GB2091073A - Coulter actuation - Google Patents

Abstract

A seed drill having coulter actuation means comprising a beam (16) connected to the coulters (12), two pressure-operated hydraulic devices (21) that are connected to the beam so as to operate the coulters via the beam and that are connected in parallel in a hydraulic actuation circuit, and adjustable pressure-relief means (42) connected in the actuation circuit to limit the pressure on the supply side of the hydraulic devices to a preselected value corresponding to a required depth of penetration of the coulters when lowering them into work. The adjustable pressure-relief valve (42) is connected in parallel with the hydraulic devices (21) across hydraulic supply and return lines of the actuation circuit, further pressure-relief means (69) may be connected in the return line so as to maintain a predetermined minimum pressure in the return side of said devices (21). A one-way valve (68) may be connected across said further pressure-relief means (69) to allow a flow of fluid to said devices (21) to raise the coulters from work. <IMAGE>

Description

SPECIFICATION Seed drills This invention relates to seed or seed and fertiliser drills.

Seed drills have already been proposed comprising a frame, a series of coulters mounted on the frame at positions which are spaced apart in a direction transverse to the direction of operative forward motion of the drill, together with actuating means capable of thrusting the coulters downwards into the ground to open furrows into which seeds can be dropped.

Such a drill has already been proposed in British Patent No. 1163731, having a beam mounted in a fixed position on the frame, the mounting permitting angular movement of the beam about its longitudinal axis, and a hydraulic ram being coupled to a lever arm on the beam so as to hold the beam, during each pass in a field, in a predetermined position with respect to angular movement about said axis, and thereby to cause a downward thrust to be transmitted to the coulters through resilient thrust transmitting means connected between the beam and the coulters. Said predetermined position of the beam, which determines the depths of penetration of the coulters, can be varied by an adjustable connection between the ram and the frame.

It has also already been proposed in British Patent Application No. 19884/77 to provide such a drill having a beam mounted on the frame between a pair of upright hydraulic rams that are connected to the beam at their upper ends via articulated joint means so that the beams can be raised and lowered by the rams to raise and lower the coulters and can tilt from side to side if the ground profile varies across the drill. While the coulters are lowered into work, the two rams are connected in parallel and are connected through a spool valve to a hydraulic supply so that the rams can be raised and lowered together under the control of the spool valve and can move in opposite directions to one another with the displacement of hydraulic fluid from one ram to the other.

The depth of penetration of the coulters in the soil can be controlled by the pressure supplied to the rams but this is difficult using a simple spool valve. It is preferred therefore to employ removable stops that limit the downwards movements of the ram, but the beam is then held rigidly against tilting movements and does not accommodate transverse variations in ground profile. This is a particular disadvantags with wider drills because they are more likely to meet ground profile variations and yet the beam needs to be longer and will therefore tend to flex more. Such a situation is especially intolerable when the drill is used for direct-drilling work in which seed is sown into un-tilled ground and a Iargethrustforce is applied through the beam to the coulters.

An object of the present invention is to provide a drill having coulter actuations means comprising a beam connected to the coulters and operated by hydraulic devices that control the depth of penetration of the coulters in a readily adjustable member whilst allowing the beam to tilt end to end.

This object is achieved according to the present invention by connecting the pressure-operated hydraulic devices in parallel and providing adjustable pressure-relief means to limit the pressure on the supply side of the said devices to a pre-selected value corresponding to a required depth of penetration of the coulters. The operating pressure and corresponding depth of penetration is therefore automatically controlled at said pre-selected value by the pressure relief means without preventing the trans feroffluid between said devices that accompanies tilting of the beam. The drill operator has therefore to do nothing more that select the value of the operating pressure which will generally remain unchanged during the whole of the subsequent sowing operation.

The return side of said pressure-operated hydraulic devices may be connected directly to a reservoir so that the weight of the coulters acts with the supply pressure in said devices to force the coulters into the ground. However, in a situation where the ground is of low resistance to penetration, it may be desirable to counteract The weight of the coulters.

Preferably, this is done by providing further pressure relief means in the return line so as to maintain a predetermined minimum pressure in the return side of said devices corresponding to the weight of the coulters, so that a pre-selected low pressure setting in the first mentioned pressure-relief means will serve exclusively to achieve the required degree of penetration.

The supply side and return side of said pressureoperated hydraulic devices are so named above when said devices are operating to force the coulters into work. However, it will be appreciated that the connection of these lines to a pressure source and reservoir can be reversed so that said devices act to lift the coulters out of work. In this case, a one-way valve is connected across said further pressure-relief means to allow the reverse fluid flow to said devices.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view from the front and to one side of a combined seed and fertilizer drill according to the invention, the drill being shown in its transport position, Figure 2 is a side elevation view of the drill of figure 1, the drill being shown in its working position, Figure 3 is a cross-section through the spherical bearing connection between the beam and lever arm of the coulter actuation mechanism, Figure 4 is an axial section through the spherical bearing connection of figure 3, Figure 5 is a diagram of the hydraulic control circuit including the rams of the coulter actuation mechanism, and Figure 6 is a section through the adjustable pressure The drawing(s) originally filed was/were informal and the print here reproduced is taken from a later filed formal copy.

relief valve of the coulter actuation mechanism.

The illustrated drill comprises a frame 1, the frame being generally rectangular and formed as a welded structure from U-section folded steel stock. The frame comprises front and rear beams 2, 3 respectively, left and right side beams 4, 5 and two intermediate front to rear stiffening beams 6, 7.

Two ground engageable wheels 8 support the frame, the wheels being mounted one at each side of the frame with their axis of rotation 9 in line with the rear beam 3 of the frame.

A drawbar 10 is mounted on the front beam 2 of the frame for connection to the drawhook or drawbar of a tractor. The drawbar can be pivoted upwards to a transport position in which it is secured by a chain (not shown).

A series of triple disc coulters 12 for opening furrows in the soil are mounted on frame 1 at positions which are spaced apart in a direction transverse to the direction Dofoperativeforward motion of the drill. Each coulter is connected via upper and lower parallel links 14, 15 to the front beam 2 so that it trails behind the beam and maintains a substantially constant attitude relative to the fame 1 as it is raised and lowered. The coulters 12 are arranged in two rows across the width of the drill with the coulters of the front row alternating with those of the back row.

The coulters are operated by an actuation mechanism comprising a transverse overhead beam 16 of square box section that is connected to each of the coulters via a resilient thrust transmitting device 17 so that downwards movement of the beam transfers a thrust to the coulters that cause them to penetrate the ground. Furthermore, the beam 16 is free to rotate about its longitudinal axis and the devices 17 are divided into two sets that lie in front of and behind the beam. The front set are connected to the beam via forwardly projecting arms 18 and are connected to the forward row of coulters, and the rear set are connected to the beam via rearwardly projecting arms 19 and are connected to the rear row of coulters.The two sets of coulters therefore exert opposing angular forces on the beam, whereby changes in loading of the coulters can be distributed between them by angular movement ofthe beam about its longitudinal axis.

The coulters 12 and their mounting arrangement, and the resilientthrusttransmitting devices 17 and their connections to the coulters and beam 16 may all be exactly as described in British Patent Application No. 19884/77 and reference should be made to this application for a more detailed description.

The coulter actuation mechanism further comprises thrust applying means to act on the beam 16 comprising two forwardly/rearwardly extending levers 20 that rotatably support the beam between them at their rear ends, and two double-acting hydraulic rams 21 that operate on the front ends of the levers 20. The levers 2û are supported so as to pivot about a common axis parallel to the axis of the beam 18. Each lever 20 is pivotallysupported in its central region on an upright support 22 carried on an intermediate beam 6 or 7 at its lower end.The rams 24 are connected between said front ends of the levers 20 and the front beam 2 so that extension of the rams causes the levers to force the overhead beam 16 downwards.

The levers 20 are each located at an intermediate point between the adjacent free end of the beam 16 and the centre of the beam 50 as to help support the beam uniformly throughout its length and thereby reduce any tendency for the beam to bend when the thrust forces are applied through it. In the illustrated drill, each lever is located about a quarter of the length of the beam from each end and is aligned vertically with one of the intermediate beams 6,7 of the frame so that it can be pivotally supported thereon.

In alternative embodiments of the invention three or more levers 20 can be provided at spaced apart points along the length of the beam. For example, two outer levers could be provided nearer the ends of the beam than in the illustrated embodiment, and a third lever could be provided near the centre ofthe beam. In all embodiments the pivots 25 of the levers would lie on a common axis parallel to the beam and an individual ram would be provided to operate each, the rams all being connected in parallel.

Each support member 22 is carried on top of an intermediate beam 6,7 and is additionally supported laterally by a triangular web 23 on each side that braces the support member and intermediate beam against the front beam 2. The support member has a forked upper end 24 in which the lever 20 is pivotally connected by a pin 25.

The cylinder 26 of each ram 21 is pivotally connected at its lower end to the front beam 2 between a pair of flanges 27 that project from the front of the beam. The piston rod 28 ofthe ram has a forked upper end 29 in which the lever 20 is pivotally connected by a pin 30.

The connection between each lever 20 and the overhead beam 16 comprises a spherical bearing as installed in Figures 3 and 4. The end of the lever 20 carries an outer bearing 31 that supports within it an inner bearing ring 32 connectedto the beam 16, the inter-engaging surfaces of the two rings 31,32 lying on a sphere so that they can rotate relative to one another about the axis of the beam 16, and the inner ring 31 can rotate within the outer ring 32 about an axis perpendicular to said longitudinal axis ofthe beam 16. Rotation about the longitudinal axis of the beam allows angular movement of the beam to distribute coulter loading more evenly as described above.Rotation about axes perpendicular to the longitudinal axis ofthe beam allows tilting of the beam, as illustrated in broken outline in Figure 4, such tilting movement occurring to accommodate variations in ground profile across the width of the drill when the coulters are in work. This tilting movement and the corresponding operation of the rams 21 is described hereinafter.

The inner ring 32 is inserted into the outer ring 31 through the diametrically opposed cut-outs 33 in the inner surface of the outer ring, the inner ring 32 being inserted when orientated at right angles to the outer ring and then being rotated through a right angle. The inner ring 32 is a slide fit on the beam 16 and is eyed te it by v Ou r notches 34 that engage the corners of the beam. A radially projecting lug 35 is provided on the beam adjacent the bearing 31,32. A grease nipple 36 allows the spherical bearing surfaces to be lubricated.

The two rams 21 are connected in parallel to fluid supply lines 37,38 that are connectable to a tractor's hydraulic system including a spool valve 39 (Figure 5) which controls connection of a pressure source 40 and reservoir 41 to the lines 37,38. The spool valve 39 can be operated to connect the pressure source 40 to line 37 so as to extend the rams and thrust the coulters into work, or can be operated to connect the pressure source 40 to line 38 so as to retract the rams and lift the coulters out of work. In both cases, the other line 38 or 37 is connected through the spool valve 39 to the reservoirs 41 so as to form a return flow path. The spool valve 39 also has a neutral position in which the lines 37 and 38 are closed by the valve to isolate the rams from the pressure source 40 and reservoir 41.In this neutral condition, fluid can still flow between the two rams if a greater reaction force is exerted by the levers 20 on one ram as compared with the other, for example, when the ground profile varies across the width ofthe drill. Fluid is then forced through the parallel interconnections of the rams from the bottom of one ram to the bottorn of the other ram and from the top of said other ram to the top of said one ram. The rams thus change in length relative to one another, the levers 20 change their relative angular orientations, and the overhead beam 16 tilts to accommodate the variation in the ground profile, thereby balancing up the reaction forces applied to the beam 16 and levers 20.

The depth of penetration of the coulters into the soil is dependent upon the thrust force exerted by the rams 21 on the beam 16. This thrust force is controlled so as to control the depth of penetration by providing an adjustable pressure relief valve 42 in the ram circuit across the lines 37 and 38 so that the pressure in line 37 is limited to a maximum value pre-selected by adjustment of the valve relief or vent pressure. Once this pressure is exceeded the valve 42 opens to vent fluid to the return line 38.

The pressure relief valve 42 is of robust construction and for convenience of use by the drill operator is mounted on the front of the front beam 2. Figure 6 illustrates the internal construction of the pressure relief valve. The valve body 43 has a cylindrical bore 44 that contains a spring-loaded ball valve assembly 45 at one end and an adjustable valve seat assembly 46 at its other end so that a ball 47 of the ball valve assembly 45 is urged by a coil spring 48 into engagement with an orifice 49 in the valve seat assembly 46 through which fluid is vented when excess pressure unseatsthe ball 47 against the pressure of the spring 48.

The valve seat assembly comprises a tubular member 50 with said orifice 49 formed axially through it at its inner end. This inner end is sealed by O-rings 51 within the bore 44 so that fluid can only flow through the orifice 49 from a transverse inlet port 52 at one end of the bore 44 to a transverse outlet port 53 at the other end of the bore. Fluid flows through the inlet port 52 into an annular chamber 54 around the member 50 and through a bore 55 in the member 50 into its central cavity 56 and the orifice 49.A collar 57 closes the valve seat end of the bore 44 and rotatably supports a spindle 58 that is a screw fit at its inner end in the cavity 56 of the tubular member 50 so that rotation of the spindle via a hand-wheel 59 controls the position of the member 50 within the bore 44, thereby controlling the loading of the coil spring 48 and thus the relief or vent pressure ofthe valve. A peg 60 projects from the outer wall of the tubular member 50 and engages a longitudinal slot 61 in the bore 44 to key the member 50 against rotation.

A further transverse port 62 is an outlet port that communicates with the inlet port 52 under all conditions and is used to facilitate connection of the rams to the inlet side of the pressure relief valve 42.

The ball valve assembly comprises the ball 47 and a carrier 63 having an annular portion 64 that is a close sliding fit within the bore 44 and a tapered nose portion 65 that carries the ball 47 at its free end.

The shape of this tapered nose portion 65 is such as to smooth the flow of fluid from the orifice 49 to the outlet port 53. Small holes 66 extend through the carrier 63 to allow the flow of fluid from one side to the other, thereby clamping motion of the carrier to avoid valve flutter. The coil spring 48 is located within the annular portion 64 ofthe carrier 62 and engages recesses 67 at either end in the carrier and valve body 43.

As illustrated in Figure 5 the hydraulic circuit includes optional circuitry comprising a check valve 68 and a pressure relief valve 69 to retain a minimum pressure in the upper half of the rams 21 as they are extended to lower the overhead beam 16. Assuming that the stop valve 70 has been closed, fluid flows through the check valve 68 to raise the beam 16.

Consequently, as the beam is lowered into work, fluid flows through the pressure relief valve 69 to the reservoir 41 but this flow ceases if the pressure in the upper half ofthe rams 21 falls below a fixed minimum level set by the pressure relief valve 69.

This retained pressure is such as to counteract the weight of the coulters that is acting to lower the beam 16. This feature is especially advantageous in light soil conditions where the weight of the coulters could otherwise cause excess penetration of the soil.

The stop valve 70 allows this feature to be used at will, the valve being opened to bypass the check valve 68 and pressure relief valve 69, thereby to renderthem ineffectvie.

Other components of the drill such as the altitude control rods 71, the hopper 72, and the seed and fertilizer metering mechanisms 73,74 will not be described in any detail because they may be substantially as described in the aforesaid British Patent Application No: 19884/77. Briefly, however, the altitude control rods 71 serve to orientate the overhead beam 16 in a mean position with the front and rear rows of coulters raised equally for transport.

The hopper 72 is divided internally into a front seed compartment and a rear fertilizer compartment. The metering mechanisms 73,74 measure out seed and fertilizer respectively that is delivered to the coulters through feed tubes 75. The metering mechanisms are driven from the wheels 8 by gear trains housed in housing 76. A clutch (not shown) interrupts the drive to the metering mechanisms when the overhead beam 16 is raised. A control linkage 77 connects the beam 16 to the clutch.

Two retractable parking stands 78 are provided on the frame 1 and a screw jack 79 on the drawbar 10.

Claims (6)

1. A seed drill having coulter actuation means comprising a beam connected to the coulters, pressure-operated hydraulic devices that are connected to the beam so as to operate the coulters via the beam and that are connected in parallel in a hydraulic actuation circuit, and adjustable pressurerelief means connected in the actuation circuit to limit the pressure on the supply side of the hydraulic devices to a pre-selected value corresponding to a required depth of penetration ofthe coulters when lowering them into work.

2. A drill as claimed in claim 1 in which the adjustable pressu re-relief valve is connected in parallel with the hydraulic devices across hydraulic supply and return lines of the actuation circuit.

3. A drill as claimed in claim 2 in which further pressure-relief means is connected in the return line so as to maintain a predetermined minimum pressure in the return side of said devices.

4. Adrill as claimed in claim 3 in which a oneway valve is connected across said further pressure-relief means to allow a flow of fluid to said devices to raise the coulters from work.

5. A drill as claimed in claim 4 in which a by-pass is provided across the one-way valve and further pressure-relief means and is openable and closeable at will.

6. A seed drill substantially as herein described with reference to the accompanying drawings.