MACHINE FOR FORMING CYLINDRICAL BALES OF CROP

Abstract: Baling machines with a variable volume baling chamber usu­ ally produce dense bales of crop which is the normal re­ quirement. It is sometimes desirable, due to wet operating 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 hydraulic tension cylinders against expansion of the chamber as the bale grows in size. In the present invention pressure in the rod ends of these cylinders (80) is controlled by a valve (96) movable be­ tween a position allowing one-way flow from a source of hydraulic pressure to the rod ends and a position allowing free flow. In the one-way position of the valve (96) the ends of the cylinders (80) are connected through a high pressure re­ lief valve (104), whereas in the free flow position this relief valve (104) is by-passed and the ends are connected via a low pressure relief valve (102). The free flow position affords the production of a soft core, and thereafter the valve is moved to the one-way po­ sition to give the bale a dense outer portion.

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 piston and cylinder unit which is arranged so that a first end thereof can provide resistance to increase in the said volume and which is connected to a first line which is connectible to a source of pressurised hydraulic fluid, valve means in the first line allowing one-way flow to the first end of the unit and a first relief valve disposed at the unit side of the valve means between the ends of the unit to open at a predetermined first pressure in the first end of the cylinder unit. Machines, towed by a tractor, for forming large cylindrical 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 which resist their upward movement sufficiently to ensure that a dense bale is formed. 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 piston and cylinder units 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 units. Pressure in the rod ends resists extension of the units 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, of also EP-A-0 130 258 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. According to the present invention the valve means is movable between a position allowing the said one-way flow and a position allowing free flow to and from the first end, a second line connects the source side of the valve means to the second end of the unit, and a second relief valve is disposed in the second line to open at a predetermined second pressure in the first line when the valve means is brought in the free flow position, the first pressure being substantially greater than the second pressure. This arrangement permits the production of a dense bale when the valve means is in the one-way flow position and a bale (or core) of a minimum density when in the free flow position. Preferably the valve means is arranged to be controlled by the driver from his working position in the tractor which tows the machine. In this event the valve means can be solenoid actuated. An embodiment 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; and Fig. 2 is a diagram of a 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 pluralility 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. 2) 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 two way, normally closed, poppet-type, pilot-operated, solenoid actuated, directional control 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 hand lock valve 100 to the piston ends of the gate cylinders 84. The line 94 is connected on the coupler side of the control valve 96 to the line 98 through a low pressure relief valve 102, and on the tension cylinder side of the control valve 96 also to the line 98 through an adjustable high pressure relief valve 104. Control of the solenoid of the valve 96 is exercised through an electrical circuit 106 which is shown in Fig. 1 and in which: the solenoid (i. e. the solenoid winding) of the valve 96; an automatic bale size switch 108 adjacent the tension arm 62 on the baling machine; and a manual control switch 110 on a monitor box 112 in the driver's cab of the tractor are all disposed in series with an electrical source 114 on the tractor. Thus with both the switch 108 and the switch 110 closed the solenoid of the valve 96 will be actuated to move the valve 96 to its full flow position, and if either one or both of the switches is (are) open the circuit to the solenoid is broken and the valve 96 will revert to its one-way flow position. The switch 108 operates in dependence on the position of the tension arm 62 during its swing. In particular, a short trigger arm 116 which is rigid with the transverse shaft 60 and which therefore swings with the tension arm 62 opens the switch 108 from its "home" closed condition when the tension arm 62 has swung to the necessary predetermined angle. The trigger arm 116 and the switch 108 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 110 in the monitor box 112 incorporates a signal light which is on when circuit 106 is made. The operation of the hydraulic circuit will now be described. The control valve 96 is shown with the solenoid not actuated in a (check valve) position allowing one-way flow of fluid from the coupler 90 to the rod ends of the tension cylinders 80, the switch 110 being open. With the valve 96 in this position a dense bale will be formed. The adjustable relief valve 104 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 flow through the valve 96, (and also the piston ends of the gate cylinders 84 thereto if the hand lock valve 100 is in its position in Fig. 2). 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 96 must be actuated to bring the valve into the free flow position, i.e. the operator closes the switch 110 in his monitor 112. The effect of this is to by-pass the relief valve 104, which has the above-mentioned high pressure setting for opening, and for the control of the pressure in the rod ends of the tension cylinders 80 to be taken over by the relief valve 102 which is set to open at a considerably lower pressure, e. g. at only 50 bars. Thus the tension cylinders 80 will resist the movement of the tension arms 62 far less and a soft core will be baled. The low pressure setting of 50 bars for the valve 102 is the value of the pressure difference required between the rod and piston ends of the cylinders 80 in order to be able to retract the rods. At the chosen size of core the tension arm 62 reaches the predetermined angle necessary for the trigger arm 116 to open the bale size switch 108, thus breaking circuit 106 which ceases to actuate the solenoid of the valve 96 causing the valve to revert to its one-way flow position. 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 104 and the density of the outer bale portion being produced is high. Should the driver wish to produce a completely soft bale, the circuit 106 must be maintained as made during the entire operation. He therefore closes the control switch 110 initially as before, but adjusts the relative positions of the trigger arm 116 and the bale size switch 108 so that the arm cannot open the switch 108 throughout the entire swing of the arm.

Claims: A machine for forming cylindrical bales of crop having a variable volume baling chamber (54) and a hydraulic system which includes a piston and cylinder unit (80) which is arranged so that a first end thereof can provide resistance to increase in the said volume and which is connected to a first line (94) which is connectible to a source of pressurised hydraulic fluid, valve means (96) in the first line (94) allowing one-way flow to the first end of the unit (80) and a first relief valve (104) disposed at the unit side of the valve means (96) between the ends of the unit (80) to open at a predetermined first pressure in the first end of the cylinder unit (80) characterised in that the valve means (96) is movable between a position allowing the said one-way flow and a position allowing free flow to and from the first end, a second line connects the source side of the valve means (96) to the second end of the unit (80), and a second relief valve (102) is disposed in the second line to open at a predetermined second pressure in the first line (94) when the valve means (96) is brought in the free flow position, the first pressure being substantially greater than the second pressure. A machine according to claim 1 characterised in that the valve means comprise a solenoid-actuated valve (96). A machine according to claim 2 characterised in that the valve (96) is a poppet-type in its one-way flow position. A machine according to claim 2 or 3 characterised in that the solenoid-actuated valve (96) is in a circuit (106) connectible with a control switch at an operator's position on the tractor. A machine according to claim 4 characterised in that the circuit (106) includes a bale size switch (108) arranged on the machine in series with the control switch (110) to be opened when a growing bale has reached a predetermined size. A machine according to claim 5 characterised in that the machine has an abutment (116) movable with the chamber (54) as it increases in volume, the abutment (116) being disposed to contact the bale size switch (108) at the said predetermined size to open the switch (108). A machine according to claim 6 characterised in that the position of the abutment (116) relative to the bale size switch (108) can be adjusted to vary the said predetermined size of the growing bale at which the abutment (116) opens the switch (108). A machine according to claim 6 or 7 characterised in that the position of the abutment (116) relative to the bale size switch (108) can be adjusted to a position in which the abutment (108) does not contact the bale size switch (108) 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 4 to 8 and the tractor has the said control switch (110) 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