Abstract
The disclosure relates to a road paver comprising a towing vehicle, at least one tow arm, a screed assembly attached to a tow point of the tow vehicle via the at least one tow arm, a leveling cylinder adapted to adjust a position, in particular a height, of the tow point, a screed lifting cylinder adapted to adjust a contact pressure of the screed assembly, a first measuring device adapted to determine a screed height of the screed assembly, a second measuring device adapted to determine an attack angle of the screed assembly, and a feedback control device adapted to control the leveling cylinder and the screed lifting cylinder. The disclosure further relates to a method for feedback controlling a position of a screed assembly and a use of a feedback control device for feedback controlling an attack angle and a screed height of a screed assembly.
Claims
1. A road paver comprising: a towing vehicle; at least one tow arm; a screed assembly attached to a tow point of the towing vehicle via the at least one tow arm; a leveling cylinder adapted to adjust a position of the tow point; a screed lifting cylinder adapted to adjust a contact pressure of the screed assembly; a first measuring device adapted to determine a screed height of the screed assembly; a second measuring device adapted to determine an attack angle of the screed assembly; and a feedback control device adapted to control the leveling cylinder and the screed lifting cylinder.
2. The road paver according to claim 1, wherein the position comprises a height of the tow point.
3. The road paver according to claim 1, wherein the feedback control device has a first controller adapted to control the leveling cylinder based on a control deviation of the screed height, and a second controller adapted to control the screed lifting cylinder based on a control deviation of the attack angle.
4. The road paver according to claim 1, wherein the feedback control device has a first controller adapted to control the leveling cylinder based on a control deviation of the screed height, and a second controller adapted to control the screed lifting cylinder based on a control deviation of the screed height.
5. The road paver according to claim 1, wherein the feedback control device has a multi-variable controller adapted to control the leveling cylinder and the screed lifting cylinder based on a control deviation of the screed height and a control deviation of the attack angle.
6. The road paver according to claim 1, wherein the second measuring device comprises a first inclination sensor arranged on the screed assembly and a second inclination sensor arranged on the towing vehicle, wherein the first inclination sensor is adapted to determine an inclination angle of the screed assembly relative to a horizontal plane, wherein the second inclination sensor is adapted to determine an inclination angle of the towing vehicle relative to the horizontal plane, and wherein the second measuring device is adapted to determine the attack angle of the screed assembly from the inclination angle of the screed assembly and the inclination angle of the towing vehicle.
7. The road paver according to claim 1, wherein the second measuring device comprises a rotational angle sensor which is arranged at the tow point of the towing vehicle.
8. The road paver according to claim 1, wherein the screed assembly comprises a base screed and an extension part, wherein the extension part is arranged at least partially offset from the base screed in a paving direction of the road paver, and wherein the base screed and the extension part have the same attack angle.
9. A method for feedback controlling a position of a screed assembly attached to a tow point of a road paver, comprising: determining a screed height of the screed assembly; determining an attack angle of the screed assembly; adjusting the position of the tow point based on the determined screed height; and adjusting a contact pressure of the screed assembly based on the determined attack angle.
10. The method according to claim 9, wherein adjusting the position of the tow point comprises adjusting a height of the tow point.
11. The method according to claim 9, wherein adjusting the position of the tow point and adjusting the contact pressure of the screed assembly occur during operation of the road paver.
12. The method according to claim 9, wherein adjusting the position of the tow point and adjusting the contact pressure of the screed assembly occur automatically.
13. The method according to claim 9, wherein adjusting the position of the tow point and adjusting the contact pressure of the screed assembly occur automatically by a feedback control device.
14. The method according to claim 9, wherein the determined screed height and the determined attack angle are fed to a feedback control device of the road paver, and wherein the feedback control device comprises a multi-variable controller for controlling the screed height and controlling the attack angle.
15. The method according to claim 9, wherein the determined screed height and the determined attack angle are fed to a feedback control device of the road paver, wherein the feedback control device comprises first and second separate controllers, and wherein the first controller is used to control the screed height, and the second controller is used to control the attack angle.
16. The method according to claim 9, wherein adjusting the position of the tow point is additionally based on the determined attack angle, and adjusting the contact pressure of the screed assembly is additionally based on the determined screed height.
17. The method according to claim 9, wherein adjusting the position of the tow point occurs by use of a leveling cylinder, and adjusting the contact pressure of the screed assembly occurs by use of a screed lifting cylinder.
18. A method for feedback controlling a position of a screed assembly of a road paver, the method comprising using a feedback control device for feedback controlling an attack angle of the screed assembly of the road paver and for feedback controlling a screed height of the screed assembly.
19. The method according to claim 18, wherein the feedback control device comprises a multi-variable controller, the multi-variable controller being used to feedback control the attack angle of the screed assembly and to feedback control the screed height of the screed assembly.
20. The method according to claim 18, wherein the feedback control device comprises a first controller and a second controller, wherein the first controller is used to feedback control the screed height of the screed assembly and the second controller is used to feedback control the attack angle of the screed assembly.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0062] The disclosure is explained in more detail below with reference to embodiments.
[0063] FIG. 1 shows a schematic side view of a road paver with a screed assembly according to an embodiment of the disclosure;
[0064] FIG. 2 shows a schematic top view of a road paver with a screed assembly according to an embodiment of the disclosure;
[0065] FIG. 3 shows a schematic side view of a screed assembly and a tow arm in a first installation situation according to an embodiment of the disclosure;
[0066] FIG. 4 shows a schematic side view of a screed assembly and a tow arm in a second installation situation according to an embodiment of the disclosure;
[0067] FIG. 5 shows a schematic side view of a screed assembly and a tow arm in a third installation situation according to an embodiment of the disclosure;
[0068] FIG. 6 shows a feedback control circuit known from the prior art for feedback controlling the position of a screed assembly;
[0069] FIG. 7 shows a feedback control circuit for feedback controlling the position of a screed assembly according to an example embodiment of the disclosure;
[0070] FIG. 8 shows a feedback control circuit for feedback controlling the position of a screed assembly according to an example embodiment of the disclosure; and
[0071] FIG. 9 shows a feedback control circuit for feedback controlling the position of a screed assembly according to an example embodiment of the disclosure.
DETAILED DESCRIPTION
[0072] FIG. 1 shows a road paver 1 according to an embodiment of the disclosure. The road paver 1 comprises a towing vehicle 2 and a screed assembly 3. The screed assembly 3 is connected to the towing vehicle 2 by means of two tow arms 4, each of which extends laterally on the road paver 1. The tow arms 4 are pivotally connected to the towing vehicle 2 at tow points 5. The screed assembly 3 is arranged behind the towing vehicle 2 with respect to the paving direction 100 and is towed behind the towing vehicle 2 by the tow arms 4. A material hopper 6 for receiving paving material is arranged in the front area of the road paver 1. The paving material is transported to the rear by a material transport device of the towing vehicle 2 against the paving direction 100 and presented to the screed assembly 3. A transverse distribution device 7 may be provided in the rear area of the towing vehicle 2, which distributes the paving material orthogonally to the paving direction 100 in front of the screed assembly 3.
[0073] A leveling cylinder 8 is arranged on each side of the road paver 1. The leveling cylinder 8 is connected to the respective tow arm 4 via an intermediate piece 9. The position, in particular the height, of the tow points 5 may be adjusted using the leveling cylinders 8. Two screed lifting cylinders 10 are arranged in the rear area of the road paver 2. The screed lifting cylinders 10 are attached to a rear area of the respective tow arm 4. Alternatively, the screed lifting cylinders 10 may also be connected directly to the screed assembly 3. The screed lifting cylinders 10 may be used to adjust the position, in particular the height, and the contact pressure of the screed assembly 3.
[0074] FIG. 2 shows a top view of a road paver 1 according to an embodiment of the disclosure. The tow arms 4 are arranged on the side of the towing vehicle 2. The screed assembly 3 comprises a base screed 11 and two extension parts 12. The extension parts 12 are arranged behind the base screed 11 in the paving direction 100. Alternatively, the extension parts 12 may be arranged in front of the base screed 11 in the paving direction 100. The extension parts 12 are arranged laterally next to the base screed 11 in the transverse direction 200. The extension parts 12 may be retracted and extended in the transverse direction 200 so that the width of the screed assembly 3 changes. The width of the screed assembly 3 is the extension of the screed assembly 3 in the transverse direction 200. The width of the screed assembly may be increased by assembling widening parts on the extension parts.
[0075] FIG. 3 shows a schematic side view of the screed assembly 3 and the tow arm 4 in a first installation situation on a flat subgrade 13. The extension part 12 is arranged behind the base screed 11 in the paving direction 100. The extension part 12 and the base screed 11 have the same attack angle 14. The dashed line represents the desired installation height 15 of the finished paving material. The base screed 11 and the extension part 12 are arranged offset in the vertical direction. The vertical offset 16 between base screed 11 and extension part 12 is adjusted so that the extension part height 18 corresponds to the base screed height 17. This is usually adjusted manually before installation.
[0076] FIG. 4 shows the screed assembly 3 and the tow arm 4 in a second installation situation. Compared to FIG. 3, the tow point 5 is higher. This results in a larger attack angle 14. The attack angles 14 of the base screed 11 and the extension part 12 are still identical. As may be seen from FIG. 4, the base screed height 17 corresponds to the desired installation height 15. Due to the fact that the extension part 12 is arranged behind the base screed 11 in the paving direction 100, the rear edge of the extension part 12 sinks further than the rear edge of the base screed 11. Accordingly, the extension part height 18 is smaller than the base screed height 17. This leads to unevenness in the finished paving material in the transverse direction.
[0077] FIG. 5 shows the screed assembly 3 and the tow arm 4 in a third installation situation. The subgrade 13 has a subgrade inclination 19. Only the base screed 11 is shown in FIG. 5. A leveling cylinder 8 is attached in the front area of the tow arm 4, which adjusts the position of the tow point 5. A screed lifting cylinder 10 is attached in the rear area of the tow arm 4, which adjusts the contact pressure of the screed assembly 3 on the paving material. In the position of the screed assembly 3 shown in FIG. 5, the base screed height 17 corresponds to the desired installation height 15. The base screed 11 has an absolute base screed inclination 20. The absolute base screed inclination 20 is the inclination of the base screed 11 relative to a horizontal plane. The attack angle 14 of the base screed 11 is calculated from the absolute base screed inclination 20 minus the subgrade inclination 19.
[0078] FIG. 6 shows a feedback control circuit known from the prior art with a feedback control device 50 for feedback controlling the position of a screed assembly 3. The screed transfer behavior 51 is influenced by the screed lifting cylinder pressure 52, the subgrade height 53 and the levelling cylinder position 54. The screed lifting cylinder pressure 52 and the subgrade height 53 are external input parameters. Another input parameter is the desired installation height 15. A screed height 55 and an attack angle 14 are established depending on the screed lifting cylinder pressure 52, the subgrade height 53 and the leveling cylinder position 54. The screed height 55 is measured by a measuring device 56 and transmitted to a controller 57. The controller 57 compares the desired installation height 15 with the measured screed height 55 and, if necessary, effects a change in the levelling cylinder position 54. The controller 57 only reacts to a change in the screed height 55. It does not react to a change in the attack angle 14.
[0079] FIG. 7 shows a control circuit according to an example embodiment of the present disclosure with a feedback control device 50 for feedback controlling the position of a screed assembly 3. As in FIG. 6, the screed transfer behavior 51 is influenced by the screed lifting cylinder pressure 52, the subgrade height 53 and the leveling cylinder position 54. In comparison to the control circuit shown in FIG. 6, only the subgrade height 53 is an external input parameter. The desired installation height 15 and the desired attack angle 58 are specified as target values. The target value for the installation height 15 and/or the target value for the attack angle 58 may be specified by manual user input. The target value for the installation height 15 and/or the target value for the attack angle 58 may be specified or suggested by a control system, in particular depending on the paving material. The target value for the installation height 15 and/or the target value for the attack angle 58 may be determined based on stored values from previous construction measures. A screed height 55 and an attack angle 14 of the screed assembly 3 are adjusted based on the screed lifting cylinder pressure 52, the subgrade height 53 and the leveling cylinder position 54. The screed height 55 of the screed assembly 3 is measured by means of a first measuring device 59 and transmitted to a first controller 60. The first controller 60 compares the desired installation height 15 with the measured screed height 55 and, if necessary, effects a change in the leveling cylinder position 54. The attack angle 14 of the screed assembly 3 is measured by means of a second measuring device 61 and transmitted to a second controller 62. The second controller 62 compares the desired attack angle 58 with the measured attack angle 14 and, if necessary, effects a change in the screed lifting cylinder pressure 52. The first controller 60 responds to a change in the screed height 55 and the second controller 62 responds to a change in the attack angle 14.
[0080] FIG. 8 shows a control circuit according to a further example embodiment of the present disclosure with a feedback control device 50 for feedback controlling the position of a screed assembly 3. Compared to the control circuit shown in FIG. 7, the control circuit in FIG. 8 has only a first measuring device 59. The first measuring device 59 measures the screed height 55 of the screed assembly 3 and transmits it to the first controller 60 and the second controller 62. The first controller 60 compares the desired installation height 15 with the measured screed height 55 and, if necessary, effects a change in the leveling cylinder position 54. The second controller 62 compares the desired installation height 15 with the measured screed height 55 and, if necessary, effects a change in the screed lifting cylinder pressure 52.
[0081] FIG. 9 shows a control circuit according to a further example embodiment of the present disclosure with a feedback control device 50 for feedback controlling the position of a screed assembly 3. Compared to the control circuit shown in FIG. 7, the control circuit in FIG. 9 has a multi-variable controller 63. The first measuring device 59 measures the screed height 55 of the screed assembly 3 and transmits it to the multi-variable controller 63. The second measuring device 61 measures the attack angle 14 of the screed assembly 3 and transmits it to the multi-variable controller 63. The multi-variable controller 63 compares the desired installation height 15 with the measured screed height 55 and uses this to calculate a control deviation of the screed height. The multi-variable controller 63 compares the desired attack angle 58 with the measured attack angle 14 and uses this to calculate a control deviation of the attack angle. Based on the control deviation of the screed height and the control deviation of the attack angle, the multi-variable controller 63 effects a change in the screed lifting cylinder pressure 52 and the leveling cylinder position 54, if necessary. The multi-variable controller 63 may be a MIMO controller (multiple-input-multiple-output controller).
[0082] As one skilled in the art would understand, the feedback control device 50, the first measuring device 59, the first controller 60, the second measuring device 61, the second controller 62, the multi-variable controller 63, as well an any other control system, unit, machine, apparatus, element, sensor, device, component, system, subsystem, arrangement, or the like described herein may individually, collectively, or in any combination comprise appropriate circuitry, such as one or more appropriately programmed processors (e.g. one or more microprocessors including central processing units (CPU)) and associated memory, which may include stored operating system software and/or application software executable by the processor(s) for controlling operation thereof and/or for performing the particular algorithms represented by the various functions and/or operations described herein, including interaction and/or cooperation between any such feedback control device, measuring device, controller, control system, unit, machine, apparatus, element, sensor, device, component, system, subsystem, arrangement, or the like. One or more of such processors, as well as other circuitry and/or hardware, may be included in a single ASIC (Application-Specific Integrated Circuitry), or several processors and various circuitry and/or hardware may be distributed among several separate components, whether individually packaged or assembled into a SoC (System-on-a-Chip).
