STEERING DEVICE, CONSTRUCTION MACHINE WITH A STEERING DEVICE AND METHOD FOR STEERING A STEERABLE MACHINE

Abstract

The invention relates to a steering device for a steerable machine, particularly a construction machine, comprising a steering element for manual input of steering commands, a steering actuator for driving a steering adjustment of a travel unit of the construction machine, and a transmission device, which is arranged between the steering element and the steering actuator, the transmission device including an actuator orbitrol for driving the steering actuator. Furthermore, the invention relates to a construction machine having such a steering device, as well as to a method for steering a steerable machine, particularly a construction machine.

Claims

1. A steering device for a steerable machine, particularly a construction machine, comprising: a steering element for manual input of steering commands: a steering actuator for driving a steering adjustment of a steering apparatus of a travel unit of the construction machine; and a transmission device, which is arranged between the steering element and the steering actuator, the transmission device including an actuator orbitrol for driving the steering actuator, wherein an upstream orbitrol is provided, said upstream orbitrol being arranged between the steering element and the actuator orbitrol in such a way that, on the one hand, it is driven by the steering element and, on the other hand, it drives the actuator orbitrol.

2. The steering device according to claim 1, wherein a hydraulic motor, which is connected to the upstream orbitrol via hydraulic lines and which has a movement transmission device on its output side towards the actuator orbitrol, particularly a shaft or a gearbox, is provided for driving the actuator orbitrol through the upstream orbitrol.

3. The steering device according to claim 1, wherein the upstream orbitrol is operatively connected with the actuator orbitrol via a closed hydraulic circuit.

4. The steering device according to claim 3, wherein a device for pressure pre-tensioning is provided in the closed hydraulic circuit.

5. The steering device according to claim 4, wherein hydraulic fluid is supplied to the device for pressure pre-tensioning via a pump.

6. The steering device according to claim 1, wherein the nominal diameters of connecting lines from the actuator orbitrol to the steering actuator are larger than the nominal diameters of connecting lines in the closed hydraulic circuit by at least the factor of 1.5, particularly by at least the factor of 2, and more particularly by at least the factor of 3.

7. The steering device according to claim 1, wherein the upstream orbitrol and the actuator orbitrol are supplied via separate pumps or via a common pump.

8. The steering device according to claim 1, wherein the upstream orbitrol forms an interrelated constructional unit with the steering element.

9. A construction machine, particularly a road construction machine, wherein it includes a steering device according to claim 1.

10. The construction machine according to claim 9, wherein it includes an operator platform, which, with respect to an operating position, is at least partly adjustable between two alternative operating positions (I, II), particularly comprising at least one of the following features: at least the steering element is adjustable, particularly displaceable, transversely to the working direction (A) of the construction machine; at least the steering element can be swivelled about a vertical axis; the steering element is part of a control platform or a control slide; which control platform or control slide can be swivelled transversely to the working direction (A) of the construction machine and/or about a vertical axis.

11. The construction machine according to claim 10, wherein the upstream orbitrol is integrated in the control platform or control slide and carried along with the control platform or control slide during an adjustment.

12. The construction machine according to claim 1, wherein the actuator orbitrol is arranged outside the operator platform, particularly stationary in its relative position to the drive engine of the construction machine and/or in the engine compartment and/or on the machine frame.

13. The construction machine according to claim 9, wherein the steering pump of the upstream orbitrol and/or the actuator orbitrol is driven via a pump transfer gear or a power take-off of the drive engine.

14. A method for steering a steerable machine, having a steering device, comprising the steps of: a) receiving, enhancing, and transferring a manual steering input by an upstream orbitrol; b) driving an actuator orbitrol by means of the upstream orbitrol; and c) driving a steering actuator by means of the actuator orbitrol.

15. The method according to claim 14, wherein the steering force applied to the steering actuator is also enhanced by the actuator orbitrol in step c).

Description

[0022] Below, the invention is illustrated in further detail with reference to the exemplary embodiments shown in the figures. In the schematic figures:

[0023] FIG. 1: is a side view of a large milling machine;

[0024] FIG. 2: is a side view of a compact milling machine;

[0025] FIG. 3: is a side view of a stabilizer/recycler;

[0026] FIG. 4: is a side view of a rubber wheeled roller;

[0027] FIG. 5: is a side view of a tandem roller with articulated steering;

[0028] FIG. 6: is a side view of a wheeled road paver;

[0029] FIG. 7: is a schematic diagram of a steering device of a first exemplary embodiment;

[0030] FIG. 8: is a schematic diagram of an adjustable operator platform having the steering device of FIG. 7;

[0031] FIG. 9: is a flow chart of a method according to the invention.

[0032] Like components are designated by like reference signs in the figures, however reference signs of recurring components may be omitted in some figures.

[0033] FIGS. 1 to 6 initially illustrate different construction machines 1 having a steering device according to the invention (not depicted in FIGS. 1 to 6). All construction machines 1 comprise travel units 2, which are steerable via at least one steering actuator (not shown in FIGS. 1 to 6). Furthermore, an operator platform 3 is respectively provided, from which the construction machine 1 is operated. The work direction is respectively indicated by the arrow A. All construction machines 1 shown in FIGS. 1 to 6 comprise a drive engine, which provides the drive power necessary for operation, and are self-propelled.

[0034] FIG. 1 shows specifically a road milling machine of the large milling machine type. The travel units 2 are crawler tracks, which are connected to the machine frame via lifting columns In the case of this machine type, the front as well as the rear travel units 2 are steerable.

[0035] FIG. 2 illustrates a compact or small milling machine having an open operator platform 3. In this case, the front wheels are likewise steerable, although machines that also permit steering of at least one of the rear wheels are known as well.

[0036] FIG. 3 shows a stabilizer/recycler. Steering occurs via an articulated steering system 4 between the front and rear part of the stabilizer/recycler. Furthermore, the rear set of wheels is likewise steerable, for example, via an Ackermann steering system.

[0037] In the case of the rubber-wheeled roller of FIG. 4, the front and/or rear travel units 2 are steerable. During operation, the rubber-wheeled roller moves in the forward and backward direction in an alternating manner.

[0038] In the case of the tandem roller shown in FIG. 5, steering occurs via an articulated joint arranged between the front carriage and the rear carriage. Alternatively, a respective pivot steering system may be provided for the front and rear travel units instead of an articulated steering system.

[0039] Finally, in the case of the road paver shown in FIG. 6, the two wheels attached to a tandem axle are steerable via a steering actuator.

[0040] Naturally, multiple steering actuators may be present in the machines mentioned above, which, however, are normally collectively controlled by the steering element.

[0041] FIG. 7 illustrates the general design of a steering device 5 according to the invention. Essential elements of the steering device 5 are a steering element 6, specifically a steering wheel in the present exemplary embodiment, an upstream obritrol 7, an actuator orbitrol 8, as well as a steering actuator 9. The steering actuator 9 is, for example, a hydraulic cylinder, which drives the adjustment of a steering apparatus 44, for example, an articulated joint, an Ackermann steering system or a turning/pivot steering system. In this connection, FIG. 7 illustrates that the upstream orbitrol 7, the actuator orbitrol 8, and the steering actuator 9 are arranged in series coming from steering element 6. Thus, the upstream orbitrol 7, the actuator orbitrol 8, and the interconnected hydraulic system form an enhancing transmission device 42. Because of this arrangement, a type of hydraulic remote control of the steering actuator 9 is achieved through the steering element 6.

[0042] Specifically, the steering element 6 is connected to the upstream orbitrol 7 via a suitable connecting element, for example, a connecting shaft or a connecting gear. The upstream orbitrol 7 is integrated in a closed hydraulic circuit 11. In addition to the connecting lines 12 and 13, said closed hydraulic circuit comprises a motor 14. On its output side, the motor 14 is connected to the actuator orbitrol 8 via an additional connecting device 15, for example, a shaft or a gear. The movement of the steering element 6 thus drives the adjusting movement of the upstream orbitrol 7. The hydraulic fluid flow triggered and enhanced through the adjustment of the upstream orbitrol 7 in the closed hydraulic circuit 11 ultimately drives motor 14. The connection to the actuator orbitrol 8 occurs on the output side of motor 14, so that overall the adjustment of the upstream orbitrol 7 by the steering element 6 drives an adjustment of the actuator orbitrol 8. The volume flow triggered through the adjustment of the actuator orbitrol 8 ultimately serves the steering adjustment of the steering actuator 9, through which the steering movements of the travel units 2 are driven.

[0043] The pumps 16A and 16B are provided for the hydraulic fluid supply of the upstream orbitrol 7 and the actuator orbitrol 8, which may alternatively both be supplied with hydraulic fluid through a common pump as well. The pumps 16A and 16B convey hydraulic fluid from a tank 17 to the upstream orbitrol 7 via the line 18 and to the actuator orbitrol 8 via a line 20. The pumps 16 are driven, for example, through a pump transfer gear or a power take-off of the drive engine and may, but do not necessarily have to, be used exclusively for supplying orbitrols 7 and 8. This is indicated by reference sign 43. Ideally, both pumps are driven through one and the same pump transfer gear or one and the same power take-off. Transfer from the upstream orbitrol to the tank 17 7 occurs via the line 19. The actuator orbitrol 8 is in fluid communication with the tank 17 via the line 20. Pressure relief valves 21 are respectively provided coming from the line 19 to the actuator orbitrol as well as on the output side to line 20. Two drivelines 22 and 23 are provided coming from the actuator orbitrol 8, which are in fluid communication with the steering actuator 9.

[0044] Further included in the closed hydraulic circuit 11 is a device 24 for pressure pre-tensioning as well as pressure limitation. It is arranged in line connection between the connecting lines 12 and 13 and comprises check valves 25 and, parallel thereto, pressure relief valves 26. The device 24 for pressure pre-tensioning thus enables, on the one hand, the desired pressure level to be maintained within the closed hydraulic circuit 11 and, on the other hand, serves to prevent excessive load conditions, which, for example, may occur if the operator attempts to further increase the steering angle via the steering element although the steering actuator 9 has reached the maximum steering angle. Due to the enhancing function of the upstream orbitrol 7, the pressure increases in the closed circuit, so that the present pressure protection becomes active. The device 24 for pressure pre-tensioning may be designed as an individual module, as indicated by the dashed box in FIG. 7. Alternatively, the entire pilot stage, comprising the upstream orbitrol 7, the line connections to the pump and to the tank, the device 24, as well as the connection to the actuator orbitrol 8, i.e., the part situated between the steering wheel 6 and actuator orbitrol 8, i.e., the pilot stage itself, may be designed as an individual module.

[0045] Furthermore, the unit consisting of the steering element 6 and the upstream orbitrol 7 may likewise form an individual module 27. In addition, as is known, the motor 14 is preferably designed as an individual module, as is the actuator orbitrol 8 (module 28). The individual modules 14, 24, 27, and 28 are connected via the connecting lines already mentioned above, where particularly the components of the connecting lines running between the individual modules, particularly coming from the module 27, may be designed as flexible hydraulic hoses.

[0046] A significant effect of the basic arrangement shown in FIG. 7 is especially the gradual enhancement of steering force of the actuating power introduced the via steering element 6 initially through the upstream orbitrol 7 towards the actuator orbitrol 8 and thence towards the steering actuator 9. Thus, it is particularly also possible to compensate or absorb pressure losses at the motor 14 and/or in the connecting lines, particularly lines 12 and 13, so that the steering forces to be applied on the steering wheel ideally only fluctuate very little or ideally even remain the same. As a result, an actuation situation is provided for the steering device 6 that is not affected by pressure losses/resistances in the lines 12 and 13 and/or at the motor 14, which is perceived as extremely comfortable by operators.

[0047] The basic principle shown in FIG. 7 is suitable in particular for integration in an operator platform 3 with an adjustable operating position. In this connection, the dashed line contained in FIG. 7 segments the steering device 5 into an operator platform part A and a machine frame part B. Those elements shown in the area of the operator platform part A are thus arranged within the operator platform or at least on it, particularly on an adjustable component, for example, an adjustable operator workstation, whereas the elements situated in the machine frame part B of FIG. 7 are preferably arranged on the machine frame, in an engine compartment, and/or at least stationary relative to a drive engine of the construction machine 1. FIG. 8 illustrates this in further detail. Reference is made to FIG. 7 with respect to the specific design of the steering device of FIG. 8.

[0048] FIG. 8 shows an operator platform 3 with a control slide 29, comprising a driver's seat 30, a control panel 31, the steering element 6, and a control column 32. The control slide 29 including these elements is movable transversely to the direction of work (Ar) via a guide device 33 between two end positions I and II. FIG. 8 shows the control slide 29 as being in position I, while position II is indicated with a dashed line. Instead of the control slide 29, for example, a control platform or the like, that is rotatable about a vertical axis, may be used. The line sections 12′ and 13′, which are part of the connecting lines 12 and 13 between the upstream orbitrol 7 and the actuator orbitrol 8 are designed as flexible lines, which are connected to the other sections of the connecting lines 12 and 13, which may also in part be stationary pipelines, via a connecting point 34. Viewed transversely to the working direction A, the connecting point 34 is arranged approximately centrally between the two positions I and II. When the aforementioned remote control of the steering actuator 9 occurs starting at the steering element 6, neither an electrical nor a mechanical interface is necessary for transmitting the steering command. No additional adaptation measures are necessary at the steering device 5 to adapt it to the different positions I and II because the flexible line sections 12′ and 13′ compensate any position changes between the upstream orbitrol 7 and the connecting point 34, respectively the actuator orbitrol 8.

[0049] Furthermore, FIG. 8 illustrates an additional benefit of the steering device 5. The upstream orbitrol 7 and the actuator orbitrol 8 each constitute an enhancement stage of the steering force applied via the steering element 6. The hydraulic-mechanical losses in the closed circuit 11 as well as at the motor 14, which, if using a displacement unit without an enhancement function, i.e., particularly a conventional gerotor, would add up directly as an additional actuation force to be applied on the steering element 6 and would be perceived as a disturbance by the operator, can be equalized for the operator through the upstream orbitrol 7. Due to the fact that the necessary input torque is low in the subsequent actuator orbitrol 8, only a fraction of the power which must be transmitted by the power path from the actuator orbitrol 8 to the steering actuator 9 and thence to the steering apparatus 44 must be transmitted in the closed circuit 11 of the upstream orbitrol 7. As a result, with a given hydraulic transmission in the closed circuit 11, a low pressure level and/or a low volume flow emerges (“minimal output”), which in turn enables the use of hydraulic hoses with small nominal diameters (e.g. 6 mm diameter) and/or the use of lower pressure resistances (e.g. hydraulic hoses of the “light series” instead of the “heavy-duty series”, as defined in DIN 20066), particularly in the hose sections 12 and 13. In contrast, in the present case, hoses of the heavy-duty series (DIN 20066) are preferably used in the “power path” (lines 22 and 23 between the actuator orbitrol 8 and the steering actuator 9), e.g. with a nominal diameter of 12 mm Due to the additional enhancement occurring through the actuator orbitrol 8, however, the hydraulic hoses having larger nominal diameters, which are to be used for connecting lines 20 and 23 to the steering actuator 9, can be kept comparatively short, which is also due to the spatial separation of the two orbitrols 7 and 8, which enables the actuator orbitrol 8 to be arranged in physical proximity to the steering actuator 9 and, thus, short distances with a high power transmission. This is also a significant advantage particularly with respect to costs.

[0050] Finally, FIG. 10 summarizes the essential steps of the method according to the invention. Initially a manual input of a steering command in step 35 causes driving 36 of an adjusting movement of the upstream orbitrol 7. This enables an enhancement 37 of the actuating force entered via the steering element 6. The enhanced actuating force is then transferred 38 via a hydrostat or closed hydraulic circuit for driving 39 the actuator orbitrol 8. Due to the adjustment of the actuator orbitrol achieved thereby, the actuating force is once again enhanced on the output side of the actuator orbitrol in step 40. Using the hydraulic flow thus obtained, finally, the actuating movement of the steering actuator 9 is driven 41. Thus, overall, this method provides for a two-stage, successive actuating force enhancement, although additional enhancement stages may be included here and are covered by the invention.