, during the step of forming the core of the bale, values greater than Po, preferably increasing to a value Pi ;

[0141] -P2 (where P2 > Pi ), during the step (a2) of forming the intermediate part of the bale;

[0142] -P3 (where P3 P2), during the step (a3) of forming the outer part of the bale;

[0143] -P4 (where P4 > P3), during the final step (a4) of forming the bale;

[0144] -P5 (where P5 P4), during the step (b) of binding the bale;

[0145] - Pe (where Pe < Pi), during the step (c) of opening the tailgate;

[0146] - P7 (where P7 > Pe and P7 < P5), during the step (d) of closing the tailgate. Preferably, P5 is the maximum pressure applied to the actuator 603, 604.

[0147] Preferably, P7 is an adjustable value, settable either manually by the user through an interface, or automatically by the control unit of the baler.

[0148] In an example, the control unit detects the changeover from one step to another of forming the bale, based on a measurement or estimate of the diameter of the bale.

[0149] In an example, the control unit calculates the moment when it is necessary to pass to the steps of opening and then closing the tailgate, based on the detection of the angle of inclination of the tensioning arms (for example, through a sensor mounted on the arms).

[0150] Preferably, P7 is greater than P2 and less than P4. Preferably, one or more of the values from Pi to P7, are adjustable values, settable either manually by the user through an interface, or automatically by the control unit of the baler, for example, depending on other pressure setpoint values (for example, P3 is derived by the control unit from P2, or P7 is derived by the control unit from P4).

Claims

CLAIMS1. A baler (1 ) for forming round bales of agricultural products, including:- a frame (T) providing an internal volume;- a compression chamber (C) for compressing the agricultural products to form the bale,- a plurality of guide rollers (3) placed inside the internal volume;- a plurality of belts (4) placed side by side in the internal volume and wound around the guide rollers so as to define an endless loop (5), the loop being deformable for delimiting the compression chamber;- a tensioning system (6) configured for applying a tension to the belts so as to generate a corresponding pressure on the agricultural products contained inside the compression chamber, the tensioning system including: a first tensioning arm (601 ) and a second tensioning arm (602) articulated to the frame, to move between a bale starting position, where the formation of the bale starts, and a full bale position, where a complete bale is formed inside the compression chamber; an actuator (603), including a hydraulic cylinder, associated with the first or the second arm and configured to apply a force to the first and the second arm to adjust the tension of the belts, an elastic unit associated with the first or the second arm and configured to force the arms towards the bale starting position,- a hydraulic circuit (9) configured to feed actuating oil to the hydraulic cylinder;- a tailgate movable between an open position and a closed position for allowing a formed bale to be ejected from the compression chamber, wherein the tailgate is at the open position with the tensioning arms at the full bale position;- a control unit for adjusting the pressure in the hydraulic cylinder to control the tensioning of the belts, wherein the control unit is configured to pressurize the hydraulic cylinder witha first predetermined pressure value in an opening configuration, between the open position and the closed position, a second predetermined pressure value in a closing configuration, between the closed position and the open position, wherein the first pressure value is smaller than the second pressure value and is set so that there is a slippage in the belts in the open configuration.

2. The baler (1 ) according to claim 1 , wherein the predetermined pressure values are variable.

3. The baler (1 ) according to claim 2, wherein the control unit is configured to modify the predetermined pressure values in response to input values input by the user.

4. The baler (1 ) according to claim 2, wherein the control unit is configured to modify the predetermined pressure values in response to a plurality of control parameters.

5. The baler (1 ) according to claim 4, wherein the control parameters are representative of the slippage of the belts.

6. The baler (1 ) according to any of the previous claims, wherein the control unit is configured to adjust the pressure in the hydraulic cylinder according to a plurality of predetermined setpoint values, the setpoint values being determined for each layer of the bale during the bale formation.

7. The baler (1 ) according to claim 6, wherein the setpoint value of the pressure in the closing configuration is smaller than the maximum value of the predetermined setpoint values.

8. The baler (1 ) according to claim 6 or 7, wherein the value of the pressure in the hydraulic cylinder in the bale starting position is equal to that of the opening configuration.

9. The baler (1 ) according to any of the previous claims from 6 to 8, wherein the plurality of predetermined setpoint values is set so that the maximum amount of pressure in the hydraulic cylinder is obtained in a binding step in which the formed bale is wrapped in a film or a net.

10. The baler (1 ) according to any of the previous claims wherein the secondpressure value is higher than a pressure adopted in an initial step of bale formation and lower than a pressure adopted in a final step of bale formation.

11. The baler (1 ) according to any of the previous claims, wherein the control unit is configured to adjust the tensioning of the belts through a proportional valve (905).

12. The baler (1 ) according to any of the previous claims wherein the elastic unit includes a fluid accumulator (A), wherein the fluid accumulator has a gas volume, the accumulator functioning responsive to the movement of the arms in order to take the tensioning arms back to the bale starting position after the bale release, so that in absence of any external force, the tensioning arms are kept in the bale starting position, the elastic unit having a hydraulic circuit for feeding oil to a fluid side of the accumulator.

13. The baler (1 ) according to claim 12, wherein the elastic unit has a closed hydraulic circuit which is separate from said hydraulic circuit (9).

14. A method for forming round bales comprising the following steps:- providing a baler (1 ) with a plurality of guide rollers (3) placed inside an internal volume of the baler;- placing a plurality of belts (4) side by side in the internal volume and winding them around the guide rollers so as to define an endless loop, the loop being deformable for delimiting a compression chamber (C);- applying a tension to the belts so as to generate a corresponding pressure on the agricultural products contained inside the compression chamber;- moving a pair of tensioning arms (601 , 602) between a bale starting position, where the formation of the bale starts, and a full bale position, where a complete bale is formed inside the compression chamber;- applying a force to the first and the second arm to adjust the tension of the belts through a respective actuator (603, 604) which includes a hydraulic cylinder;- forcing the arms towards the bale starting position through an elastic unit associated with the first or the second arm;- feeding actuating oil to the hydraulic cylinder through a hydraulic circuit (9);- moving a tailgate between an open position and a closed position for allowing a formed bale to be ejected from the compression chamber, wherein the tailgate is at the open position with the tensioning arms at the full bale position;- adjusting the pressure in the hydraulic cylinder to control the tensioning of the belts;- pressurizing the hydraulic cylinder according to a first predetermined pressure value during the opening of the tailgate, and pressurizing the hydraulic cylinder according to a second predetermined pressure value during the closing of the tailgate, wherein the first pressure value is smaller than the second pressure value and is set so that there is a slippage in the belts in the open configuration.

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