Electro-hydraulic lifting gear controller.

State of the art

p0001The invention is based on an electro-hydraulic device for controlling an articulated on a linkage of an agricultural working vehicle the implement according to the preamble of the main claim. It's been such a hoist control device known from DE-OS 26 47 077. in which a tractor is equipped with a slip control, the processed as additional controlled variable a position influence to limit the working depth of the plow. The tap position is carried out via a sensor which picks up the relative position of the plow carrying Hubwerksarmes between the casing of the tractor. The accuracy of the indirect detection of the working depth is insufficient for many applications, especially for large implements and uneven terrain. In addition, changes in depth, resulting in increase in slip by burying the drive wheels, not detected for position control. There is next to the plow other tools, including even those who are to perform at a certain distance above or on the ground, for a position control is not suitable. Especially with devices that are to run on the ground surface, is especially over uneven and soft ground, the risk of hard driving. Further, since a slip control by itself results in a relatively insta bile operation on a tractor, must be made to achieve accurate and stable operation by the influence of the additional control variable.

p0002Furthermore, from DE-AS 11 71 664, a tractor with a hoist control device known which operates to provide a constant working depth with a plow attached to the button. In this striving for high efficiency control device additional parameters are processed as control variables, including a hydrostatic transmission, the gear ratio is automatically adjusted and the performance of the vehicle engine is controlled by the fuel injection quantity. This device can indeed be a constant working depth and high efficiency achieved, with both a hard driving the tractor is avoided; but this device has the disadvantage that it builds very complex and therefore expensive. For a number of applications, it is therefore not suitable.

ADVANTAGES OF THE INVENTION

p0003The electrohydraulic device according to the invention for controlling an articulated on a hydraulic lift device with the characterizing features of the main claim has the advantage that it is a particularly simple slung with minimal effort, the working depth allows precisely regulating and protecting against a hard drive of the work vehicle control system. Here, the control system is also applicable for attachments to be run using a button on or above the ground surface and which ensure trouble-free operation even in soil surface and soft ground ist.Sie ​​therefore particularly suitable for large attachments and for use in other work tools as the plow. Further savings with it an expensive Tensile force so that it can be implemented relatively cheaply.

p0004The measures specified in the dependent claims, advantageous refinements and improvements of the main claim are possible means. A particularly advantageous and effective operation results when the process variable slip and working depth are processed in the manner specified in claim 4 in more detail. Extremely advantageous is a further application of the inventive device with a beet harvester according to claim 7. Further advantageous embodiments result from the description and drawings.

drawing

p0005An embodiment of the invention is illustrated in the drawing and explained in more detail in the following description. The single figure shows a simplified representation a tractor with an electrohydraulic device according to the invention for controlling an articulated on the hoist plow.

Description of the embodiment

p0006In the single figure is an agricultural work vehicle, a tractor 10 is shown, on the rear side by a conventional three-point linkage 11 a plow 12 is articulated as a working tool.

p0007The three-point linkage 11 is part of a lifting mechanism 13 which is operated by a hydraulic power lift 14 and thereby can adjust the plow 12 in its vertical position. The linkage 14 is located in a hydraulic circuit 15 with pump 16 and the electro-hydraulic control valve 17, control valve 17, linkage 14 and linkage 13 also form part of an electrohydraulic hoist controller 18th

p0008The control valve 17 is controlled by a controller operating as the electronic control unit 19, which can also be embodied in microprocessor technology. This control unit 19 are input to a first input 21 the signals of a reference value transmitter 22nd A second input 23 on the control unit 19 communicates witha touch sensor 24 in operative connection, which is arranged directly on the plow 12th This touch sensor 24 has an abrasive on the floor button 25, whose rotational position relative changes to the working depth of the plow 26 12 so that the push button 24 reports of the working depth of the plow 12 dependent signals to the control unit 19th The driven rear axle 27 of the tractor 10 is assigned to a speed encoder 28, whose signals are a measure of the drive speed of the rear wheel slip-prone 29th This speed sensor 28 is connected to a third input 31 of the electronic control device 19 in connection. A fourth input 32 of the control unit 19 receives signals from a radar sensor 33, the signals of which give a measure for the absolute speed of the tractor 10 off the ground.

p0009The operation of the electro-hydraulic control device is explained as follows, it being the function of which received only insofar as is necessary for understanding the invention.

p0010With the help of the setpoint generator 22, the operator for the control variables slip and working depth can certain setpoints select and enter the electronic controller 19th Here, the operator makes use of the fact that an optimum plowing with the tractor 10 is reached when a certain slippage occurs of a few percent and is not substantially exceeded.

p0011In the electronic control unit 19 is continuously determined from the signals of the speed sensor 28, the drive speed of the rear wheel 29, while the signals of the radar sensor 33 give a measure of the actual speed of the tractor above the ground. From these signals of the sensors 28, 33, the controller calculates 19 the slip occurring in each case, and compares it with the predetermined desired value for the slip. Is occurring on the tractor 10 slip less than the predetermined reference value, it controls the controller 19 via the control valve 17, the linkage 14 and the hoist 13 a lowering of the plow 12, whereby the working depth is increased 26 and thus also the result of increased soil resistance slip increases. The lowering movement of the plow 12 is terminated when the control deviation of the slip into set reaches the lower limit value. The signals of the push button 24 for the working depth 26 can thereby be processed in the electronic control unit to stabilize the slip-control loop.

p0012If on the other hand determined the tractor 10 from the sensors 28, 33 slip values ​​that exceed the preset target values ​​for the slip, so the Tastregelkreis greater extent to take effect. Here, the electro-hydraulic hoist control device 18 by the control unit 19 so affected that the working depth is 26 decreased steadily in accordance with the increase in slip. With the lifting of the plow 12 can be decreased and repatriate its size within an allowable range of the slip. Thus an oversized slip and beyond a fixed driving the tractor 10 during plowing can be prevented largely.

p0013To avoid constant adjusting movements of the lifting mechanism 13, it is of course possible to provide in particular adjustable enterable thresholds in the electronic control unit 19, when over- or undershooting the control device does not take effect. The combined processing of the control variables slip and working depth of the implement 12 results in a relatively easy-building and effective operating control device which is particularly easy to retrofit existing tractors 10th Especially not necessary to determine the tensile and compressive forces in the arms of the three-point linkage 11 made with, an expensive measuring device. Even with large attachments 12, the working depth can be 26 kept constant over a wide range with high accuracy while preventing a hard driving the tractor 10th

p0014Of course, modifications are possible to the controller shown, without departing from the spirit of the invention. Thus, the controlled variable slip can be found also on the non-driven front axle with an associated speed sensor. Instead of the slip signal, it may also be useful in the electronic control unit 19 to make the difference in speed from the signals of the sensors 28 33 and used as a control variable. Furthermore, it is readily possible to provide several switches 25 on the attachment 12 and to process the mean values ​​in the control unit 19th Furthermore, the influence of the control variables slip and working depth can be made adjustable in the control unit 19 in the manner of a mixed control. Furthermore, it is possible to associate the controller with a combined processing of slippage and working depth in place the rear-side hoist a front hoist. Since the control device according to the invention can also be used for attachments, which are used on or above the ground surface, it is understood that the term of the working depth and to change the controlled spacing of the attachment is understood above the soil surface always, the designated also as working height becomes.