Agricultural machine with vibration-damped attachment

Description

[0001] Agricultural Machine with Vibration-Dampened Header The present invention relates to an agricultural machine comprising a carrier vehicle, for example a combine harvester or forage harvester, and a header mounted thereon, typically a cutting unit (see US 2015 / 033692 A1). Such a cutting unit is generally suspended centrally on an infeed of the carrier vehicle and pivotable about an axis oriented in the direction of travel of the carrier vehicle, so that the cutting unit does not have to follow every rolling movement about this axis that the carrier vehicle makes when driving over uneven ground, so that it can maintain an orientation substantially parallel to the ground despite short-term swaying of the carrier vehicle, while at the same time the rolling inclination of the cutting unit can adapt to uneven ground without the carrier vehicle having to make a corresponding rolling movement.To enable such an adjustment of the cutting unit, a swivel drive is provided between the carrier vehicle and the attachment.

[0002] From DE 10 2010 021 133 A1, a working machine is known in which support wheels on both sides of the axle are connected to a frame of the cutting unit via reversibly compliant supports. If one of these support wheels rolls onto a ground elevation and is deflected upwards, the high moment of inertia of the cutting unit means that essentially only the support wheel's support beam yields, and the cutting unit's roll inclination remains unchanged. While this is quite useful for small elevations, a problem arises with larger elevations: if the roll inclination is not adjusted, the cutting unit can collide with the elevation. However, not only the moment of inertia of the cutting unit counteracts an adjustment of the roll inclination, but also the resistance of the support wheel support on the side of the cutting unit facing away from the ground elevation.

[0003] To overcome this disadvantage, the invention proposes that in an agricultural machine comprising a carrier vehicle and a front attachment, the front attachment being pivotably guided on the carrier vehicle about an axis extending in the direction of travel of the carrier vehicle, wherein a support wheel is connected to the front attachment via a damped compressible arm on each side of the axis, a control circuit is provided to decide whether a pivoting movement of the front attachment about the axis is desired or not, and in the case that the pivoting movement is desired, to switch the arm that is compressed by the pivoting movement from a strongly damped compressible state to a substantially undamped state.

[0004] If an arm on one side of the attachment is compressed in contact with a ground elevation, the control circuit can treat the resulting pivoting movement as desirable by switching the opposite arm to a virtually undamped state. This allows the other arm to no longer resist the torque exerted on the attachment by the arm compressed in contact with the ground elevation, thus enabling faster adjustment of the roll angle.

[0005] The support wheels should not bear the weight of the attachment during operation, or at most only to a small extent. Therefore, the torque that an arm can exert on the attachment is normally insufficient to quickly adjust the roll tendency. To achieve this, preferably at least one actuator is provided that acts on both the carrier vehicle and the attachment.

[0006] The control circuit is then expediently configured to treat a pivoting movement of the attachment about the axis, driven by the actuator, as a desired pivoting movement; that is, in a state where the actuator drives a pivoting movement of the attachment about the axis, it switches the arm position to the essentially undamped state, which is compressed by the pivoting movement, thus enabling faster pivoting. The same control circuit can also control the actuator itself.

[0007] By switching the damping from the essentially undamped to the heavily damped state during the downward movement, a rapid pivoting and thus a quick return to near a desired roll angle can initially be achieved; once this has happened, stronger damping can prevent the attachment from contacting the ground or at least slow it down to a harmless speed.

[0008] Different damping values ​​can be achieved in particular by including an actuating cylinder in each arm, and by connecting a chamber of the actuating cylinder to a reservoir via a hydraulic circuit with switchable flow resistance.

[0009] Preferably, the actuator cylinder is a single-acting actuator cylinder.

[0010] The arm can include a link that is articulated at one end to the attachment and defines an axis for the support wheel at the other end. For adjusting the arm, the actuating cylinder can be articulated to both the link and the attachment.

[0011] The hydraulic circuit can include a throttle point and a switching valve parallel to the throttle point; thus, a high damping value can be achieved by closing the switching valve and a low damping value by opening it.

[0012] An open state of the switching valve could, in principle, be used to achieve both a rapid yielding of an arm on one side of the attachment when that side moves downwards, and a rapid extension of the arm during an upward movement. Preferably, however, the hydraulic circuit also includes a check valve parallel to the throttling point to enable rapid extension during an upward movement; this allows the movement behavior of the attachment to be optimized independently for both situations.

[0013] The throttling point can include a pressure regulating valve controlled by the pressure at its port facing the actuator cylinder. This allows for high damping that is independent of the momentary deflection of the attachment during the phases of movement when the switching valve is not actuated.

[0014] Each arm is preferably assigned a ground distance sensor to control the damping as a function of a ground distance measured by the sensor or a difference between ground distances measured by ground distance sensors on either side of the axis. Each ground distance sensor can comprise a wire loop extending downwards from the attachment and deflected or deformed in contact with the ground, the deflection or bending stress of the wire loop being detected to provide a measurement signal representative of the ground distance.

[0015] The switching valve in the hydraulic circuit of one of the arms is preferably configured to open when a first threshold value of the ground distance measured by the ground distance sensor assigned to the arm, or the difference between the ground distance measured by the ground distance sensor assigned to the arm and a ground distance measured by a ground distance sensor on the opposite side of the axis, is exceeded, and to close when a second, lower threshold value of the ground distance or the difference is not reached. Opening during an upward movement has essentially no effect on the damping if, in this case, the hydraulic fluid has a path open via the check valve.

[0016] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. These show: Fig. 1 a schematic front view of an agricultural machine according to the invention; Fig. 2 a schematic side view of a front attachment mounted on a carrier vehicle; Fig. 3 a view of a collapsible arm with a support wheel; and Fig. 4 a diagram of a hydraulic circuit connecting an actuating cylinder to a damped arm and a reservoir.

[0017] Fig. 1 Figure 1 shows a schematic front view of a combine harvester, which serves as a carrier vehicle 1 for a header 2, similar to a harvesting attachment. The width of the header 2 is several times the width of the carrier vehicle 1. The header 2 obscures a lower front section of the carrier vehicle 1, so that essentially only the driver's cab 3 above the header 2 and parts of its front wheels 4 below are visible. The header 2 and the carrier vehicle 1 are connected via an inclined conveyor 5, from which... Fig. 1Only an inlet opening 6 is visible on a rear wall of the attachment unit 2. The attachment unit 2 is pivotable relative to the carrier vehicle 1 about an axis 21 extending in the direction of travel; the axis thus defines a left and a right side L, R of the attachment unit 2, which, as part of a rolling movement about the axis 21, move vertically up and down in opposite phases, but can also spring up and down in the same phase. A reel 8 and a transverse screw conveyor 9 are in Fig. 1 Each is shown with a break in the middle.

[0018] Fig. 2Figure 1 shows in more detail the construction of the attachment 2 and its connection to the carrier vehicle 1. A frame 7 of the inclined conveyor 5 is pivotally connected to the body of the carrier vehicle 1 via a joint 10. The carrier vehicle 1 carries the majority of the weight of the attachment 2 via the inclined conveyor 5. Two actuators 11 extend between body-side attachment points 12 on the body below the joint 10 and attachment-side attachment points 13 located on the rear wall of the attachment 2 adjacent to the lower corners of the inlet opening 6. Thus, by simultaneously actuating both actuators 11 in the same direction, the attachment 2 as a whole can be moved up and down, while extending or retracting either actuator 11 while maintaining the length of the other, or actuating the two actuators 11 in opposite phases, can drive or counteract a rolling movement of the attachment 2.

[0019] Adjacent to the side cheeks 14 at the lateral ends of the attachment 2, damped, collapsible arms 15 are mounted on its underside. As detailed in Fig. 3 As shown, a ground-contacting end of each arm 15 is formed by a support wheel 16; the support wheel 16 is articulated to a fitting 28 via an arm section 17 shown in an approximately horizontal position. The fitting 28 is designed to be mounted on the rear wall of the attachment 2 such that the end of the arm section 17 articulated to the fitting 28 is positioned as shown. Fig. 2 The arm section 17 is shown to be located approximately at ground level with the attachment device 2. The inclination of the arm section 17 is adjustable by an adjusting cylinder 18, which engages the arm section 17 and an upper area of ​​the fitting part 28.

[0020] Each side wall 14 is provided with a ground clearance sensor 19. The ground clearance sensor 19 comprises a wire bracket 20, which is pivotably mounted on the side wall 14 about an axis 29, and a sensor 22 for detecting the rotation angle of the wire bracket 20 about the axis 29, which is representative of the distance between the side wall 14 and the ground.

[0021] As in Fig. 4As shown, a working chamber of the actuating cylinder 18 of one of the arms 15 is connected to a pressure reservoir 23 via a hydraulic circuit. A check valve 24, which blocks flow from the actuating cylinder 18 to the pressure reservoir 23, and a throttling device, here in the form of a pressure regulating valve 25, are connected in parallel in this circuit. An inlet and a control input of the pressure regulating valve 25 face the actuating cylinder 18. Therefore, if the pressure in the cylinder exceeds that of the pressure reservoir by more than a threshold value set on the pressure regulating valve 25, hydraulic fluid flows from the working chamber to the pressure reservoir 23, thereby experiencing a pressure drop in the pressure regulating valve 25. If the attachment 2 has been set into an oscillating motion, the arm 15 can thus dampen and slow down the downward movement of the side of the attachment 2 it supports.

[0022] When this side of the attachment 2 moves upwards again, the arm 15 is relieved of its load, and the pressure in the working chamber of the actuating cylinder 18 is so low that hydraulic fluid flows from the pressure reservoir 23 through the check valve 24 into the working chamber and extends the arm 15. The flow rate through the check valve 24 can be so high that the support wheel 16 of the arm 15 never loses contact with the ground during the upward movement; however, even with a lower flow rate and a possible resulting loss of ground contact during the upward movement, this contact is re-established in an early phase of the subsequent downward movement. If, however, the downward movement is heavily damped from the outset, it can come to a standstill before reaching an equilibrium position, or at least be slowed down so much that, before reaching equilibrium, the attachment is set into oscillation again by driving over an uneven surface.

[0023] Even in the case that a pivoting movement of the attachment device 2 is specifically driven by means of the actuators 11 in order to correct a roll tendency recognized as faulty, strong damping of the arm 15 is disruptive because it delays the achievement of the desired roll tendency.

[0024] To avoid this, a switching valve 26 is provided as a further component of the hydraulic circuit, in parallel to the pressure regulating valve 25 and the check valve 24 between the actuator 18 and the pressure reservoir 23. A control circuit 27 controls the operating state, open or closed, of the switching valve 26 based on measurement data from the ground clearance sensors 19.

[0025] The control of the switching valve 26 assigned to one of the arms 15 can be based solely on measurement data from the ground clearance sensor 19 located on the same side of the attachment 2 as the switching valve 26 itself. If the height measured by the ground clearance sensor 19 exceeds a threshold h1 above an equilibrium height h0, the control circuit 26 opens the switching valve 26. Since hydraulic fluid is already flowing into the working chamber of the actuator 18 via the check valve at the same time, this opening has little effect on the flow resistance that the hydraulic fluid has to overcome. The upward movement is therefore not significantly damped, regardless of the position of the switching valve 26; consequently, upward deflections well beyond the equilibrium position are possible, and the subsequent downward movement also initially remains only marginally damped.

[0026] Only when, during a subsequent downward movement, the height measured by the ground distance sensor 19 falls below a second threshold h2 between h0 and h1, does the control circuit 27 close the switching valve 26. A backflow of hydraulic fluid from the actuating cylinder 18 to the pressure reservoir 23 can now only occur via the pressure regulating valve 25, so that from this point on, further movement is strongly dampened. This ensures that if the downward movement comes to a standstill due to the damping, the height at which this occurs is not far from the equilibrium height h0. Therefore, only a small amount of power from the actuators 11 is required to restore the equilibrium height h0.

[0027] Since the opening state of the switching valve 26 has little influence on the upward movement, the first threshold h1 could also be set equal to h2. However, providing a difference between the two is useful to avoid frequent switching of the valve 26 when the height in the vicinity of h1 and h2 fluctuates slowly and with a small amplitude.

[0028] In the above description, only one side of the attachment 2 and the arm 15 located therein were considered. Since the described control of the switching valve 26 takes place in the same way depending on the height on both sides L and R of the attachment 2, not only can a rolling oscillation of the attachment 2 be dampened, but also an oscillation of the entire attachment 2 in the vertical direction.

[0029] According to a second embodiment, the control circuit 27 evaluates measurement data from ground distance sensors 19 on both sides of the attachment. In this case, it is not necessary to determine an equilibrium height h0 and to set the first and second thresholds h1, h2 at a suitable distance from this equilibrium height h0; it suffices to determine the difference between the heights hL, hR measured to the right and left of the center of the attachment: If this difference exceeds a predetermined amount d1, e.g., corresponding to a roll inclination of the attachment 2 relative to the horizontal of 0.15° or 0.2°, then the control unit 27 opens the switching valve 26 on the respective higher side L or R of the attachment 2, and closes it again when the roll inclination relative to the horizontal has decreased to a lower value d2, e.g., below 0.1°.Thus, the rolling motion of the attachment device 2 is only strongly dampened when it is close to the horizontal, and prolonged periods of the attachment remaining in an inclined position with more than 0.1° of tilt can be prevented.

[0030] Control based on altitude and altitude difference can be combined.

[0031] The control of the switching valve 26 described above, based on measured values ​​from the ground clearance sensors 19, can be linked to the control of the actuators 11: thus, the control circuit 27 can use the measured values ​​from the ground clearance sensors 19 to determine whether the roll tendency of the attachment is within a predetermined target range and, if not, decide in which direction the attachment 2 must be pivoted about the axis 21 to reduce the roll tendency to its target range, and which of the two actuators 11 must be extended and which retracted for this purpose. When and as long as the control circuit 27 is controlling one or both actuators 11 to drive a roll movement, it simultaneously moves the arm 15 on the side of the attachment that is lowered by this roll movement into a substantially undamped state in order to minimize the resistance to the roll movement.

[0032] When or shortly before the attachment 2 reaches the desired roll angle, the control circuit 27 terminates the actuation of the actuators 11. Simultaneously or with a short delay, the control circuit 27 closes the switching valve 26. The closing time can be selected, taking into account the damping effect provided by the pressure regulating valve 25 when the switching valve 26 is closed, such that the pivoting movement of the attachment 2 comes to a standstill at the desired roll angle. Reference sign

[0033] 1 Carrier vehicle 2 Attachment 3 Driver's cab 4 Front wheel 5 Inclined conveyor 6 Inlet opening 7 Frame 8 Reel 9 Cross conveyor screw 10 Joint 11 Actuator 12 Point of attachment 13 Point of attachment 14 Side plate 15 Arm 16 Wheel 17 Arm link 18 Actuating cylinder 19 Ground distance sensor 20 Wire bracket 21 Axle 22 Sensor 23 Pressure reservoir 24 Check valve 25 Pressure regulating valve 26 Switching valve 27 Control circuit 28 Fitting 29 Axle

Claims

1. An agricultural machine comprising a carrier vehicle (1) and a front attachment (2) which is pivotably guided on the carrier vehicle (1) about an axis (21) which extends in the direction of travel of the carrier vehicle (1), wherein, to the right and left of the axis (21), a respective support wheel (16) is connected to the front attachment (2) via a damped compressible arm (15), characterized in that a control circuit (27) is configured to decide whether a pivoting movement of the front attachment (2) about the axis (21) is desired or not and in the case in which the pivoting movement is desired, to switch that one of the arms (15) which is compressed by the pivoting movement out of a strongly damped compressible state into a substantially undamped state.

2. The agricultural machine according to claim 1, characterized in that the control circuit (27) is configured, when one of the arms (15) is compressed in the strongly damped compressible state, to treat a pivoting movement driven by this arm as a desired pivoting movement, and to switch the other arm (15) into the substantially undamped state.

3. The agricultural machine according to claim 1 or claim 2, characterized by an actuator (11) which engages on the carrier vehicle (1) and on the front attachment (2) in order to drive a pivoting movement between the carrier vehicle (1) and the front attachment (2) about the axis (21).

4. The agricultural machine according to claim 3, characterized in that the control circuit (27) is configured to treat a pivoting movement of the front attachment (2) about the axis (21) which is driven by the actuator (11) as a desired pivoting movement.

5. The agricultural machine according to one of the preceding claims, characterized in that the control circuit (27) is configured to switch the damping of an arm (15) during the course of a compression procedure thereof from the substantially undamped into the strongly damped state.

6. The agricultural machine according to one of the preceding claims, characterized in that each arm (15) comprises an actuating cylinder (18), and in that a chamber of the actuating cylinder (18) is connected to a reservoir (23) via a hydraulic circuit, and in that a flow resistance of the hydraulic circuit can be switched between the values corresponding to the substantially undamped state and to the strongly damped state.

7. The agricultural machine according to claim 6, characterized in that the actuating cylinder (18) is a single-acting actuating cylinder.

8. The agricultural machine according to claim 6 or claim 7, characterized in that the arm (15) has an arm member (17) which is articulated on the front attachment (2) at a first end and defines an axis of the support wheel (16) at a second end, and in that the actuating cylinder (18) is articulated on the arm member (17) and on the front attachment (2).

9. The agricultural machine according to one of claims 6 to 8, characterized in that the hydraulic circuit comprises a throttle point and an on / off valve (26) parallel to the throttle point.

10. The agricultural machine according to claim 9, characterized in that the hydraulic circuit furthermore comprises a check valve (24) parallel to the throttle point.

11. The agricultural machine according to claim 9 or claim 10, characterized in that the throttle point comprises a pressure regulating valve (25) which is controlled by the pressure at its connection which faces the actuating cylinder (18).

12. The agricultural machine according to one of the preceding claims, characterized in that each arm (15) is associated with a ground clearance meter (19) and the damping is controlled as a function of a measured ground clearance or of a difference between ground clearances measured by the ground clearance meters (19) on both sides of the axis (21).

13. The agricultural machine according to claim 12, insofar as it is dependent on claim 9, characterized in that the on / off valve (26) in the hydraulic circuit of one of the arms (15) is configured to open when a first threshold value of the ground clearance measured by the ground clearance meter (19) associated with the arm (15) or the difference between the ground clearance measured by the ground clearance meter (19) associated with the arm (15) and a ground clearance measured by a ground clearance meter on the opposite side of the axis (21) is exceeded and to close when a second, lower threshold value of the ground clearance or of the difference is undershot.