Road paver with screed leveling feedback control

Abstract

The invention relates to a road paver (1). Comprising a tractor (2), at least one traction arm (4), a screed assembly (3) attached to a traction point (5) of the tractor (2) via the at least one traction arm (4), a leveling cylinder (8) adapted to adjust the position, in particular height, of the traction point (5), a screed lift cylinder (10) adapted to adjust the contact pressure of the screed assembly (3), a first measuring device (59) adapted to determine the screed height (55) of the screed assembly (3), second measuring means (61) adapted to determine the angle of attack (14) of the screed assembly (3); and feedback control means (50) adapted to control the leveling cylinder (8) and the screed lift cylinder (10). The invention also relates to a method for feedback control of the position of a screed assembly (3) and to the use of a feedback control device (50) for feedback control of an angle of attack (14) and a screed height (55) of a screed assembly (3).

Description

Technical Field

[0001] The present invention relates to the technical field of road paving machines. In particular, the present invention relates to a road paver having a screed for compacting paving material and a method for controlling such a road paver. Background Art

[0002] A method for determining a change in the angle of attack of a screed is known from DE 10 2021 107 447 A1. DE 19647 150 A1 shows a method for controlling the screed height of a screed. A method for controlling the paving thickness and quality of an asphalt paving material is known from EP 2 366 831 B1.

[0003] In the leveling feedback control known in the prior art, the screed height of the screed is detected and adjusted with the aid of leveling cylinders. During paving, the screed lift cylinders are usually in a floating position. In order to influence static compaction, a constant pressure can be set on the rod side of the screed lift cylinders. The screed bottom surface is inclined towards the subgrade. This inclination is called the angle of attack and is adjusted to a predetermined value at the start by the screed lift cylinders, etc. The angle of attack influences the quality of the paving result, in particular the compaction of the paved material and the resulting surface appearance. It is therefore advantageous to maintain a constant angle of attack during operation.

[0004] Changes in screed height, changes in the speed of the road paver installation and / or changes in the paving material may affect the change in the screed angle of attack. Too much or too little angle of attack may lead to poor paving results. Especially for road pavers with extension screeds, a poor angle of attack may lead to different screed heights between the bottom screed and the extension, resulting in uneven roads in the lateral direction.

[0005] In the systems known from the prior art, the screed height is adjusted continuously only by adjusting the leveling cylinders. But this means that the angle of attack is not constant but is determined by the current position of the leveling cylinders as well as the paving material properties and other environmental conditions. The angle of attack is defined by the position of the leveling cylinders and the layer thickness geometry. Summary of the invention

[0006] The object of the present invention is to keep the attack angle of the screed as constant as possible during operation, thereby improving the paving quality.

[0007] The paving results can be significantly improved by the invention. By constantly checking and adjusting the angle of attack of the screed assembly, the longitudinal flatness of the paving material can be improved. When using an extended screed, the transverse flatness of the paving material can also be improved by the invention. In addition, the compaction effect can be improved by the constant angle of attack. The invention also increases process reliability, since no manual monitoring or manual readjustment of the angle of attack is required. The system can automatically react to changes in the paving material, thus reducing paving errors.

[0008] A first aspect of the invention relates to a road paver having a tractor, at least one tractor arm, a screed assembly, a leveling cylinder, a screed lifting cylinder, a first measuring device, a second measuring device and a feedback control device. The screed assembly is attached to a traction point of the tractor via at least one tractor arm. The leveling cylinder is used to adjust the position, in particular the height, of the traction point. The screed lifting cylinder is used to adjust the contact pressure of the screed assembly. The contact pressure refers to the pressure exerted by the screed assembly (in particular due to its own weight) on the paving material. The contact pressure of the screed assembly may come from the own weight of the screed assembly and the force of the screed lifting cylinder. The force from the screed lifting cylinder may produce a loading or unloading effect. The first measuring device is suitable for determining the screed height of the screed assembly. The second measuring device is suitable for determining the angle of attack of the screed assembly. The feedback control device is suitable for controlling the leveling cylinder and the screed lifting cylinder.

[0009] The screed assembly may be configured to form a road paver together with a tractor. The screed assembly may be attached to the tractor. The screed assembly may be configured to be towed behind the tractor in a paving direction. The screed assembly may be configured to compact paving material, in particular asphalt paving material, on a roadbed. The screed assembly may be configured to level paving material, in particular asphalt paving material, on a roadbed.

[0010] The transverse direction is defined as a direction extending in a horizontal plane and perpendicular to the paving direction. The paving direction is the direction in which the paver moves during paving. The lateral direction or width direction may be a direction parallel to the transverse direction.

[0011] The screed assembly may comprise a bottom screed and at least one extension, preferably two extensions. In the context of the present invention, the bottom screed is also referred to as a primary screed. In the context of the present invention, the extensions are also referred to as secondary screeds. The extensions may be arranged laterally to the left and to the right of the bottom screed in the transverse direction. The extensions may be arranged behind the bottom screed in the paving direction. Alternatively, the extensions may also be arranged in front of the bottom screed in the paving direction.

[0012] The bottom screed plate may include a planing sheet of the bottom screed plate for contacting the paving material. The extension may include a planing sheet support and an extension planing sheet. The extension planing sheet may be configured to contact the paving material. The extension planing sheet may be attached to the planing sheet support so as to be able to tilt about a tilting axis. The screed plate assembly may include a height adjustment device. The screed plate assembly may include a tilting device. The height adjustment device may be adapted to lower or raise one or more extensions relative to the bottom screed plate. The height adjustment device may be configured to lower or raise the planing sheet support relative to the bottom screed plate. The tilting device may be configured to change the tilt angle of the extension planing sheet about the tilting axis. The tilting axis may extend in a transverse direction. The tilting axis may extend horizontally.

[0013] The screed height of the screed assembly may denote the vertical distance between the rear edge of the screed assembly, in particular the rear edge of the screed board of the screed assembly, and a reference point, such as a reference point on the roadbed. The screed height of the base screed may denote the vertical distance between the rear edge of the base screed, in particular the rear edge of the base screed board, and a reference point, such as a reference point on the roadbed. The screed height of the extension may denote the vertical distance between the rear edge of the extension, in particular the rear edge of the extension board, and a reference point, such as a reference point on the roadbed. The term "rear edge" refers to the rearmost edge of the base screed or the extension in the paving direction. The height of the rear edge or the screed height determines the installation height of the paving material.

[0014] The angle of attack of the screed assembly may denote the inclination of the screed assembly, in particular of the shaver board of the screed assembly, relative to the inclination of the roadbed. For a horizontal roadbed, the angle of attack of the screed assembly corresponds to the absolute inclination of the shaver board. The term "absolute inclination" means that the inclination is determined relative to a horizontal plane. For an inclined roadbed, the angle of attack corresponds to the difference between the absolute inclination of the shaver board and the absolute inclination of the roadbed.

[0015] The angle of attack of the bottom screed may refer to the inclination of the bottom screed, in particular the bottom screed shaver board, relative to the inclination of the roadbed. The angle of attack of the extension may refer to the inclination of the extension, in particular the extension shaver board, relative to the inclination of the roadbed.

[0016] The screed assembly can be rotatably attached to a towing point of a road paver, in particular a towing point of a tractor of the road paver, via at least one towing arm. The screed assembly can be rotatably attached to a towing point of a road paver, in particular a towing point of a tractor, via two towing arms. The towing arms can be arranged on the sides of the tractor. One towing arm can be arranged on each side of the tractor. The height of the towing point can be adjusted with a leveling cylinder. The paver can have two towing arms and two leveling cylinders. Each leveling cylinder can be assigned to a towing arm. The leveling cylinder can be connected to the respective towing arm. The connection between the leveling cylinder and the towing arm can be made directly or via an intermediate piece. The leveling cylinder and the towing arm can be arranged laterally on the road paver relative to the transverse direction of the road paver. There can be a towing arm and a leveling cylinder on each side of the road paver. Features described in the further course of the application in relation to the leveling cylinders also relate to the two leveling cylinders, even if not explicitly mentioned.

[0017] The screed assembly, in particular the bottom screed, can be connected to the tractor by means of screed lift cylinders. The screed assembly, in particular the bottom screed, can be connected to the tractor by means of two screed lift cylinders. One screed lift cylinder or a plurality of screed lift cylinders can be used to vertically raise or lower the screed assembly. One screed lift cylinder or a plurality of screed lift cylinders can be used to adjust the contact pressure of the screed assembly on the paving material. Features described below in relation to the screed lift cylinders also apply to the two screed lift cylinders, even if not explicitly mentioned.

[0018] The screed lift cylinder may be directly connected to the screed assembly or the bottom screed plate. The screed lift cylinder may be indirectly connected to the screed assembly or the bottom screed plate. The screed lift cylinder may be attached to the trailing arm, in particular to the rear region of the trailing arm.

[0019] The road paver may have a material hopper. The material hopper may be adapted to receive paving material. The material hopper may be arranged in front of the screed assembly in the paving direction.

[0020] The road paver may have a control device. The control device may be adapted to control a screed lift cylinder. The control device may be adapted to control a leveling cylinder. The control device may be adapted to control a screed lift cylinder and a leveling cylinder. The control device may be part of a feedback control device.

[0021] The feedback control device may have a first controller. The first controller may be adapted to control one or more leveling cylinders based on a control deviation of the screed height. The control deviation of the screed height is the difference between a target value of the screed height, for example a desired installation height, and an actual value of the screed height. The control deviation of the screed height may be determined based on the target value of the screed height and the actual screed height determined by the first measuring device. The target value of the screed height may be specified by manual input by a user. The target value of the screed height may be specified or suggested by the control system, in particular depending on the paving material. The target value of the screed height may be determined based on values ​​stored from previous construction measurements. The target value of the screed height may be derived from a road construction plan. The target value of the screed height may be entered manually. The target value may be taken directly from digital planning data.

[0022] The feedback control device may have a second controller. The second controller may be adapted to control one or more screed lift cylinders based on a control deviation of the angle of attack. The control deviation of the angle of attack is the difference between a target value of the angle of attack, such as a desired angle of attack, and an actual value of the angle of attack. The control deviation of the angle of attack may be determined based on the desired value of the angle of attack and the actual angle of attack determined by the second measuring device. The second controller may be adapted to calculate the required pressure in the screed lift cylinder based on the determined actual angle of attack. The target value of the angle of attack may be specified by manual input by a user. The target value of the angle of attack may be specified or suggested by the control system, in particular depending on the paving material. The target value of the angle of attack may be determined based on values ​​stored in previous construction measurements. The target value of the angle of attack may be selected to match the height setting of the extension. This allows a good degree of compaction to be adjusted and thus a good paving pattern to be obtained.

[0023] The feedback control device may have a first controller. The first controller may be adapted to control the leveling cylinder based on a control deviation of the screed height. The feedback control device may have a second controller. The second controller may be adapted to control the screed lifting cylinder also based on a control deviation of the screed height.

[0024] The first controller may be a SISO controller (single input single output controller), such as a P controller (proportional controller), a PI controller (proportional integral controller) or a PID controller (proportional integral derivative controller). The first controller may be a robust controller, such as an H-infinity controller. The second controller may be a SISO controller, such as a P controller, a PI controller or a PID controller. The second controller may be a robust controller, such as an H-infinity controller.

[0025] The feedback control device may have a multivariable controller. The multivariable controller may be 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 angle of attack. Both feedback control variables, namely the angle of attack and the screed height, may be controlled by one controller, namely the multivariable controller. In this way, the interaction between the two control variables (angle of attack and screed height) and the two drive variables (leveling cylinder and screed lifting cylinder) may be considered. The multivariable controller may also be called a MIMO controller (multiple-input multiple-output controller). The multivariable controller may be an H-infinity controller, an LQ controller or an LQG controller.

[0026] In systems known from the prior art, the current installation speed is usually included in the feedback control. With the feedback control device according to the invention, this is not necessary. The feedback control device, in particular a multivariable controller, may be adapted to output no other control variables than the angle of attack and the screed height. The feedback control device, in particular a multivariable controller, may be adapted to control the screed lift cylinders and the leveling cylinders based only on the angle of attack and the screed height, in particular based on a target / actual comparison of the angle of attack and a target / actual comparison of the screed height. The feedback control device, in particular a multivariable controller, may be adapted to control the screed lift cylinders and the leveling cylinders based only on the measured values ​​from the first measuring device and the second measuring device. The feedback control device, in particular a multivariable controller, may be adapted to control the screed lift cylinders and the leveling cylinders without taking the installation speed into account. The feedback control device may be adapted to select the control parameters depending on the installation speed. The feedback control device may be adapted to control the screed lift cylinders and the leveling cylinders depending on the installation speed. The feedback control device may be adapted to apply a large controller gain at high installation speeds and a small controller gain at low installation speeds. The terms high, low, large, small should be understood in relation to each other.

[0027] The first measuring device may be a rangefinder, such as a laser rangefinder, a mechanical probe or an acoustic rangefinder.

[0028] The second measuring device may have a first inclination sensor. The second measuring device may have a second inclination sensor. The second measuring device may have a first inclination sensor and a second inclination sensor. The first inclination sensor may be arranged on the screed assembly. The second inclination sensor may be arranged on the tractor.

[0029] The first tilt sensor may be adapted to determine the tilt angle of the screed assembly relative to the horizontal plane. The second tilt sensor may be adapted to determine the tilt angle of the tractor relative to the horizontal plane. The second measuring device may be adapted to determine the angle of attack of the screed assembly from the tilt angle of the screed assembly and the tilt angle of the tractor.

[0030] The first tilt sensor may be adapted to determine the tilt angle of the bottom screed relative to a horizontal plane. The first tilt sensor may be adapted to determine the tilt angle of the extension relative to a horizontal plane. The tilt angle of the tractor may correspond to the inclination of the roadbed. Alternatively, the inclination of the roadbed or the tilt angle of the tractor may be determined based on a digital terrain model. In this case, a second tilt sensor on the tractor is not necessary. The tilt angle may be calculated based on the inclination angle measured by the first tilt sensor and the inclination of the roadbed determined based on the terrain model. Multiple first tilt sensors may be attached so that the tilt angle of the screed assembly is determined and controlled at multiple points, for example, at two extensions. Multiple second tilt sensors may be attached so that the tilt angle of the tractor may be determined based on an average value of the second tilt sensors.

[0031] The second measuring device may have an inclination sensor attached to the bottom screed plate or the extension. The inclination sensor may be configured to determine an inclination angle of the bottom screed plate or the extension relative to a horizontal plane. The control device of the road paver may be adapted to determine the inclination of the roadbed based on the digital terrain model. The control device may be adapted to determine an angle of attack of the bottom screed plate based on the determined inclination angle of the bottom screed plate and the inclination of the roadbed. The control device may be adapted to determine an angle of attack of the extension based on the determined inclination angle of the extension and the inclination of the roadbed.

[0032] The second measuring device may have a rotation angle sensor. The rotation angle sensor may be arranged at the towing point of the tractor. The rotation angle sensor may be adapted to measure the inclination of the towing arm relative to the inclination of the tractor. The screed assembly may be rigidly connected to the towing arm. The angle of attack of the screed assembly may then be determined via the inclination of the towing arm. The rotation angle measured at the towing point may correspond to the angle of attack.

[0033] The second measuring device may have a first rotation angle sensor on a first towing arm attached to one side of the towing vehicle and a second rotation angle sensor on a second towing arm attached to the other side of the towing vehicle. The angle of attack of the screed assembly may then be determined from the average of the first and second rotation angle sensors.

[0034] The feedback control device and / or the control device may be configured to filter environmental influences. The feedback control device and / or the control device may be configured to filter influences from vibrations and / or temperature fluctuations. Advanced signal processing methods, such as Kalman filters or state observers, may be used to achieve this purpose.

[0035] The screed assembly may have a base screed and at least one extension. The extension may be arranged at least partially offset from the base screed in the paving direction of the road paver. The extension may be arranged at least partially in front of or behind the base screed in the paving direction of the road paver. The extension may be arranged completely in front of or behind the base screed in the paving direction of the road paver. The base screed and the extension may have the same angle of attack. The extension may be arranged laterally next to the base screed with respect to the transverse direction. The screed assembly may have two extensions. The extensions may be arranged on both sides of the base screed with respect to the transverse direction. The extensions may be telescopic laterally, so that the width of the screed assembly may be changed. The width of the screed assembly corresponds to the extension of the screed assembly in the transverse direction. The extension may have a vertical offset relative to the base screed. The vertical offset may be adjusted by a height adjustment device. Due to the geometric arrangement of the base screed and the extension, the vertical offset is only optimal at a specific angle of attack. If the angle of attack changes, the vertical offset must be adjusted. Otherwise, the bottom screed and the extension will have different screed heights. This will lead to indentations of the extension in the installation layer and unevenness in the transverse direction. The screed assembly can also consist of only the bottom screed, without the extension.

[0036] The screed lift cylinder can have a pressure control on the piston side. The screed lift cylinder can be adjusted so that it allows the screed assembly to be released and loaded. This can correct for too small or too large an angle of attack. If the angle of attack is too small or too large, the feedback control adjusts the angle of attack.

[0037] A second aspect of the invention relates to a method for feedback control of the position of a screed assembly of a road paver. The screed assembly is attached to a towing point of the road paver, in particular by means of at least one towing arm. The method comprises determining a screed height of the screed assembly and determining an angle of attack of the screed assembly. The method further comprises adjusting the position, in particular the height, of the towing point based on the determined screed height. The method further comprises adjusting the contact pressure of the screed assembly depending on the determined angle of attack.

[0038] Adjusting the position of the traction point may include adjusting the height and vertical position of the traction point.

[0039] The determination of the screed height may be performed continuously. The determination of the angle of attack may be performed continuously. The determination of the screed height and the determination of the angle of attack may be performed simultaneously. The determination of the screed height and / or the angle of attack may be performed periodically.

[0040] The adjustment of the position of the traction point can be performed continuously. The adjustment of the contact pressure can be performed continuously. The adjustment of the position of the traction point and the adjustment of the contact pressure can be performed simultaneously. The adjustment of the position of the traction point and / or the adjustment of the contact pressure can be performed periodically.

[0041] The position of the traction point can be adjusted later than the contact pressure. For example, the screed height can be determined first, and the position of the traction point can be adjusted accordingly. Then the angle of attack can be determined, and the contact pressure can be adjusted accordingly. Then the screed height can be determined again and the position of the traction point adjusted. This iterative process can be repeated.

[0042] The adjustment of the position (particularly the height) of the traction point can be carried out during operation of the road paver, in particular during installation of the paving material. The adjustment of the contact pressure can be carried out during operation of the road paver, in particular during installation of the paving material. The adjustment of the position (particularly the height) of the traction point and the adjustment of the contact pressure can take place during operation of the road paver, in particular during installation of the paving material. During installation of the paving material, the road paver moves in the paving direction.

[0043] The adjustment of the position, in particular the height, of the traction point can be carried out automatically, in particular by means of a feedback control device or a control device. The adjustment of the contact pressure can be carried out automatically, in particular by means of a feedback control device or a control device. The adjustment of the position, in particular the height, of the traction point and the adjustment of the control device can be carried out automatically, in particular by means of a feedback control device or a control device.

[0044] The determined screeding height may be fed to a feedback control device or a control device. The determined angle of attack may be fed to a feedback control device or a control device. The determined screeding height and the determined angle of attack may be fed to a feedback control device or a control device.

[0045] The feedback control device may have a general multivariable controller for feedback controlling the ironing height and the angle of attack. The multivariable controller may be an H-infinity controller, an LQ controller (linear quadratic controller) or an LQG controller.

[0046] The feedback control device may have two independent controllers. The feedback control device may have a first controller for feedback controlling the screed height. The feedback control device may have a second controller for feedback controlling the angle of attack.

[0047] The position (particularly the height) of the traction point can also be adjusted according to the determined angle of attack. In addition, the contact pressure of the screed assembly can also be adjusted according to the determined screed height.

[0048] The position, in particular the height, of the towing point can be adjusted by means of a levelling cylinder, in particular two levelling cylinders. The levelling cylinder can be attached to the towing vehicle and the towing point of the road paver. The position of the towing point can be changed by extending or retracting the levelling cylinder. The screed assembly can be attached to the towing point by means of a towing arm, in particular two towing arms. Thus, by extending or retracting the levelling cylinder or the levelling cylinders, the screed height of the screed assembly can be changed.

[0049] The contact pressure of the screed assembly can be adjusted by means of screed lift cylinders, in particular two screed lift cylinders. The screed lift cylinders can be attached to the screed assembly and to the tractor of the road paver. The pressure on the screed assembly can be varied by extending and retracting the screed lift cylinders. A pressure control valve can be used to adjust, in particular to regulate, the pressure in the screed lift cylinders. The screed lift cylinders can have a rod side and a piston side. The pressure control valve can be used to adjust, in particular to regulate, the pressure on the rod side of the screed lift cylinders. The screed lift cylinders can be used to vary the pressure on the screed assembly. The pressure control valve can be used to vary the pressure on the screed assembly. The screed lift cylinders can be adapted to release the screed assembly and / or to additionally load the screed assembly. The angle of attack of the screed assembly can be adjusted by extending and retracting one screed lift cylinder or a plurality of screed lift cylinders. A higher contact pressure results in a larger angle of attack. A lower contact pressure results in a smaller angle of attack.

[0050] The screed lift cylinder can have a pressure control mechanism on the piston side. The pressure control mechanism on the piston side can be used to increase the angle of attack.

[0051] A third aspect of the invention relates to feedback controlling the angle of attack of a screed assembly of a road paver and feedback controlling the screed height of the screed assembly using a feedback control device.

[0052] The feedback control means may be adapted to feedback control the angle of attack and the screed height during operation of the road paver, in particular during installation of the paving material. The feedback control may occur automatically. The feedback control may occur continuously. The feedback control may occur periodically.

[0053] The feedback control device may be adapted to receive and process measurements from the first measuring device for determining the screed height and measurements from the second measuring device for determining the angle of attack. The feedback control device may perform feedback control based on the transmitted measurements of screed height and angle of attack.

[0054] The feedback control device may be adapted to control a leveling cylinder, in particular two leveling cylinders. The leveling cylinders may change the position, in particular the height, of a towing arm connected to the screed assembly. The feedback control device may be adapted to change the screed height by controlling the leveling cylinders.

[0055] The feedback control device may be adapted to control a screed lift cylinder, in particular two screed lift cylinders. The screed lift cylinders change the contact pressure of the screed assembly on the paving material. The contact pressure may be used to adjust the angle of attack of the screed assembly. The feedback control device may be adapted to change the contact pressure of the screed assembly by controlling a screed lift cylinder, in particular a plurality of screed lift cylinders. The feedback control device may be adapted to change the angle of attack of the screed assembly by controlling a screed lift cylinder, in particular a plurality of screed lift cylinders.

[0056] The feedback control device may have a multivariable controller. The multivariable controller may be used for feedback control of the angle of attack of the screed assembly and for feedback control of the screed height of the screed assembly. The multivariable controller may be adapted to use the determined angle of attack and the determined screed height as input parameters. The multivariable controller may be adapted to control a leveling cylinder (in particular a plurality of leveling cylinders) and a screed lifting cylinder (in particular a plurality of screed lifting cylinders), in particular based on the determined screed height and the determined angle of attack.

[0057] The feedback control device may have a first controller and a second controller. The first controller may be used for feedback control of the screed height of the screed assembly. The second controller may be used for feedback control of the angle of attack of the screed assembly. The first controller may be used for controlling a leveling cylinder (in particular, a plurality of leveling cylinders). The second controller may be used for controlling a screed lifting cylinder (in particular, a plurality of screed lifting cylinders).

[0058] The road paver according to the first aspect of the invention may be used together with the method steps of the method according to the second aspect of the invention. The method according to the second aspect of the invention may be performed using the road paver according to the first aspect of the invention. The use of the feedback control device according to the third aspect of the invention may be performed by the road paver according to the first aspect of the invention and / or using the method steps of the method according to the second aspect of the invention.

[0059] The expressions "first", "second", "third" and "fourth" should be understood as definitions of specific elements or components only, and do not necessarily imply a specific order of the components or components. For example, the presence of the second component does not necessarily mean the presence of the first component, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The present invention is described in more detail below with reference to the embodiments.

[0061] Figure 1 A schematic side view of a road paver with a screed assembly according to an embodiment of the present invention is shown.

[0062] Figure 2 A schematic top view of a road paver with a screed assembly according to an embodiment of the present invention is shown.

[0063] Figure 3 A schematic side view of a screed assembly and a trailing arm in a first installation position is shown according to an embodiment of the present invention.

[0064] Figure 4 A schematic side view of a screed assembly and a trailing arm in a second installation position is shown according to an embodiment of the invention.

[0065] Figure 5A schematic side view of a screed assembly and a trailing arm in a third installation position is shown according to an embodiment of the present invention.

[0066] FIG. 6 shows a feedback control circuit known in the prior art for feedback controlling the position of a screed assembly.

[0067] Figure 7 A feedback control circuit for feedback controlling the position of a screed assembly according to an exemplary embodiment of the present invention is shown.

[0068] Figure 8 A feedback control circuit for feedback controlling the position of a screed assembly according to an exemplary embodiment of the present invention is shown.

[0069] Fig. 9 A feedback control circuit for feedback controlling the position of a screed assembly according to an exemplary embodiment of the present invention is shown. DETAILED DESCRIPTION

[0070] Figure 1 A road paver 1 according to an embodiment of the invention is shown. The road paver 1 comprises a tractor 2 and a screed assembly 3. The screed assembly 3 is connected to the tractor 2 by means of two traction arms 4, each of which extends laterally on the road paver 1. The traction arms 4 are pivotably connected to the tractor 2 at a traction point 5. The screed assembly 3 is arranged behind the tractor 2 with respect to the paving direction 100 and is towed behind the tractor 2 by the traction 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 tractor 2 against the paving direction 100 and is delivered to the screed assembly 3. A lateral distribution device 7 can be provided in the rear area of ​​the tractor 2, which distributes the paving material orthogonally to the paving direction 100 to the front of the screed assembly 3.

[0071] A leveling cylinder 8 is arranged on each side of the road paver 1. The leveling cylinder 8 is connected to the respective towing arm 4 via an intermediate piece 9. The position (in particular the height) of the towing point 5 can be adjusted by means of the leveling cylinder 8. The screed lift cylinder 10 is arranged in the rear area of ​​the road paver 2. The screed lift cylinder 10 is attached to the rear area of ​​the respective towing arm 4. Alternatively, the screed lift cylinder 10 can also be directly connected to the screed assembly 3. The screed lift cylinder 10 can be used to adjust the position (in particular the height and the contact pressure) of the screed assembly 3.

[0072] Figure 2A top view of a road paver 1 according to an embodiment of the invention is shown. A towing arm 4 is arranged on the side of the towing vehicle 2. The screed assembly 3 comprises a bottom screed plate 11 and two extensions 12. The extensions 12 are arranged behind the bottom screed plate 11 in the paving direction 100. Alternatively, the extensions 12 can be arranged in front of the bottom screed plate 11 in the paving direction 100. The extensions 12 are arranged laterally adjacent to the bottom screed plate 11 in the transverse direction 200. The extensions 12 can 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. By equipping the extensions with widening portions, the width of the screed assembly can be increased.

[0073] Figure 3 A schematic side view of the screed assembly 3 and the towing arm 4 is shown in a first installation situation on a flat roadbed 13. The extension 12 is arranged behind the bottom screed plate 11 in the paving direction 100. The extension 12 has the same angle of attack 14 as the bottom screed plate 11. The dashed line indicates the desired installation height 15 of the finished paving material. The bottom screed plate 11 and the extension 12 are arranged offset in the vertical direction. The vertical offset 16 between the bottom screed plate 11 and the extension 12 is adjusted so that the extension height 18 corresponds to the bottom screed plate height 17. This is usually adjusted manually before installation.

[0074] Figure 4 The screed assembly 3 and the trailing arm 4 are shown in a second installation situation. Figure 3 Compared to the traction point 5, the traction point 5 is higher. This results in a larger angle of attack 14. The angle of attack 14 of the bottom screed 11 and the extension 12 remains the same. Figure 4 It can be seen that the bottom screed height 17 corresponds to the desired installation height 15. Since the extension 12 is arranged behind the bottom screed plate 11 in the paving direction 100, the rear edge of the extension 12 is sunken deeper than the rear edge of the bottom screed plate 11. Therefore, the extension height 18 is smaller than the bottom screed height 17. This results in the finished paving material being non-uniform in the transverse direction.

[0075] Figure 5 The screed assembly 3 and the towing arm 4 are shown in a third installation situation. The roadbed 13 has a roadbed inclination 19 . Figure 5 Only the bottom screed plate 11 is shown. The leveling cylinder 8 is attached to the front area of ​​the towing arm 4 for adjusting the position of the towing point 5. The screed plate lifting cylinder 10 is attached to the rear area of ​​the towing arm 4 for adjusting the contact pressure of the screed plate assembly 3 with the paving material. Figure 5In the position of the screed assembly 3 shown, the bottom screed height 17 corresponds to the desired installation height 15. The bottom screed 11 has an absolute bottom screed inclination 20. The absolute bottom screed inclination 20 is the inclination of the bottom screed 11 relative to the horizontal. The angle of attack 14 of the bottom screed 11 is calculated by subtracting the roadbed inclination 19 from the absolute bottom screed inclination 20.

[0076] FIG6 shows a feedback control circuit known from the prior art, which has a feedback control device 50 for feedback controlling the position of the screed assembly 3. The screed conveying behavior 51 is influenced by the screed lift cylinder pressure 52, the roadbed height 53 and the leveling cylinder position 54. The screed lift cylinder pressure 52 and the roadbed height 53 are external input parameters. Another input parameter is the desired installation height 15. The screed height 55 and the angle of attack 14 are determined from the screed lift cylinder pressure 52, the roadbed 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, changes the leveling cylinder position 54. The controller 57 only reacts to changes in the screed height 55. The controller 57 does not react to changes in the angle of attack 14.

[0077] Figure 7 A control circuit according to an exemplary embodiment of the invention is shown, which has a feedback control device 50 for feedback controlling the position of the screed assembly 3. As shown in FIG6 , the screed conveying behavior 51 is influenced by the screed lifting cylinder pressure 52, the roadbed height 53 and the leveling cylinder position 54. Compared with the control circuit shown in FIG6 , only the roadbed height 53 is an external input parameter. The desired installation height 15 and the desired angle of attack 58 are specified as target values. The target value of the installation height 15 and / or the target value of the angle of attack 58 can be specified by manual input by the user. The target value of the installation height 15 and / or the target value of the angle of attack 58 can be specified or suggested by the control system (in particular, depending on the paving material). The target value of the installation height 15 and / or the target value of the angle of attack 58 can be determined based on values ​​stored from previous construction measurements. The screed height 55 and the angle of attack 14 of the screed assembly 3 are adjusted according to the screed lifting cylinder pressure 52, the roadbed 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, changes the leveling cylinder position 54. The angle of attack 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 angle of attack 58 with the measured angle of attack 14 and, if necessary, changes the screed lift cylinder pressure 52. The first controller 60 responds to changes in the screed height 55, while the second controller 62 responds to changes in the angle of attack 14.

[0078] Figure 8 1 shows a control circuit according to another exemplary embodiment of the present invention, which has a feedback control device 50 for feedback controlling the position of the screed assembly 3. Figure 7 Compared with the control circuit shown, Figure 8 The control circuit in 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 a first controller 60 and a second controller 62. The first controller 60 compares the desired installation height 15 with the measured screed height 55 and, if necessary, changes the leveling cylinder position 54. The second controller 62 compares the desired installation height 15 with the measured screed height 55 and, if necessary, changes the screed lift cylinder pressure 52.

[0079] Fig. 9 1 shows a control circuit according to another exemplary embodiment of the present invention, which has a feedback control device 50 for feedback controlling the position of the screed assembly 3. Figure 7 Compared with the control circuit shown, Fig. 9 The control circuit in has a multivariable controller 63. The first measuring device 59 measures the screed height 55 of the screed assembly 3 and transmits it to the multivariable controller 63. The second measuring device 61 measures the angle of attack 14 of the screed assembly 3 and transmits it to the multivariable controller 63. The multivariable controller 63 compares the desired installation height 15 with the measured screed height 55 and uses the comparison to calculate the control deviation of the screed height. The multivariable controller 63 compares the desired angle of attack 58 with the measured angle of attack 14 and uses the comparison to calculate the control deviation of the angle of attack. Based on the control deviation of the screed height and the control deviation of the angle of attack, the multivariable controller 63 changes the screed lifting cylinder pressure 52 and the leveling cylinder position 54 when necessary. The multivariable controller 63 can be a MIMO controller (multiple-input multiple-output controller).

Claims

1. A road paver (1), comprising: Tractor (2), at least one traction arm (4), a screed assembly (3) attached to a towing point (5) of the towing vehicle (2) via at least one towing arm (4), and a leveling cylinder (8) adapted to adjust the position of the traction point (5), a screed lifting cylinder (10) adapted to adjust the contact pressure of the screed assembly (3), a first measuring device (59) adapted to determine the screed height (55) of the screed assembly (3), a second measuring device (61) adapted to determine the angle of attack (14) of the screed assembly (3), and A feedback control device (50) is provided, which is suitable for controlling the levelling cylinder (8) and the screed lifting cylinder (10).

2. The road paver according to claim 1, wherein: The leveling bar (8) is suitable for adjusting the height of the traction point (5).

3. The road paver according to claim 1, wherein: The feedback control device (50) comprises a first controller (60) and a second controller (62), wherein the first controller (60) is adapted to control the leveling cylinder (8) based on a control deviation of the screed height (55), and the second controller (62) is adapted to control the screed lifting cylinder (10) based on a control deviation of the attack angle (14).

4. The road paver according to claim 1, wherein: The feedback control device (50) comprises a first controller (60) and a second controller (62), wherein the first controller (60) is adapted to control the leveling cylinder (8) based on a control deviation of the ironing height (55), and the second controller (62) is adapted to control the ironing plate lifting cylinder (10) based on the control deviation of the ironing height (55).

5. The road paver according to claim 1, wherein: The feedback control device (55) has a multivariable controller (63) adapted to control the leveling cylinder (8) and the screed lifting cylinder (10) based on a control deviation of the screed height (55) and a control deviation of the attack angle (14).

6. The road paver according to any one of claims 1 to 5, wherein: The second measuring device (61) has a first inclination sensor arranged on the screed assembly (3) and a second inclination sensor arranged on the tractor (2), wherein the first inclination sensor is adapted to determine an inclination angle of the screed assembly (3) relative to a horizontal plane, wherein the second inclination sensor is adapted to determine the inclination angle of the tractor (2) relative to a horizontal plane, The second measuring device is suitable for determining the angle of attack (14) of the screed assembly (3) based on the inclination angle of the screed assembly (3) and the inclination angle of the tractor (2).

7. The road paver according to any one of claims 1 to 5, wherein: The second measuring device (61) has a rotation angle sensor which is arranged at the towing point (5) of the towing vehicle (2).

8. The road paver according to any one of claims 1 to 5, wherein: The screed assembly (3) comprises a bottom screed (11) and at least one extension (12), wherein the extension (12) is arranged at least partially offset from the bottom screed (11) in a paving direction (100) of the road paver (1), and wherein the bottom screed (11) and the extension (12) have the same angle of attack (14).

9. A method for feedback controlling the position of a screed assembly (3) attached to a towing point (5) of a road paver (1), comprising: determining the ironing height (55) of the ironing screed assembly (3), determining an angle of attack (14) of the screed assembly (3), The position of the pulling point (5) is adjusted according to the determined ironing height (55). The contact pressure of the ironing plate assembly (3) is adjusted according to the determined angle of attack (14).

10. The method according to claim 9, wherein: Adjusting the position of the traction point (5) according to the determined screed height (55) means adjusting the height of the traction point (55) according to the determined screed height (55).

11. The method according to claim 9, wherein: The position of the traction point (5) is adjusted during operation of the road paver (1), and the contact pressure is adjusted.

12. The method according to any one of claims 9 to 11, wherein: Adjusting the position of the pulling point (5) and adjusting the contact pressure are performed automatically.

13. The method according to claim 12, wherein: The position of the pulling point (5) and the contact pressure are adjusted automatically by a feedback control device (50).

14. The method according to any one of claims 9 to 11, wherein: The determined screed height (55) and the determined angle of attack (14) are fed to a feedback control device (50) of a road paver (1), wherein the feedback control device (50) has a multivariable controller (63) or two separate controllers (60, 61) for controlling the screed height (55) and controlling the angle of attack (14).

15. The method according to any one of claims 9 to 11, wherein: The position of the traction point (5) is adjusted based on the determined angle of attack (14), and the contact pressure of the screed assembly (3) is adjusted based on the determined screed height (55).

16. The method according to any one of claims 9 to 11, wherein: The position of the traction point (5) is adjusted by means of a leveling cylinder (8), and the contact pressure of the screed assembly (3) is adjusted by means of a screed lifting cylinder (10).

17. Use of a feedback control device (50) for feedback control of an angle of attack (14) of a screed assembly (3) of a road paver (1) and for feedback control of a screed height (55) of the screed assembly (3).

18. Use of the feedback control device according to claim 17, wherein: The feedback control device (50) has a multivariable controller (63), and the multivariable controller (63) is used for feedback controlling the angle of attack (14) of the screed assembly (3) and feedback controlling the ironing height (55) of the screed assembly (3); or, the feedback control device (50) has a first controller (60) and a second controller (62), wherein the first controller (60) is used for feedback controlling the ironing height (55) of the screed assembly (3), and the second controller (62) is used for feedback controlling the angle of attack (14) of the screed assembly (3).

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