APPARATUS AND METHOD FOR FORMING A ROUND BALE WITH A TENSIONED PRESSING MEANS

Abstract

An apparatus and a method are disclosed for forming a cylindrical bale in a bale forming chamber. An endless pressing mechanims partially surrounds the bale forming chamber. A first tensioning member and a second tensioning member together tension the pressing mechanism by at least two guiding elements. A tensioning actuator is biased to pivot the second tensioning member away from the first tensioning member.

Claims

1. A bale forming apparatus for forming a round-cylindrical bale from loose material, wherein the bale forming apparatus comprises: a bale former comprising an endless pressing mechanism; a tensioning arrangement for the pressing mechanism; and a casing comprising a moveable casing part, wherein the tensioning arrangement comprises: a tensioning actuator; a first pivotally mounted tensioning member comprising at least one first guiding element; and a second pivotally mounted tensioning member comprising at least one second guiding element, wherein the moveable casing part is moveable between a bale forming position and a bale ejecting position, wherein the casing with the moveable casing part being in the bale forming position surrounds a bale forming chamber, wherein the bale former is arranged to form the cylindrical bale in the bale forming chamber surrounded by the casing, wherein the casing with the moveable casing part being in the bale ejecting position provides an aperture for ejecting the formed bale out of the bale forming chamber, wherein the pressing means mechanism is guided around the first guiding element of the first tensioning member and around the second guiding element of the second tensioning member, wherein the tensioning actuator tends to pivot the second tensioning member away from the first tensioning member, thereby applying a tensioning force onto the pressing mechanism, wherein the bale forming apparatus further comprises a bale pushing element, wherein the bale pushing element is mechanically connected with the first tensioning member, wherein the tensioning arrangement is arranged such that pivoting the second tensioning member away from the first tensioning member pivots the first tensioning member towards the bale in the bale forming chamber and causes the connected bale pushing element to contact the bale and to push the bale towards the moveable casing part.

2. A bale forming apparatus for forming a round-cylindrical bale from loose material, wherein the bale forming apparatus comprises: a bale former comprising an endless pressing mechanism; a tensioning arrangement for the pressing mechanism; and a casing comprising a moveable casing part, wherein the tensioning arrangement comprises: a tensioning actuator; a first pivotally mounted tensioning member comprising at least one first guiding element; and a second pivotally mounted tensioning member comprising at least one second guiding element, wherein the moveable casing part is moveable between a bale forming position and a bale ejecting position, wherein the casing with the moveable casing part being in the bale forming position surrounds a bale forming chamber, wherein the bale former is arranged to form the cylindrical bale in the bale forming chamber surrounded by the casing, wherein the casing with the moveable casing part being in the bale ejecting position provides an aperture for ejecting the formed bale out of the bale forming chamber, wherein the pressing mechanism is guided around the first guiding element of the first tensioning member and around the second guiding element of the second tensioning member, wherein the tensioning actuator tends to pivot the second tensioning member away from the first tensioning member, thereby applying a tensioning force onto the pressing mechanism, wherein the second tensioning member comprises a lever member pivotally mounted at the casing, wherein the second guiding element is mounted at a free end of the lever member, wherein the tensioning actuator is connected with the lever member for pivoting with respect to the lever member around an actuator pivoting axis, wherein the tensioning actuator tends to pivot the lever member with respect to the casing around a lever pivoting axis, and wherein the actuator pivoting axis is positioned between the second guiding element and the lever pivoting axis.

3. A bale forming apparatus for forming a round-cylindrical bale from loose material, wherein the bale forming apparatus comprises: a bale former comprising an endless pressing mechanism; a tensioning arrangement for the pressing mechanism; and a casing comprising a moveable casing part, wherein the tensioning arrangement comprises: a tensioning actuator; a first pivotally mounted tensioning member comprising at least one first guiding element; and a second pivotally mounted tensioning member comprising at least one second guiding element, wherein the moveable casing part is moveable between a bale forming position and a bale ejecting position, wherein the casing with the moveable casing part being in the bale forming position surrounds a bale forming chamber, wherein the bale former is arranged to form the cylindrical bale in the bale forming chamber surrounded by the casing, wherein the casing with the moveable casing part being in the bale ejecting position provides an aperture for ejecting the formed bale out of the bale forming chamber, wherein the pressing mechanism is guided around the first guiding element of the first tensioning member and around the second guiding element of the second tensioning member, wherein the tensioning actuator tends to pivot the second tensioning member away from the first tensioning member, thereby applying a tensioning force onto the pressing mechanism, wherein the bale forming apparatus comprises a diameter sensor comprising a distance sensor and the tensioning arrangement comprises a first part connected with or belonging to the first tensioning member and a second part connected with the or belonging to the second tensioning member, wherein the second part is moveable with respect to the first part, wherein the distance sensor is arranged to measure the distance between the first part and the second part, and wherein the diameter sensor is arranged to calculate the measured diameter depending on the measured distance between the two parts.

4. The bale forming apparatus according to claim 1, wherein the bale forming apparatus is arranged such that the tensioning actuator tends to pivot the second tensioning member away from the first tensioning member in both positions of the moveable casing part.

5. The bale forming apparatus according to claim 1, wherein the endless pressing mechanism tends to apply pressure onto lose material contained in the bale forming chamber, thereby forming under pressure the bale in the bale forming chamber surrounded by the casing, and wherein the endless pressing mechanism tends to pivot the second tensioning member against the force of the tensioning actuator towards the first tensioning member.

6. The bale forming apparatus according to claim 1, wherein the casing comprises a further casing part, wherein the moveable casing part is mounted for being moved with respect to the further casing part into the bale ejecting position, and wherein the first tensioning member is pivotally connected with the further casing part such that the force of gravity tends to pivot the first tensioning member from angularly above towards a bale in the bale forming chamber.

7. The bale forming apparatus according to claim 1, characterized in wherein the tensioning actuator is pivotally connected with the first tensioning member and is pivotally connected with the second tensioning member.

8. The bale forming apparatus according to claim 1, wherein the bale forming apparatus comprises a distance sensor, and wherein the distance sensor is arranged to measure a value indicative of the distance between the two guiding elements.

9. The bale forming apparatus according to claim 1, wherein the pressing mechanism being guided around both tensioning members tends to pivot the second tensioning member against the force of the tensioning actuator towards the first tensioning member, wherein the bale forming apparatus is arranged such that the pressing mechanism surpasses the force of the tensioning actuator as long as the moveable casing part is in the bale forming position, and wherein the tensioning actuator surpasses the force of the pressing mechanism if the moveable casing part is in the bale ejecting position.

10. The bale forming apparatus according to claim 1, wherein the second tensioning member is positioned above the first tensioning member, wherein the tensioning actuator tends to pivot the second tensioning member into a substantially vertical orientation when the moveable casing part is in the bale ejecting position.

11. A bale forming method for forming a round-cylindrical bale from loose material, wherein the method is performed by using a bale forming apparatus comprising: a bale former comprising an endless pressing means mechanism; a tensioning arrangement for the pressing mechanism; and a casing comprising a moveable casing part, wherein the moveable casing part is moveable between a bale forming position and a bale ejecting position, wherein the tensioning arrangement comprises: a tensioning actuator; a first pivotally mounted tensioning member; and a second pivotally mounted tensioning member, wherein the pressing mechanism is guided around a first guiding element of the first tensioning member and around a second guiding element of the second tensioning member, wherein the method comprises: a bale forming phase, and a subsequent bale ejecting phase, wherein in the bale forming phase the steps are performed that: the casing with the moveable casing part being in the bale forming position surrounds a bale forming chamber; loose material is injected into the bale forming chamber; the tensioning arrangement tensions the endless pressing mechanism; and the bale former comprising the tensioned endless pressing means applies pressure onto the loose material contained in the bale forming chamber and forms under pressure the increasing cylindrical bale from the contained loose material in the bale forming chamber, wherein in the bale ejecting phase the steps are performed that: the moveable casing part is moved into the bale ejecting position such that an aperture is provided; and the bale is ejected out of the bale forming chamber through this aperture, wherein the further steps are performed that: the tensioning actuator tends to pivot the second tensioning member away from the first tensioning member; and pivoting the second tensioning member away from the first tensioning member applies a tension onto the pressing mechanism, wherein the first tensioning member is mechanically connected with a bale pushing element, wherein the bale ejecting phase comprises the additional step that the tensioning actuator pivots the first tensioning member away from the second tensioning member, and wherein pivoting the first tensioning member away from the second tensioning member causes the bale pushing element to come or to stay in contact with the bale and to push the bale towards the moveable casing part.

12. A bale forming method for forming a round-cylindrical bale from loose material, wherein the method is performed by using a bale forming apparatus comprising a bale former comprising an endless pressing mechanism; a tensioning arrangement for the pressing mechanism; and a casing comprising a moveable casing part, wherein the moveable casing part is moveable between a bale forming position and a bale ejecting position, wherein the tensioning arrangement comprises: a tensioning actuator; a first pivotally mounted tensioning member; and a second pivotally mounted tensioning member, wherein the pressing mechanism is guided around a first guiding element of the first tensioning member and around a second guiding element of the second tensioning member, wherein the method comprises: a bale forming phase; and a subsequent bale ejecting phase, wherein in the bale forming phase the steps are performed that: the casing with the moveable casing part being in the bale forming position surrounds a bale forming chamber; loose material is injected into the bale forming chamber; the tensioning arrangement tensions the endless pressing mechanism; and the bale former comprising the tensioned endless pressing means applies pressure onto the loose material contained in the bale forming chamber and forms under pressure the increasing cylindrical bale from the contained loose material in the bale forming chamber, wherein in the bale ejecting phase the steps are performed that: the moveable casing part is moved into the bale ejecting position such that an aperture is provided; and the bale is ejected out of the bale forming chamber through this aperture, wherein the further steps are performed that: the tensioning actuator tends to pivot the second tensioning member away from the first tensioning member; and pivoting the second tensioning member away from the first tensioning member applies a tension onto the pressing mechanism, wherein the second tensioning member comprises a lever member pivotally mounted at the casing, wherein the second guiding element is mounted at a free end of the lever member, wherein the tensioning actuator is pivotally connected with the lever member, and the step that the tensioning actuator tends to pivot the second tensioning member away from the first tensioning member comprises the step that the lever member tends to pivot with respect to the casing around a lever pivoting axis and the tensioning actuator tends to pivot with respect to the lever member around an actuator pivoting axis, wherein the actuator pivoting axis is positioned between the second guiding element and the lever pivoting axis.

13. A bale forming method for forming a round-cylindrical bale from loose material, wherein the method is performed by using a bale forming apparatus comprising: a bale former comprising an endless pressing mechanism; a tensioning arrangement for the pressing mechanism; and a casing comprising a moveable casing part, wherein the moveable casing part is moveable between a bale forming position and a bale ejecting position, wherein the tensioning arrangement comprises: a tensioning actuator, a first pivotally mounted tensioning member; and a second pivotally mounted tensioning member, wherein the pressing mechanism is guided around a first guiding element of the first tensioning member and around a second guiding element of the second tensioning member, wherein the method comprises: a bale forming phase; and a subsequent bale ejecting phase, wherein in the bale forming phase the steps are performed that: the casing with the moveable casing part being in the bale forming position surrounds a bale forming chamber; loose material is injected into the bale forming chamber; the tensioning arrangement tensions the endless pressing mechanism; and the bale former comprising the tensioned endless pressing means applies pressure onto the loose material contained in the bale forming chamber and forms under pressure the increasing cylindrical bale from the contained loose material in the bale forming chamber, wherein in the bale ejecting phase the steps are performed that: the moveable casing part is moved into the bale ejecting position such that an aperture is provided; and the bale is ejected out of the bale forming chamber through this aperture, wherein the further steps are performed that: the tensioning actuator tends to pivot the second tensioning member away from the first tensioning member; and pivoting the second tensioning member away from the first tensioning member applies a tension onto the pressing means, wherein the tensioning arrangement comprises: a first part connected with the or belonging to the first tensioning member; and a second part connected with the or belonging to the second tensioning member, wherein in the bale forming phase the further steps are performed that a value indicative of the distance between the first part and the second part is measured and the diameter of the bale is automatically calculated depending on the measured distance.

14. The bale forming method according to claim 11, wherein in the bale forming phase the further steps are performed that: the loose material applies a tensioning force onto the pressing mechanism; the pressing mechanism subjected to this tensioning force applies a pivoting force onto the tensioning members; and the pivoting force surpasses the force of the tensioning actuator and pivots the second tensioning member against the force of the tensioning actuator towards the first tensioning member, and wherein in the bale ejecting phase the further steps are performed that the tensioning actuator surpasses the pivoting force of the pressing means and pivots the second tensioning member against the pivoting force of the pressing means away from the first tensioning member.

15. The bale forming method according to claim 11, wherein the second tensioning member is positioned above the first tensioning member, and wherein the bale ejecting phase comprises the step that the tensioning actuator pivots the second tensioning member into a substantially vertical position.

16. The bale forming apparatus according to claim 2, wherein the bale forming apparatus is arranged such that the tensioning actuator tends to pivot the second tensioning member away from the first tensioning member in both positions of the moveable casing part.

17. The bale forming apparatus according to claim 3, wherein the bale forming apparatus is arranged such that the tensioning actuator tends to pivot the second tensioning member away from the first tensioning member in both positions of the moveable casing part.

18. The bale forming apparatus according to claim 2, wherein the endless pressing mechanism tends to apply pressure onto lose material contained in the bale forming chamber, thereby forming under pressure the bale in the bale forming chamber surrounded by the casing, and wherein the endless pressing mechanism tends to pivot the second tensioning member against the force of the tensioning actuator towards the first tensioning member.

19. The bale forming apparatus according to claim 3, wherein the endless pressing mechanism tends to apply pressure onto lose material contained in the bale forming chamber, thereby forming under pressure the bale in the bale forming chamber surrounded by the casing, and wherein the endless pressing mechanism tends to pivot the second tensioning member against the force of the tensioning actuator towards the first tensioning member.

20. The bale forming apparatus according to claim 4, wherein the endless pressing mechanims tends to apply pressure onto lose material contained in the bale forming chamber, thereby forming under pressure the bale in the bale forming chamber surrounded by the casing, and wherein the endless pressing mechanism tends to pivot the second tensioning member against the force of the tensioning actuator towards the first tensioning member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0093] FIG. 1 shows a round baler according to the invention with an empty bale forming chamber;

[0094] FIG. 2 shows five lever arms between the tensioning actuator and three guiding rollers;

[0095] FIG. 3 shows the second (upper) tensioning means in a perspective view.

[0096] FIG. 4 and FIG. 5 show the baler of FIG. 1 in the baling forming phase while a bale increases in the bale forming chamber;

[0097] FIG. 6 shows the baler of FIG. 1 in the beginning of the bale ejecting phase wherein the bale is entirely created and wrapped but the tailgate is still in the bale forming position;

[0098] FIG. 7 and FIG. 8 show the baler of FIG. 6 while the tailgate is pivoted from the bale forming position into the bale ejecting position;

[0099] FIG. 9 shows the baler of FIG. 6 wherein the tailgate has reached the bale ejecting position and the step of ejecting the bale has started;

[0100] FIG. 10 shows the baler of FIG. 7 wherein the bale has been ejected and the tailgate is still in the bale ejecting position.

DETAILED DESCRIPTION OF EMBODIMENT

[0101] In the embodiment the invention is used in an agricultural vehicle which is moved over ground in a travelling direction TD, e.g. by being pulled by a tractor, a combine harvester, or a field chopper. Or the vehicle comprises an own motor, i.e. is self-propelled.

[0102] A bale forming apparatus being part of this vehicle [0103] picks up loose crop material (hay, straw, grass, silage, e.g.) from the ground, [0104] conveys this crop material in a direction opposite to the travelling direction TD towards a bale forming chamber, [0105] injects the crop material into the bale forming chamber, [0106] and forms under pressure a round-cylindrical bale in the bale forming chamber.

[0107] This round-cylindrical bale has two parallel circular front faces and a cylindrical circumferential surface extending between these two front faces. The bale forming apparatus wraps this formed bale in the bale forming chamber into wrapping material (strands of twine, a net, or a plastic foil, e.g.), opens a tailgate, ejects the bale out of the bale forming chamber, and deposits the wrapped bale onto the ground.

[0108] The bale forming chamber is partially surrounded by an endless pressing means, e.g. by several parallel pressing belts or pressing chains. The diameter of the drum-shaped bale forming chamber increases while and as the bale is increasing, i.e. the bale forming chamber has a variable size.

[0109] FIG. 1 shows in a side view the bale forming apparatus of the embodiment in a state before the creation of a round bale has started. The bale forming chamber is therefore empty. The baler is propelled in the traveling direction TD (in FIG. 1 from right to left). The following baler parts are shown in FIG. 1: [0110] a towing unit 1 for coupling the non-propelled round baler with a pulling vehicle, [0111] a left wheel 2 and a corresponding right wheel (not shown), [0112] a pick-up unit 3 with several spring-mounted tines 4.1, 4.2, [0113] a pivotal downholder 30 arranged angularly above the pick-up unit 3, [0114] a casing with a front housing (fixed casing part) 5 and a tailgate (moveable casing part) 6, [0115] two driven starter rollers 21.1, 21.2 implemented as pressing rollers and forming the borders of the inlet for crop material wherein the inlet guides into the bale forming chamber, [0116] an endless pressing means 7 comprising several parallel pressing belts which partially surround the bale forming chamber, [0117] a lower tensioning member which can be pivoted with respect to the front housing 5 around a lower horizontal pivoting axis 8 being perpendicular to the travelling direction TD, [0118] an upper tensioning member which can be pivoted with respect to the front housing 5 around an upper horizontal pivoting axis 9 being parallel to the lower pivoting axis 8, [0119] an approximately vertical tensioning actuator 10, [0120] several guiding rollers 19.1, 19.2, 19.3 mounted at the front housing 5, [0121] several guiding rollers 20.1, 20.2, 20.3 mounted at the tailgate 6, and [0122] a wrapping apparatus 11 with a rotatably mounted wrapping material reel 12 wherein the wrapping apparatus 11 is mounted at the tailgate 6.

[0123] In FIG. 1 the tailgate 6 is in a bale forming position and is connected with the front housing 5, e.g. by two locking pawls engaging two corresponding pins. The wrapping apparatus 11 is rigidly mounted at the tailgate 6.

[0124] The lower tensioning member serves as the first tensioning member and comprises [0125] a lower first lever member 13, [0126] a lower second lever member 14 with a bifurcation providing two free ends, [0127] a bale pushing element 15 mounted at one free end of the lower second lever member 14, [0128] one lower moveable guiding roller 16.2 mounted at the other free end of the lower second lever member 14, and [0129] a further lower moveable guiding roller 16.1 mounted at the lower second lever member 14 between the lower pivoting axis 8 and the other free end with the roller 16.2.

[0130] The lower first lever member 13 connects the tensioning actuator 10 with the upper first member 14 and does not carry a guiding roller. The two lower lever members 13, 14 are rigidly connected with each other by means of a tube defining the lower pivoting axis 8.

[0131] The upper tensioning member serves as the second tensioning member and comprises [0132] one upper lever member 17 and [0133] one upper moveable guiding roller 18 mounted on the free end of the upper lever member 17.

[0134] The parallel endless pressing belts 7 are guided around several guiding rollers, among them the following rollers: [0135] the lower moveable guiding rollers 16.1, 16.2 of the lower tensioning member, [0136] the upper moveable guiding roller 18 of the upper tensioning member, [0137] the stationary guiding rollers 19.1, 19.2, 19.3 mounted at the front housing 5, and [0138] the stationary guiding rollers 20.1, 20.2, 20.3 mounted at the tailgate 6.

[0139] At least one guiding roller mounted at the front housing 5 is driven and moves the pressing means 8.

[0140] Every lever member 13, 14, 17 comprisesseen in the travelling direction TDa left lever holding arm and a right lever holding arm. At its free end every lever member 13, 14, 17 carries a guiding roller 16.1, 16.2, 18 which can rotate around its own rotational axis with respect to the lever member. This guiding roller is rotatably arranged between the two lever holding arms. Every lever member can be pivoted around a pivoting axis 8, 9 with respect to the front housing 5 and extends rearward from this pivoting axis. This pivoting axis extends perpendicular to the travelling direction TD and to the drawing plane of FIG. 1.

[0141] In place of a guiding roller an alternative guiding element may be used, i.e. a traversal bearing or a rod with a smooth surface with low friction.

[0142] In the embodiment the bale pushing element 15 comprises a traversal rod which is rigidly or rotatably mounted between the two lever holding arms of the lower second lever member 14. It is also possible that one guiding roller further serves as a bale pushing element touching and pushing a bale in the bale forming chamber.

[0143] FIG. 1 shows the upper lever pivoting axis 9 for the upper lever member 17 of the upper tensioning member. The two lower lever members 13, 14 of the lower tensioning member are rigidly connected with each other and are both pivotal around the same lower lever pivoting axis 8. A distance between the two pivoting axes 8, 9 occurs.

[0144] The tensioning actuator 10 is pivotally connected [0145] with the upper lever member 17 in an upper pivoting axis 22.1 and [0146] with the lower first lever member 13 in a lower pivoting axis 22.2.

[0147] The tensioning actuator 10 is biased. The biased tensioning actuator 10 tends to shift the upper pivoting axis 22.1 away from the lower pivoting axis 22.2, i.e. to increase the distance between these two pivoting axes 22.1, 22.2.

[0148] In one implementation a distance sensor (not shown) measures the distance between the two pivoting axes 22.1, 22.2 and thereby the length of the actuator 10. This measured distance is a value indicative of the tension applied by the pressing belts 7 onto the tensioning actuator 10. This tension tends to reduce the length of the tensioning actuator 10.

[0149] FIG. 2 shows five lever arms between the tensioning actuator 10 and three guiding roller 16.1, 16.2, 18. As can be seen in FIG. 1 and FIG. 2 the following two lever arms for the tensioning actuator 10 with respect to the guiding roller 18 on the lever member 17 occur: [0150] LA 1.1 from the lower pivoting axis 8 of the lower tensioning member 13, 14 to the lower pivoting axis 22.2 of the tensioning actuator 10, [0151] LA 1.2 from the upper pivoting axis 9 of the upper tensioning member 17 to the upper pivoting axis 22.1 of the tensioning actuator 10.

[0152] The following three lever arms for guiding rollers occur: [0153] LA 2.1 from the lower pivoting axis 8 of the lower tensioning member to the rotating axis of the lower moveable guiding roller 16.1, [0154] LA 2.2 from the lower pivoting axis 8 to the rotating axis of the lower moveable guiding roller 16.2, and [0155] LA 2.3 from the upper pivoting axis 9 of the upper tensioning member 17 to the rotating axis 27 of the upper moveable guiding roller 18.

[0156] In the embodiment the length of the lever arm LA 1.2 at the upper lever member 17 for the tensioning actuator 10 is much smaller than the length of the lever arm LA 2.3 at the upper lever member 17 for the upper moveable guiding roller 18, preferably less than 25% of LA 2.3, cf. FIG. 2. The effect achieved by this implementation is described below.

[0157] The length of the lever arm LA 1.1 at the lower lever member 14 for the tensioning actuator 10 is also smaller than the length of the lever arm LA 2.1 for the lower moveable guiding roller 16.1 but has at least half the length of LA 2.1. The lever arm LA 2.2 is larger than the lever arm LA 2.1.

[0158] FIG. 3 shows in a perspective view the upper tensioning member 17 and an upper part of the tensioning actuator 10. The pressing belts and the casing are not shown for sake of clarity.

[0159] FIG. 3 shows the following parts: [0160] the tensioning actuator 10, [0161] the upper moveable guiding roller 18 which can rotate around the rotating axis 27, [0162] the left lever holding arm 17.1 and the right lever holding arm 17.r of the upper lever member 17 which can rotate synchronously around the axis 9, [0163] a hollow axle 26 rigidly connected with the lever holding arms 17.1, 17.r, [0164] two connecting rods 25.1, 25.r rigidly connected with the axle 26 and pivotally connected with the tensioning actuator 10 in the pivoting axis 22.1, and [0165] two stationary guiding rollers 19.1, 19.2 mounted at the front housing 5.

[0166] The terms left and right refer to the travelling direction TD.

[0167] FIG. 3 shows a left tensioning actuator member 10.1 pivotally connected with the left connecting rod 25.1. The right tensioning actuator member is not shown in FIG. 3 and is pivotally connected with the right connecting rod 25.r. In the following the term tensioning actuator 10 denotes the arrangement with the left tensioning actuator member 10.1 and the right tensioning actuator member.

[0168] In the embodiment the tensioning actuator 10 comprises a left piston-cylinder device 10.1 (part of the left tensioning actuator member) containing a left piston, a right piston-cylinder device (part of the right tensioning actuator member) containing a right piston, a closed loop for fluid, and a relief valve. The piston head of the piston in a hydraulic cylinder delimits an upper cylinder chamber (piston rod side) and a lower cylinder chamber (base side) both filled with a fluid. In the embodiment the pressing means 7 tends to press the piston into the cylinder, thereby shortening the left tensioning piston-cylinder device 10.1. If the pressure from above onto the piston exceeds a given threshold, the valve is opened, fluid can flow from the lower chamber through the relief valve into the upper chamber, and the length of the tensioning actuator 10 is reduced. In a further implementation the pressing belts 7 tend to pull the pistons of the tensioning actuator 10 out of the respective cylinder.

[0169] It is also possible to use helical springs in place of hydraulic cylinders. These springs tend to expand and can be compressed against the spring force. Thanks to the invention the tensioning actuator 10 needs not to be switched or adjusted during operation, in particular not at the end of the bale forming phase. As mentioned above the length of the tensioning actuator 10 is measured. The measured length is used for deriving the bale diameter.

[0170] The left piston-cylinder device 10.1 of the tensioning actuator 10 is connected with the left connecting rod 25.1 and the right piston-cylinder device with the right connecting rod 25.r. The tensioning actuator 10 can pivot with respect to the two connecting rods 25.1, 25.r and thereby to the upper tensioning member around the upper pivoting axis 22.1. The lever member 17 can pivot with respect to the front housing 5 around the upper pivoting axis 9.

[0171] In the situation shown in FIG. 1 the bale forming chamber is empty. The tensioning actuator 10 is fully expanded, i.e. the distance between the pivoting axes 22.1 and 22.2 is maximal.

[0172] Loose crop material is picked up from the ground and is injected through the inlet between the starter rollers 21.1, 21.2 into the bale forming chamber. This bale forming chamber is surrounded by the pressing belts 7 and the starter rollers 21.1, 21.2. The pressing belts 7 are driven by at least one driven guiding roller (in FIG. 1 driven anti-clockwise) and form under pressure an increasing bale B.

[0173] In the embodiment the guiding rollers 16.1, 16.2, 18 of the tensioning members are the only moveable guiding rollers for the pressing belts 7. Moveable means: the rollers can be shifted in a direction perpendicular to their own respective rotating axes. Therefore the pressing belts 7 tensioned by the increasing bale B can only move laterally these three guiding rollers 16.1, 16.2, 18. The other guiding rollers are stationary, e.g. can only rotate around their own rotating axes. The step of moving these moveable guiding rollers 16.1, 16.2, 18 changes the positions of the pistons in the cylinders of the tensioning actuator 10. Therefore these piston positions are a measure for the bale diameter. In one implementation these piston positions are measured during the bale forming phase and serve as a value indicative of the bale diameter. It is also possible to measure the length of the tensioning actuator 10 as described above.

[0174] FIG. 4 and FIG. 5 show two different situations during the bale forming phase. In FIG. 4 the bale B has not yet reached a required final size (diameter). In FIG. 5 the bale B has reached the required size and the wrapping procedure starts. During the wrapping procedure the bale B in the bale forming chamber is wrapped into wrapping material (into a net or a plastic film or strands of twine, e.g.). A web of wrapping material is pulled from the supply reel 12 and is injected into the bale forming chamber. The bale forming phase is finished when the required numbers of wrapping material layers are placed around the bale B in the bale forming chamber. Afterwards the web of wrapping material is severed.

[0175] As can be seen in FIG. 4 and FIG. 5, the increasing bale B applies a tensioning force onto the pressing means 7. Those segments of the pressing belts 7 which surround the bale forming chamber are made longer and the further segments of the pressing belts 7 are made shorter. Therefore the pressing means 7 pulls at the moveable guiding rollers 16.1, 16.2, 16.3, 18. This has at least one of the following effects: [0176] The upper tensioning member with the upper moveable guiding roller 18 is pivoted downwards. [0177] The lower tensioning member with the lower moveable guiding rollers 16.1, 16.2, 16.3 is pivoted upwards.

[0178] As the two tensioning members are pivoted against each other, the distance between the two pivoting axes 22.1, 22.2 of the tensioning actuator 10 is reduced. This distance reduction is enforced against the retaining force of the tensioning actuator 10. The pistons of the tensioning actuator 10 are pressed into the hydraulic cylinders. Or the springs of the tensioning actuator 10 are compressed. In both implementations the length of the tensioning actuator 10 is reduced.

[0179] The diameter of the increasing bale B in the bale forming chamber is measured and compared with a given threshold (the required final diameter). In the embodiment the diameter is derived from the following two measured values: [0180] the distance between the two pivoting axes 22.1 and 22.2 of the tensioning actuator 10, i.e. the length of the tensioning actuator 10, and [0181] the pivoting angle of the lower tensioning member around the pivoting axis 8 with respect to the front housing 5.

[0182] The tensioning actuator 10 continuous to press against both tensioning members against the tensioning force of the pressing means 7 until the bale reaches its final diameter and is wrapped and no further crop material is injected into the bale forming chamber. This keeps the pressing means 7 being guided by the guiding rollers 16.1, 16.2, 18.

[0183] The lever arm LA 1.2 between the upper pivoting axis 8 of the upper tensioning member and the upper pivoting axis 22.1 of the tensioning actuator 10 is much shorter than the lever arm LA 2.3, cf. FIG. 2. Therefore the pressing means 7 pivots downwards the upper tensioning member against the force of the tensioning actuator 10 into an approximately horizontal position as shown in FIG. 4 to FIG. 6. The tensioning actuator 10 presses from above against the lower tensioning member and forces the lower tensioning member downwards. The moveable guiding rollers 16.1, 16.2, 18 are pressed against the pressing means 7 and keep it tensioned. The tailgate 6 remains in the bale forming position during the entire bale forming phase.

[0184] In the situation shown in FIG. 6 the bale in the bale forming chamber is entirely wrapped into wrapping material. The tailgate 6 is still in the bale forming position. The tensioned pressing belt 7 applies a pivoting force onto the upper tensioning member which pivots the upper tensioning member. Therefore the bale pushing element 15 on the lower second lever member 14 touches the circumferential surface of the bale B from angularly above.

[0185] In the situation shown in FIG. 6 the mechanical connection between the front housing 5 and the tailgate 6 has been released. The tailgate 6 starts its pivotal movement away from the front housing 5 from the bale forming position into the bale ejecting position. In the embodiment two vertical hydraulic piston-cylinders devices (not shown) are expanded and pivot the tailgate 6 upwards and away from the front housing 5.

[0186] FIG. 7 and FIG. 8 show two intermediate situations during the pivotal movement of the tailgate 6 from the bale forming position into the bale ejecting position. The tailgate 6 has not yet reached the bale ejecting position (the fully opened position). In FIG. 9 the tailgate 6 has reached the bale ejecting position. An aperture for ejecting the bale B is provided.

[0187] The tensioning actuator 10 remains pretensioned (biased) and tends to pivot the upper tensioning member 17, 18 away from the lower tensioning member throughout the entire bale ejecting phase. A comparison of FIG. 4 to FIG. 6 with FIG. 7 to FIG. 9 shows that in FIG. 7 to FIG. 9 the upper tensioning member 17, 18 is pivoted upwards and away from the bale B. The pivotal movement of the upper tensioning member 17, 18 is effected by the biased tensioning actuator 10. As the tailgate 6 is no longer in the bale forming position, the tensioning force which the pressing means 7 applies onto the upper guiding roller 18 and therefore onto the upper tensioning member 17, 18 decreases. Despite of the short lever arm LA 1.2 and of the long lever arm LA 2.3 the tensioning actuator 10 can now surpass the tensioning force of the pressing means 7 and can pivot upwards the upper tensioning member 17, 18. The upper tensioning member 17, 18 can reach an approximately vertical position, cf. FIG. 8.

[0188] Without this pivotal movement caused by the tensioning actuator 10 the pressing means 7 may lose its contact with a guiding roller and may hang in a loose position into the bale forming chamber. If the tailgate 7 is later moved back into the bale forming position for creating a new bale, the pressing means 7 would perhaps not be guided properly or not be driven properly by a guiding roller. The invention avoids this undesired situation as the tensioning actuator 10 pivots the upper tensioning member 17, 18 away from the lower tensioning member. This effect is achieved without changing an operating parameter of the tensioning actuator 10.

[0189] The tensioning actuator 10 continues to apply a force onto the two tensioning members. Due to the short lever arm LA 1.2 the upper pivoting axis 22.1 of the tensioning actuator 10 can only be moved upwards along a small distance. Therefore the tensioning actuator 10 pivots the lower pivoting axis 22.2 and therefore the lower tensioning member downwards. This effect, the tensioning force of the pressing belts 7, and the force of gravity pivot the lower tensioning member against the bale B. The connected bale pushing member 15 applies a pushing force from angularly above onto the circumferential surface of the wrapped bale B. The tensioning actuator 10 operates like a spring if the bale B applies a counter-acting force back onto the bale pushing element 15. The pivoted bale pushing member 15 and the spring-like effect help to eject the bale B quickly out of the bale forming chamber. The bale pushing element 15 hits the bale B. Additionally the pressing means 7 helps to eject the bale B.

[0190] In the embodiment the tensioning actuator 10 is connected with the upper tensioning member via the connecting rods 25.1, 25.r, see FIG. 3. Therefore the tensioning actuator 10 can pivot the upper tensioning member anti-clockwise into an approximately vertical position (FIG. 8) and further away from the tailgate 6 (FIG. 9, FIG. 10). This effect further tensions the pressing means 7 and avoids the undesired situation that the pressing means loses contact to the guiding rollers.

[0191] FIG. 10 shows a situation in which the bale B is entirely ejected out of the bale forming chamber and is deposited onto the ground. It is possible that a tilting unit tilts the wrapped bale B onto a front face. The tailgate 6 is on its way back into the bale forming position. As no bale is in the bale forming chamber, the force of gravity pivots the lower tensioning member downwards. The force of gravity, the tensioning actuator 10 being fully expanded, and the pressing means 7 pivot the upper tensioning member downwards. The situation of FIG. 1 occurs again. A further bale can be formed in the bale forming chamber.

[0192] Reference signs used in the claims will do not limit the scope of the claimed invention. The term comprises does not exclude other elements or steps. The articles a, an, and one do not exclude a plurality of elements. Features specified in several depending claims may be combined in an advantageous manner.

LIST OF REFERENCE SIGNS

[0193]

TABLE-US-00001 B round bale TD travelling direction 1 towing unit for coupling the baler with pulling vehicle 2 left wheel 3 pick-up unit 4.1, spring-mounted tines of the pick-up unit 3 4.2 5 front housing (fixed casing part) 6 pivotal tailgate (moveable casing part) 7 pressing means comprising several parallel pressing belts, partially surrounds the bale forming chamber 8 lower pivoting axis around which the lower tensioning member can be pivoted with respect to the front housing 5 9 upper pivoting axis around which the upper tensioning member can be pivoted with respect to the front housing 5 10 tensioning actuator, connected with the lower first member 13 and the upper lever member 17 11 wrapping apparatus, mounted at the tailgate 6 12 wrapping material reel of the wrapping apparatus 11 13 lower first lever member of the lower tensioning member, connected with the tensioning actuator 10 14 lower second lever member of the lower tensioning member 15 bale pushing element, mounted at the lower second lever member 14 16.1, lower moveable guiding rollers, mounted at the lower second 16.2 lever member 14 17 upper lever member, connected with the tensioning actuator 10 17.l left lever holding arm of the upper lever member 17 17.r right lever holding arm of the upper lever member 17 18 upper moveable guiding roller, mounted at the upper lever member 17 19.1, stationary guiding rollers mounted at the front housing 5 19.2, 19.3 20.1, stationary guiding rollers mounted at the tailgate 6 20.2, 20.3 21.1, starter rollers, form the borders of the crop material inlet 21.2 22.1 upper pivoting axis of the tensioning actuator 10 22.2 lower pivoting axis of the tensioning actuator 10 25.l left connecting rod between upper lever member and tensioning actuator 10 25.r right connecting rod between upper lever member 17 and tensioning actuator 10 26 traversal axle, rigidly connected with the lever holding arms 17.l, 17.r 27 rotating axis of the upper guiding roller 18 30 downholder B bale created and wrapped in the bale forming chamber LA 1.1 lever arm lower pivoting axis 1 - lower pivoting axis 22.2 LA 1.2 lever arm upper pivoting axis 9 - upper pivoting axis 22.1 LA 2.1 lever arm lower pivoting axis 8 - rotating axis of guiding roller 16.1 LA 2.2 lever arm lower pivoting axis 8 - rotating axis of guiding roller 16.2 LA 2.3 lever arm upper pivoting axis 9 - rotating axis of guiding roller 18 TD travelling direction