MACHINE FOR FORMING CYLINDRICAL BALES OF CROP

Abstract: Baling machines with a variable volume baling chamber usually produce dense bales of crop which is the normal requirement. It is sometimes desirable, due to wet opera­ ting conditions, for the bale to have a "soft" core which can more easily have its moisture reduced. The density of a bale depends in conventional machines on the resistance offered by the rods of a pair of hydraulic tension cylin­ ders against expansion of the chamber as the bale grows in size. In the present invention the ends of these cylinders (80) are connectible by a valve (100) which at the same time allows only one-way flow from the piston ends of a pair of gate cylinders (84) which would otherwise be connected to the piston ends of the tension cylinders (80). This arrangement avoids unwanted creeping extension of the gate cylinders (84) by fluid trapped in the hydraulic lines.

Description: This invention relates to a machine for forming cylindrical bales of crop having a variable volume baling chamber and a hydraulic system which includes a first piston and cylinder unit having rod and piston ends and being arranged so that it can provide resistance to increase in the said volume, a second piston and cylinder unit having rod and piston ends and being arranged so that it can move a component of the machine between two positions, a source of pressurized hydraulic fluid, a first hydraulic line connectible to the source and being branched with one part containing a check valve to the rod end of the first unit and with another part to the rod end of the second unit, a second hydraulic line connectible to the source and being branched with a first part to the piston end of the first unit and with a second part to the piston end of the second unit, a third hydraulic line containing a pressure relief valve and being connected to the first and second lines downstream of the said check valve, and a fourth hydraulic line connecting the rod end of the first unit to the second line and containing valve means movable between a position stopping flow between the ends of the first unit and a position allowing free flow between the ends of first unit. Machines, towed by a tractor, for forming large cylindrcal bales of hay (so-called "round balers") are well known. As the machine advances, the crop is removed from a windrow by a pick-up mechanism and delivered rearwardly to a baling chamber where it is rolled round upon itself into a bale. In one form of such a machine the baling chamber is defined by runs of belts which move outwardly to enlarge the chamber so as to accommodate the bale as it grows in size. The belts are trained over rolls connected to a drive. A pair of rolls is sited at the top of the chamber and these rolls are carried by a swingable tension arm on either side of the machine enabling the two rolls to swing upwardly as the girth of the bale increases. The tension arms are connected to hydraulic piston and cylinder units, i. e. tension cylinders, which resist their upward movement sufficiently to ensure that a dense bale is formed. Hydraulic piston and cylinder units are used to raise a rear gate of the machine to release a completed bale and these units, i. e. gate cylinders, are connected to the tension cylinders. In most circumstances a uniformly dense bale is highly desirable. However, in some conditions it is useful for the core (or indeed the entire bale) to be of low density or "soft". Such conditions occur, for example, when the crop has to be baled whilst wet, and hot air is subsequently blown through the completed bale to reduce the excess moisture. This treatment is obviously more effective with a looser bale. Certain specialist applications also make a softer bale worthwhile, e. g., a machine for grinding straw prior to its use in mushroom growing beds will more readily accept this type of bale. The hydraulic circuitry involving the tension cylinders which brake the tension arms as referred to above includes fluid lines from quick couplers, connected to the hydraulic supply of the tractor towing the baler, to the rod ends and piston ends respectively of the cylinders. Pressure in the rod ends resists extension of the cylinders and therefore affords the braking effect on the tension arms. Thus, control of this pressure provides control of the density of the bale. In the known "550" round baler, produced and marketed by Deere & Company, the pressure is controlled as follows. A check valve is disposed in the fluid line running from one of the couplers to the rod ends, and allows flow in the direction of the rod ends. The rod and piston ends are connected by a line which runs from a point downstream of the check valve to the piston ends and in which there is an adjustable bale density relief valve. The setting for the opening of this latter valve, typically at 180 bars, determines the pressure at which the rod ends are relieved and hence the density of the bale being formed. It is desirable to be able to minimise the pressure in the rod ends to produce softer bales (or cores) when needed, and yet maintain the capability of the machine to make dense bales. A simple way of achieving this has been proposed in which a valve is disposed between the rod and piston ends of the tension cylinders to open in order to connect the ends for a soft core and to close to enable pressure to be maintained in the rod ends for dense baling. However, the hydraulic circuity connecting the tension cylinders and gate cylinders is such in, for example, the "550" round baler (as will be explained later in detail) that, after closing the gate following release of a completed bale through the raised gate, hydraulic fluid is trapped under pressure in the rod ends of the tension and gate cylinders. This fluid flows to the piston ends to equalize the pressure at the rod and piston ends, but nevertheless due to difference in surface areas at the ends the gate cylinders tend toward unwanted creeping extension and thereby release latches which keep the gate closed with the result that baling cannot start until the latches have again been secured. The present invention enables these difficulties to be reduced or overcome. According to the present invention the valve means are in the second part of the second line and in the fourth line, in the said position stopping flow between the ends of the first unit the valve means allow free flow in the second part of the second line, and in the said position allowing free flow between the ends of the first unit the valve means stop flow in the second part of the second line to the second unit. This arrangement permits the production of a dense bale when the valve means is in the position stopping flow between the ends of the first unit and a bale (or core) of a minimum density when in the free flow position, whilst avoiding or reducing unwanted creeping extension of the second piston and cylinder unit which can be a gate cylinder. Preferably the position stopping flow in the second line to the second unit allows one-way flow from that unit. Embodiments of the invention will now be described with reference to the accompanying diagrammatic drawings in which: Fig. 1 is a view from the left side of a machine for forming large cylindrical bales of hay showing certain details only, and an electrical circuit superimposed thereon; Fig. 2 is a diagram of a hydraulic circuit for the machine in Fig. 1; and Fig. 3 is a diagram of a modified hydraulic circuit for the machine in Fig. 1. In Fig. 1, the baler includes a main frame 10 mounted on a pair of wheels 12. The main frame has an upright fore-and-aft extending wall 14 on either side connected by transverse beams (not shown). A draft tongue 16 is connected to a transverse beam at the front of the frame 10 and extends forwardly for attaching the baler to a tractor (also not shown) which draws the machine. A plurality of lateral rolls extends over the width of the machine. One set of rolls 18, 20, 22, 24, 26, 28 is journalled in the side walls 14, whilst another set consisting of rolls 30, 32, 34 is journalled in a swingable gate 36. There is also a pair of chamber restricting rolls 38, 40 and two belt take-up rolls 42, 44. Six rubber belts 46 are trained side-by-side over the rolls, with the exception of the roll 18 which acts as a stripper roll, to provide the configuration shown and they move in the direction indicated by arrows 48, the stripper roll 18 being driven anti-clockwise as viewed in Fig. 1. However, alternate belts only are trained over the lower foremost roll 22, whilst the remaining belts by-pass this roll, to provide a staggered array which is of no significance in relation to the present invention but which is described in our EP-B-0 070 537. Upwardly extending runs 50, 52 of the belts 46 define a bale-forming chamber 54 the ends of which are provided by the side walls 14 and gate 36 and which has an inlet 56 for crop received from a pick-up 58 beneath it. In order to accommodate the increasing diameter of a growing bale core in the bale-forming chamber 54, the size of the chamber must also increase and a belt take-up and tensioning mechanism is provided at either side of the machine. These mechanisms include: a pair of rearwardly extending tension arms which are mounted rigidly at the forward end of the main frame 10 on a horizontal transverse shaft 60, providing a pivot connection for the arms, and of which the right hand arm 62 only is shown; the belt take-up roll 42 which is supported at either end at an intermediate location on the arms 62; and the pair of chamber restricting rolls 38, 40 supported at the free ends of the arms. The arms are biased in an anti-clockwise direction (in Fig. 1) by a pair of springs, one on either side of the main frame 10, of which only the right hand spring 64 is shown and only its arrangement will be described, the other being similar. The spring 64 is connected at its lower end by a cable 66 which runs over a pulley 68 to a lever portion 70 of the arm 62, the portion 70 being rigid with the pivot shaft 60, and at its upper end by a cable 72 via a pulley 74 to one arm of a bell crank 76 the other arm of which bears one end of the take-up roll 44. The free end of the lever portion 70 is pivotally connected at a point 78 to the piston rod of a piston and cylinder unit 80, loading the arm 62, of which the cylinder is in turn pivotally connected to the frame 10 at a point 82, a similar arrangement being provided also on the left hand side of the machine. A further piston and cylinder unit 84 (on either side of the machine) is connected between pivot points 86, 88 on the gate 36 and main frame 10 for opening and closing the gate. For convenience the units 84 will be referred to as gate cylinders 84, and the units 80 as tension cylinders 80. The arrangement of the relevant hydraulic circuit will now be described. In Fig. 2 quick couplers 90, 92 connect the hydraulic circuit shown to a source of pressurised hydraulic fluid on the tractor. The quick coupler 90 is connected via a line 94 directly to the rod ends of the gate cylinders 84 and, through a check valve 96, to the rod ends of the tension cylinders 80. The quick coupler 92 is connected via a line 98 to the piston ends of the tension cylinders 80 and, by way of a by-pass valve 100 ( in the form of a three-way, two-position, solenoid actuated valve) either to the piston ends of the gate cylinders 84 as shown in Fig. 2 or to the rod ends of the tension cylinders 80. The flow in that part of the line 98 providing connection between the ends of the tension cylinders 80 is restricted to a low value relative to the rest of the hydraulic circuit by sizing the part of the line accordingly or by way of an orifice (not shown) in order to obtain an appropriately substantial pressure drop during closure of the gate 36. In addition, a manual lock valve 102 is disposed in the line between the valve 100 and the gate cylinders 84, and a check valve 104 is arranged parallel to the valve 100 in relation to its connection with the quick couplers 92 and the gate cylinders 84 allowing one-way flow from the latter. The line 94 is connected on the tension cylinder side of the check valve 96 to the line 98 through an adjustable high pressure relief valve 108. Control of the solenoid of the valve 100 is exercised through an electrical circuit 110 which is shown in Fig. 1 and in which: the solenoid (i. e. the solenoid winding) of the valve 100; an automatic bale size switch 112 adjacent the tension arm 62 on the baling machine; and a manual control switch 114 on a monitor box 116 in the driver's cab of the tractor are all disposed in series with an electrical source 118 on the tractor. Thus with both the switch 112 and the switch 114 closed the solenoid of the valve 100 will be actuated to move the valve 100 to its position connecting the rod and piston ends of the tension cylinders 80, and if either one or both of the switches is (are) open the circuit to the solenoid is broken and the valve 100 will revert to its home position shown in Fig. 2 connecting the piston ends of the gate and tension cylinders 80, 84. The switch 112 operates in dependence on the position of the tension arm 62 during its swing. In particular, a short trigger arm 120 which is rigid with the transverse shaft 60 and which therefore swings with the tension arm 62 opens the switch 112 from its "home" closed condition when the tension arm 62 has swung to the necessary predetermined angle. The trigger arm 120 and the switch 112 are relatively adjustable so that this angle can be varied according to the choice of the operator for the core size of the bale. The switch 114 in the monitor box 116 incorporates a signal light which is on when circuit 110 is made. The operation of the hydraulic circuit will now be described. The control valve 100 is shown with the solenoid not actuated in a position allowing flow of fluid between the piston ends of the gate and tension cylinders 84, 80 and the coupler 92, the switch 114 being open. With the valve 100 in this position a dense bale will be formed. The adjustable relief valve 108 is set, for example, at 180 bars at which pressure it will connect the rod and piston ends of the tension cylinders 80 with no return flow through the valve 96. In this manner the tension cylinders 80 offer sufficiently high resistance to the upward swinging movement of the tension arms 62 and thus to the expansion of the bale chamber 54 for a dense bale to be formed. If a soft core bale is required then at the start of baling the solenoid of the valve 100 must be actuated to bring the valve into the position connecting the rod and piston ends of the tension cylinders 80 i. e. the operator closes the switch 114 in his monitor 116. Thus the tension cylinders 80 will not resist the movement of the tension arms 62 and a soft core will be baled. At the chosen size of core the tension arm 62 reaches the predetermined angle necessary for the trigger arm 120 to open the bale size switch 112, thus breaking circuit 110 which ceases to actuate the solenoid of the valve 100 causing the valve to revert to its home position preventing circuit flow between the rod and piston ends of the tension cylinders 80. With the valve in this position, control of the pressure in the rod ends of the tension cylinders 80 is again by way of the high pressure relief valve 108 and the density of the outer bale portion being produced is high. Should the driver wish to produce a completely soft bale, the circuit 110 must be maintained as made during the entire operation. He therefore closes the control switch 114 initially as before, but adjusts the relative positions of the trigger arm 120 and the bale size switch 112 so that the arm cannot open the switch 112 throughout the entire period of formation of the complete bale. The relationship of the positions of the valve 100 to the gate cylinders will now be described. With the valve 100 in its home (non-actuated) position, the connection between the rod and piston ends of the tension cylinders 80 is closed and the piston ends of the tension and gate cylinders 80, 84 are interconnected with the quick coupler 92. Most importantly, when the valve 100 is in its actuated position in which the rod and piston ends of the tension cylinders 80 are connected, flow through the valve 100 to the piston ends of the gate cylinders 84 is stopped although flow from the latter to the quick coupler 92 is still possible through the check valve 104. Such an arrangement overcomes the following problem. If a valve is provided between the ends of the tension cylinders 80 merely to open in order to connect those ends or close to cut the connection, difficulties arise with the gate cylinders 84. When the gate 36 is closed by flow to the rod ends of the gate cylinders 84, after release from the baler of a completed bale, and as a valve controlling this on the tractor is brought to neutral, oil under pressure trapped in the rod side of the cylinders will continue to flow through this valve to the piston sides of the cylinders 80, 84. The pressure will equalize at both ends of these cylinders but this will cause the gate cylinders 84 to tend to extend. The tension cylinders 80 are not affected in the same way, since the tension arms 62 offer sufficient resistance to creeping extension. On the other hand, the only resistance to initial extension of the gate cylinders 84 is provided by very easily opened gate latches. Thus, the gate 36 will tend to be released from these latches and in these circumstances baling will not then be possible. Since, as mentioned above, when the present valve 100 connects the ends of the tension cylinders 80, flow to the piston ends of the gate cylinders 84 is nevertheless stopped, unwanted extension of these cylinders is avoided. It is also possible to close the gate 36 when the valve 100 is in its actuated position because fluid can flow, as also explained above, through the check valve 104 to the tractor from the piston ends of the gate cylinders 84. Internal leakage of the valve 100 should be very low when it is in its home position to maintain pressure for high density baling. Instead of using a single two position by-pass valve 100 as in Figs. 1 and 2, two two-way, two-position, solenoid actuated valves 122, 124, can be employed as shown in Fig. 3. The valve 122 which is normally closed is disposed between the ends of the tension cylinders 80, and the valve 124 which is normally open is between the piston ends of the tension cylinders 80 and the piston ends of the gate cylinders 84. The combined positions of the valves 122, 124 in Fig. 3 correspond to the home position of the valve 100 illustrated in Fig. 2, i. e. the solenoids of the valves 122, 124 are not actuated. Thus the valve 124 is in its free flow position, whilst the valve 122 cuts the connection between the ends of the tension cylinders 80. The valve 122 will be moved on actuation to a free flow position and the valve 124 to a position cutting flow to the piston ends of the gate cylinders 84 corresponding to the actuated position of the valve 100. A check valve incorporated in the valve 124 corresponds to the check valve 104 in Fig.1. Thus the function of the valves 122, 124 taken together is the same as that of the valve 100.

Claims: A machine for forming cylindrical bales of crop having a variable volume baling chamber (54) and a hydraulic system which includes a first piston and cylinder unit (80) having rod and piston ends and being arranged so that it can provide resistance to increase in the said volume, a second piston and cylinder unit (84) having rod and piston ends and being arranged so that it can move a component of the machine between two positions, a source of pressurised hydraulic fluid, a first hydraulic line (94) connectible to the source and being branched with one part containing a check valve (96) to the rod end of the first unit (80) and with another part to the rod end of the second unit (84), a second hydraulic line (98) connectible to the source and being branched with a first part to the piston end of the first unit (80) and with a second part to the piston end of the second unit (84), a third hydraulic line containing a pressure relief valve (108) and being connected to the first and second lines (94, 98) downstream of the said check valve (96), and a fourth hydraulic line connecting the rod end of the first unit (80) to the second line (98) and containing valve means (100, 104 or 122, 124) movable between a position stopping flow between the ends of the first unit (80) and a position allowing free flow between the ends of first unit (80) characterized in that the valve means (100, 104 or 122, 124) are in the second part of the second line (98) and in the fourth line, in the said position stopping flow between the ends of the first unit (80) the valve means (100, 104 or 122, 124) allow free flow in the second part of the second line (98), and in the said position allowing free flow between the ends of the first unit (80) the valve means (100, 104 or 122, 124) stop flow in the second part of the second line (98) to the second unit (84). A machine according to claim 1 characterised in that the position stopping flow in the second part of the second line (98) to the second unit (84) allows one-way flow in the second part of the seond line (98) from the second unit (84). A machine according to claim 2 characterised in that the valve means comprise a solenoid actuated valve or valves (100, 122, 124) for the said stopping of flow and allowing free flow and a check valve (104) for the said one-way flow. A machine according to claim 3 characterised in that the valve means comprise a three-way, two-position, solenoid actuated valve (100) for the said stopping of flow and allowing free flow and a check valve (104). A machine according to claim 3 characterised in that the valve means comprise a two-way, two-position, solenoid actuated, normally closed valve (122) in the fourth line, a two-way, two-position, solenoid actuated, normally open valve (124) in the second part of seond line (98) incorporating the check valve. A machine according to any of claims 3 to 5 characterised in that the solenoid actuated valve (100, 122, 124) or valves is/are in a circuit (110) connectible with a control switch (114) at an operator's position on a tractor. A machine according to claim 6 characterised in that the circuit (110) includes a bale size switch (112) arranged on the machine in series with the control switch (114) to be opened when a growing bale has reached a predetermined size. A machine according to claim 7 characterised in that the machine has an abutment (120) movable with the chamber (54) as it increases in volume, the abutment (120) being disposed to contact the bale size switch (112) at the said predetermined size to open the switch (112). A machine according to claim 8 characterised in that the position of the abutment (120) relative to the bale size switch (112) can be adjusted to vary the said predetermined size of the growing bale at which the abutment (120) opens the switch (112). A machine according to claim 8 or 9 characterised in that the position of the abutment (120) relative to the bale size switch can be adjusted to a position in which the abutment (120) does not contact the bale size switch (112) during the formation of the bale. A machine for forming cylindrical bales of crop in combination with a tractor for towing it characterised in that the machine is a machine according to any of claims 6 to 10 and in which the tractor has the said control switch (114) at the operator's position thereon.

Inventors: ANSTEY, HENRY DENNIS, ROTH, ARSENE, VIAUD, JEAN, Roth, Arsène
Applicants: DEERE & COMPANY
Application year: 1990
Main classification: A01F15
IPC codes: A01F15