Road paver with a screed levelling control

Abstract

The invention relates to a road paver (1) comprising a towing vehicle (2), at least one drawbar (4), a screed assembly (3) which is attached to a towing point (5) of the towing vehicle (2) via the at least one drawbar (4), a leveling cylinder (8) which is configured to adjust a position, in particular a height, of the towing point (5), a screed lifting cylinder (10) which is configured to adjust a contact pressure of the screed assembly (3), a first measuring device (59) which is configured to determine a screed height (55) of the screed assembly (3), a second measuring device (61) which is configured to determine an angle of attack (14) of the screed assembly (3), and a control device (50) which is configured to control the leveling cylinder (8) and the screed lifting cylinder (10).The invention further relates to a method for controlling the position of a plank assembly (3) and the use of a control device (50) for controlling an angle of attack (14) and a plank height (55) of a plank assembly (3).

Description

[0001] The present invention relates to the technical field of road pavers. In particular, the invention relates to road pavers with a screed for compacting paving material, as well as methods for controlling such road pavers.

[0002] DE 10 2021 107 447 A1 discloses a method for determining a change in the angle of attack of a paving screed. DE 19 647 150 A1 discloses a method for controlling the screed height of a paving screed. EP 2 366 831 B1 discloses a method for controlling the paving thickness and quality of bituminous paving material.

[0003] In state-of-the-art leveling controls, the screed height of the paving screed is recorded and adjusted using a leveling cylinder. During paving, a screed lifting cylinder is typically in the floating position. To influence static compaction, a constant pressure can be set on the rod side of the screed lifting cylinder. The underside of the paving screed is inclined relative to the subsoil. This inclination is referred to as the angle of attack and is initially set to a predefined value, partly by the screed lifting cylinder. The angle of attack influences the quality of the paving result, in particular the compaction of the paving material and the resulting surface appearance. A constant angle of attack during operation is therefore advantageous.

[0004] A change in the screed height, a change in the paving speed of the road paver, and / or a change in the paving material can cause a change in the screed's angle of attack. An angle of attack that is too large or too small can lead to poor paving results. Especially in pavers with extending screeds, an undesirable angle of attack can lead to differences in the screed height between the base screed and the extending sections, resulting in unevenness across the road.

[0005] In the current systems, only the screed height is continuously adjusted by adjusting the leveling cylinder. However, this means that the angle of attack is not constant, but rather depends on the current position of the leveling cylinder, the properties of the paving material, and other environmental conditions. The angle of attack is geometrically defined by the position of the leveling cylinder and the layer thickness.

[0006] The aim of the present invention is to keep the angle of attack of the screed as constant as possible during operation and thus to improve the paving quality.

[0007] This object is achieved by a road finisher according to claim 1, a method for controlling a position of a screed arrangement according to claim 8 or a use of a control device according to claim 14.

[0008] The present invention can significantly improve the paving result. Continuous monitoring and adjustment of the screed angle of attack allows the longitudinal evenness of the paved material to be improved. When using extending screeds, the present invention can also improve the transverse evenness of the paved material. Furthermore, the compaction result can be improved by maintaining a constant angle of attack. Process reliability can also be increased with the present invention, as manual monitoring and manual readjustment of the angle of attack are no longer necessary. The system can automatically react to changes in the paving material, thereby reducing paving errors.

[0009] A first aspect of the invention relates to a road paver comprising a towing vehicle, at least one drawbar, a screed assembly, a leveling cylinder, a screed lifting cylinder, a first measuring device, a second measuring device, and a control device. The screed assembly is attached to a towing point of the towing vehicle via the at least one drawbar. The leveling cylinder is designed to adjust a position, in particular the height, of the towing point. The screed lifting cylinder is designed to adjust a contact pressure of the screed assembly. The contact pressure refers to the pressure that the screed assembly exerts on the paving material, in particular due to its own weight. The contact pressure of the screed assembly can result from the dead weight of the screed assembly and the forces from the screed lifting cylinder. The forces from the screed lifting cylinder can have a loading or relieving effect.The first measuring device is designed to determine a screed height of the screed assembly. The second measuring device is designed to determine an angle of attack of the screed assembly. The control device is designed to control the leveling cylinder and the screed lifting cylinder.

[0010] The screed assembly can be configured to form a road paver together with a towing vehicle. The screed assembly can be attached to the towing vehicle. The screed assembly can be configured to be pulled behind the towing vehicle in the paving direction of travel. The screed assembly can be configured to compact paving material, in particular bituminous paving material, on a subgrade. The screed assembly can be configured to smooth paving material, in particular bituminous paving material, on a subgrade.

[0011] A 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. A lateral direction or width direction can be a direction parallel to the transverse direction.

[0012] The paving screed assembly can comprise a base screed and at least one extending part, preferably two extending parts. The base screed is also referred to as the main screed in the context of the invention. The extending part is also referred to as the secondary screed in the context of the invention. The extending parts can be arranged laterally, transversely, to the left and right of the base screed. The extending parts can be arranged behind the base screed in the paving direction. Alternatively, the extending parts can be arranged in front of the base screed in the paving direction.

[0013] The base screed may comprise a base screed screed plate for contacting the paving material. The extendable part may comprise a screed plate support and an extendable part screed plate. The extendable part screed plate may be configured for contacting the paving material. The extendable part screed plate may be attached to the screed plate support so as to be tiltable about a tilt axis. The screed assembly may comprise a height adjustment device. The screed assembly may comprise a tilting device. The height adjustment device may be designed to lower or raise the extendable part or parts relative to the base screed. The height adjustment device may be configured to lower or raise the screed plate support relative to the base screed. The tilting device may be configured to change a tilt angle of the extendable part screed plate about the tilt axis. The tilt axis may extend in the transverse direction. The tilt axis may extend horizontally.

[0014] The screed height of the screed arrangement can refer to the vertical distance between a rear edge of the screed arrangement, in particular a rear edge of a screed plate of the screed arrangement, and a reference point, for example on the subsoil. The screed height of the base screed can refer to the vertical distance between a rear edge of the base screed, in particular a rear edge of the base screed screed, and a reference point, for example on the subsoil. The screed height of the extending part can refer to the vertical distance between a rear edge of the extending part, in particular a rear edge of the extending part screed, and a reference point, for example on the subsoil. The term rear edge refers to the rearmost edge of the base screed or the extending part in the paving direction. The height of the rear edge or the screed height determines the paving height of the paving material.

[0015] The angle of attack of the screed assembly can refer to the inclination of the screed assembly, in particular a screed plate of the screed assembly, relative to the subgrade slope. For a horizontal subgrade, the angle of attack of the screed assembly corresponds to the absolute inclination of the screed plate. The term "absolute inclination" indicates that the inclination is determined relative to a horizontal plane. For a sloped subgrade, the angle of attack corresponds to the difference between the absolute inclination of the screed plate and the absolute inclination of the subgrade.

[0016] The angle of attack of the base screed can refer to the inclination of the base screed, in particular of the base screed screed plate, relative to the subgrade slope. The angle of attack of the extendable part can refer to the inclination of the extendable part, in particular of the extendable part screed plate, relative to the subgrade slope.

[0017] The screed assembly can be rotatably attached to a towing point of the road paver, in particular a towing vehicle of the road paver, via at least one towing bar. The screed assembly can be rotatably attached to the towing point of the road paver, in particular the towing vehicle, via two towing bars. The towing bars can be arranged laterally on the towing vehicle. A towing bar can be arranged on each side of the towing vehicle. The height of the towing point can be adjusted using a leveling cylinder. The road paver can have two towing bars and two leveling cylinders. Each leveling cylinder can be assigned to a towing bar. The leveling cylinders can be connected to the respective towing bar. The connection between the leveling cylinder and the towing bar can be made directly or via an intermediate piece. The leveling cylinders and the towing bars can be arranged laterally on the road paver with respect to the transverse direction.The road paver can have a drawbar and a leveling cylinder on each side. The features described in the remainder of this application in connection with the leveling cylinder also apply to both leveling cylinders, even if this is not explicitly stated.

[0018] The screed assembly, in particular the base screed, can be connected to the towing vehicle by a screed lifting cylinder. The screed assembly, in particular the base screed, can be connected to the towing vehicle by two screed lifting cylinders. The screed lifting cylinder(s) can be used to raise or lower the screed assembly vertically. The screed lifting cylinder(s) can be used to adjust the contact pressure of the screed assembly to the paving material. The features described below in connection with the screed lifting cylinder also apply to both screed lifting cylinders, even if this is not explicitly mentioned.

[0019] The screed lift cylinder can be connected directly to the screed assembly or base screed. The screed lift cylinder can be connected indirectly to the screed assembly or base screed. The screed lift cylinder can be attached to the drawbar, particularly to a rear area of ​​the drawbar.

[0020] The road paver may have a material hopper. The material hopper may be designed to hold paving material. The material hopper may be located in front of the screed assembly in the direction of paving travel.

[0021] The road paver may have a control device. The control device may be configured to control the screed lifting cylinder. The control device may be configured to control the leveling cylinder. The control device may be configured to control the screed lifting cylinder and the leveling cylinder. The control device may be part of the control system.

[0022] The control device can have a first controller. The first controller can be designed to control the leveling cylinder or 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 the desired paving height, and the actual value of the screed height. The control deviation of the screed height can be determined from 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 can be specified by manual user input. The target value of the screed height can be specified or suggested by a control system, in particular depending on the paving material. The target value of the screed height can be determined based on stored values ​​from previous construction projects. The target value of the screed height can be derived from the road construction plan.The target screed height can be entered manually. The target value can be imported directly from digital planning data.

[0023] The control device can have a second controller. The second controller can be designed to control the screed lifting cylinder(s) 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, for example the desired angle of attack, and the actual value of the angle of attack. The control deviation of the angle of attack can be determined from the target value of the angle of attack and the actual angle of attack determined by the second measuring device. The second controller can be designed to calculate the required pressure in the screed lifting cylinder based on the determined actual angle of attack. The target value of the angle of attack can be specified by manual user input. The target value of the angle of attack can be specified or suggested by a control system, in particular depending on the paving material.The target angle of attack can be determined based on stored values ​​from previous construction projects. The target angle of attack can be selected to match the height setting of the extension section. This allows for good compaction, which can lead to a good paving pattern.

[0024] The control device may comprise a first controller. The first controller may be configured to control the leveling cylinder based on a control deviation of the screed height. The control device may comprise a second controller. The second controller may be configured to control the screed lifting cylinder based on a control deviation of the screed height.

[0025] The first controller can be a SISO controller (single-input-single-output controller), for example, a P controller (proportional controller), a PI controller (proportional-integral controller), or a PID controller (proportional-integral-derivative controller). The first controller can be a robust controller, for example, an H-infinity controller. The second controller can be a SISO controller, for example, a P controller, a PI controller, or a PID controller. The second controller can be a robust controller, for example, an H-infinity controller.

[0026] The control device can comprise a multivariable controller. The multivariable controller can be configured 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 controlled variables, angle of attack and screed height, can be controlled by one controller, the multivariable controller. This allows interactions between the two controlled variables, angle of attack and screed height, and the two manipulated variables, leveling cylinder and screed lifting cylinder, to be taken into account. The multivariable controller can also be referred to as a MIMO controller (multiple input multiple output controller). The multivariable controller can be an H-infinity controller, an LQ controller, or an LQG controller.

[0027] In systems known from the prior art, the current paving speed is generally included in the control. With the control device according to the invention, this is not necessary. The control device, in particular the multi-variable controller, can be designed not to output any further manipulated variables other than the angle of attack and the screed height. The control device, in particular the multi-variable controller, can be designed to control the screed lifting cylinder and the leveling cylinder based exclusively on the angle of attack and the screed height, in particular on a target-actual comparison of the angle of attack and a target-actual comparison of the screed height. The control device, in particular the multi-variable controller, can be designed to control the screed lifting cylinder and the leveling cylinder based exclusively on measured values ​​from the first measuring device and the second measuring device.The control device, in particular the multi-variable controller, can be designed to control the screed lifting cylinder and the leveling cylinder without taking the paving speed into account. The control device can be designed to select control parameters depending on the paving speed. The control device can be designed to control the screed lifting cylinder and the leveling cylinder depending on the paving speed. The control device can be designed to apply a large controller gain at a high paving speed and a small controller gain at a low paving speed. The terms "high," "low," "large," and "small" are to be understood in relation to one another.

[0028] The first measuring device can be a distance meter, for example a laser distance meter, a mechanical probe or an acoustic distance meter.

[0029] The second measuring device may include a first inclination sensor. The second measuring device may include a second inclination sensor. The second measuring device may include the first inclination sensor and the second inclination sensor. The first inclination sensor may be arranged on the screed assembly. The second inclination sensor may be arranged on the towing vehicle.

[0030] The first inclination sensor can be configured to determine an inclination angle of the screed assembly relative to a horizontal plane. The second inclination sensor can be configured to determine an inclination angle of the towing vehicle relative to the horizontal plane. The second measuring device can be configured to determine the angle of attack of the screed assembly from the inclination angle of the screed assembly and the inclination angle of the towing vehicle.

[0031] The first inclination sensor can be designed to determine an inclination angle of the base screed relative to a horizontal plane. The first inclination sensor can be designed to determine an inclination angle of the extendable part relative to a horizontal plane. The inclination angle of the towing vehicle can correspond to the inclination of the ground. Alternatively, the inclination of the ground or the inclination angle of the towing vehicle can be determined from a digital terrain model. The second inclination sensor on the towing vehicle is not necessary in this case. The angle of attack can be calculated based on the measured inclination angle of the first inclination sensor and the inclination of the ground determined from the terrain model. Several first inclination sensors can be attached so that the inclination angle of the screed arrangement is determined and controlled at several points, for example on two extendable parts.Several second inclination sensors can be installed so that the inclination angle of the towing vehicle is determined from the average value of the second inclination sensors.

[0032] The second measuring device can comprise an inclination sensor attached to the base screed or the extending part. The inclination sensor can be configured to determine an inclination angle of the base screed or the extending part relative to a horizontal plane. A control unit of the road paver can be configured to determine a subgrade inclination based on a digital terrain model. The control unit can be configured to determine the angle of attack of the base screed based on the determined inclination angle of the base screed and the subgrade inclination. The control unit can be configured to determine the angle of attack of the extending part based on the determined inclination angle of the extending part and the subgrade inclination.

[0033] The second measuring device can comprise a rotation angle sensor. The rotation angle sensor can be arranged at the towing point of the towing vehicle. The rotation angle sensor can be designed to measure the inclination of the drawbar relative to the inclination of the towing vehicle. The screed assembly can be rigidly connected to the drawbar. The inclination of the drawbar can then be used to determine the angle of attack of the screed assembly. The rotation angle measured at the towing point can correspond to the angle of attack.

[0034] The second measuring device can comprise a first rotation angle sensor on a first drawbar mounted on the side of the towing vehicle and a second rotation angle sensor on a second drawbar mounted on the other side of the towing vehicle. The angle of attack of the screed assembly can then be determined based on the average value of the first and second rotation angle sensors.

[0035] The closed-loop control device and / or the control device can be configured to filter environmental influences. The closed-loop control device and / or the control device can be configured to filter influences from vibration and / or temperature fluctuations. Advanced signal processing methods, such as Kalman filters or state observers, can be used for this purpose.

[0036] The screed assembly can have a base screed and at least one extending part. The extending part can be arranged at least partially offset from the base screed in the paving direction of the road paver. The extending part can be arranged at least partially in front of or behind the base screed in the paving direction of the road paver. The extending part can be arranged completely in front of or behind the base screed in the paving direction of the road paver. The base screed and the extending part can have the same angle of attack. The extending part can be arranged laterally, relative to the transverse direction, next to the base screed. The screed assembly can have two extending parts. The extending parts can be arranged on both sides, relative to the transverse direction, of the base screed. The extending parts can be extendable and retractable laterally so that the width of the screed assembly can be varied.The width of the screed assembly corresponds to the transverse extension of the screed assembly. The extending section can have a vertical offset relative to the base screed. The vertical offset can be adjusted using the height adjustment device. Due to the geometric arrangement of the base screed and extending section, the vertical offset is only optimal for a specific angle of attack. If the angle of attack changes, the vertical offset must be adjusted. Otherwise, the base screed and the extending section have different screed heights. This can lead to the extending section leaving marks in the paved layer and unevenness in the transverse direction. The screed assembly can also consist of just a base screed and no extending sections.

[0037] The screed lift cylinder can have a pressure control device on the piston side. The screed lift cylinder can be designed to allow for the unloading and loading of the screed assembly. This allows for correction of both excessive and excessive angles of attack. The control device can adjust the angle of attack for both excessive and excessive angles of attack.

[0038] A second aspect of the invention relates to a method for controlling the position of a screed assembly of a road paver. The screed assembly is attached to a traction point of the road paver, in particular by means of at least one drawbar. 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 traction point based on the determined screed height. The method further comprises adjusting a contact pressure of the screed assembly based on the determined angle of attack.

[0039] Adjusting the position of the pull point may include adjusting the height, a vertical position, of the pull point.

[0040] The screed height can be determined continuously. The screed angle can be determined continuously. The screed height can be determined simultaneously with the screed angle. The screed height and / or the screed angle can be determined at regular intervals.

[0041] The position of the traction point can be adjusted continuously. The contact pressure can be adjusted continuously. The position of the traction point can be adjusted simultaneously with the contact pressure. The position of the traction point and / or the contact pressure can be adjusted at regular intervals.

[0042] The position of the traction point can be adjusted at a time staggered from the adjustment of the contact pressure. For example, the screed height can first be determined, and the position of the traction point can be adjusted based on this. The angle of attack can then be determined, and the contact pressure can be adjusted based on this. The screed height can then be determined again, and the position of the traction point can be adjusted. This iterative process can be repeated continuously.

[0043] The position, in particular the height, of the traction point can be adjusted while the road paver is operating, particularly during the paving of the paving material. The contact pressure can be adjusted while the road paver is operating, particularly during the paving of the paving material. The position, in particular the height, of the traction point and the contact pressure can be adjusted while the road paver is operating, particularly during the paving of the paving material. The road paver moves in the paving direction of travel while the paving material is being paved.

[0044] The adjustment of the position, in particular the height, of the traction point can be carried out automatically, in particular by a regulating or control device. The adjustment of the contact pressure can be carried out automatically, in particular by a regulating or 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 a regulating or control device.

[0045] The determined screed height can be fed to a control or regulation device. The determined angle of attack can be fed to a control or regulation device. The determined screed height and the determined angle of attack can be fed to a control or regulation device.

[0046] The control system can comprise a common multivariable controller for controlling the screed height and the angle of attack. The multivariable controller can be an H-infinity controller, an LQ controller (linear quadratic controller), or an LQG controller.

[0047] The control device may have two separate controllers. The control device may have a first controller for controlling the screed height. The control device may have a second controller for controlling the angle of attack.

[0048] Adjusting the position, especially the height, of the traction point can also be based on the determined angle of attack. Adjusting the contact pressure of the screed arrangement can also be based on the determined screed height.

[0049] The position, in particular the height, of the traction point can be adjusted using a leveling cylinder, in particular two leveling cylinders. The leveling cylinder can be attached to the road paver's towing vehicle and to the traction point. The position of the traction point can be changed by extending and retracting the leveling cylinder. The screed assembly can be attached to the traction point using a drawbar, in particular two drawbars. The screed height of the screed assembly can thus be changed by extending and retracting the leveling cylinder(s).

[0050] The contact pressure of the screed assembly can be adjusted using a screed lifting cylinder, in particular two screed lifting cylinders. The screed lifting cylinder can be attached to the screed assembly and to the towing vehicle of the road paver. The pressure on the screed assembly can be varied by extending and retracting the screed lifting cylinder. A pressure in the screed lifting cylinder can be set, in particular regulated, using a pressure regulating valve. The screed lifting cylinder can have a rod side and a piston side. The pressure on the rod side of the screed lifting cylinder can be set, in particular regulated, using the pressure regulating valve. The pressure on the screed assembly can be varied by the screed lifting cylinder. The pressure on the screed assembly can be varied by the pressure regulating valve. The screed lifting cylinder can be designed to relieve the load on the screed assembly and / or apply additional load.By extending and retracting the screed lift cylinder(s), the angle of attack of the screed assembly can be adjusted. A higher contact pressure can result in a larger angle of attack. A lower contact pressure can result in a smaller angle of attack.

[0051] The screed lift cylinder can have a pressure control mechanism on the piston side. The pressure control mechanism on the piston side allows the angle of attack to be increased.

[0052] A third aspect of the invention relates to the use of a control device for controlling an angle of attack of a screed arrangement of a road finisher and for controlling a screed height of the screed arrangement.

[0053] The control device can be designed to control the angle of attack and the screed height during operation of the road paver, in particular during the paving of the paving material. The control can be automatic. The control can be continuous. The control can be regular.

[0054] The control device can be configured to receive and process measured values ​​from a first measuring device that determines the screed height and measured values ​​from a second measuring device that determines the angle of attack. The control device can perform the control based on the transmitted measured values ​​of the screed height and the angle of attack.

[0055] The control device can be designed to control a leveling cylinder, in particular two leveling cylinders. The leveling cylinder can change the position, in particular the height, of a drawbar connected to the screed assembly. The control device can be designed to change the screed height by controlling the leveling cylinder.

[0056] The control device can be designed to control a screed lifting cylinder, in particular two screed lifting cylinders. The screed lifting cylinder can change the contact pressure of the screed assembly on the paving material. The contact pressure can be used to adjust the angle of attack of the screed assembly. The control device can be designed to change the contact pressure of the screed assembly by controlling the screed lifting cylinder, in particular the screed lifting cylinders. The control device can be designed to change the angle of attack of the screed assembly by controlling the screed lifting cylinder, in particular the screed lifting cylinders.

[0057] The control device can comprise a multivariable controller. The multivariable controller can be used to control the angle of attack of the screed assembly and to control the screed height of the screed assembly. The multivariable controller can be configured to use the determined angle of attack and the determined screed height as input parameters. The multivariable controller can be configured to control the leveling cylinder, in particular the leveling cylinder, and the screed lifting cylinder, in particular the screed lifting cylinder, in particular based on the determined screed height and the determined angle of attack.

[0058] The control device can have a first controller and a second controller. The first controller can be used to control the screed height of the screed assembly. The second controller can be used to control the angle of attack of the screed assembly. The first controller can be used to control the leveling cylinder, in particular the leveling cylinder. The second controller can be used to control the screed lifting cylinder, in particular the screed lifting cylinder.

[0059] The road paver according to the first aspect of the invention can be used with method steps of the method according to the second aspect of the invention. The method according to the second aspect of the invention can be carried out with a road paver according to the first aspect of the invention. The use of a control device according to the third aspect of the invention can be carried out with a road paver according to the first aspect of the invention and / or using method steps of the method according to the second aspect of the invention.

[0060] The terms "first," "second," "third," and "fourth" are merely designations for a specific element or component and do not necessarily imply a particular order of the components or elements mentioned. For example, the presence of a second component does not necessarily imply the presence of a first component, and vice versa.

[0061] In the following, the invention is explained in more detail using embodiments. Fig. 1 shows a schematic side view of a road paver with a screed arrangement according to an embodiment of the invention. Fig. 2 shows a schematic plan view of a road paver with a screed arrangement according to an embodiment of the invention. Fig. 3 shows a schematic side view of a screed arrangement and a drawbar in a first installation situation according to an embodiment of the invention. Fig. 4 shows a schematic side view of a screed arrangement and a drawbar in a second installation situation according to an embodiment of the invention. Fig. 5 shows a schematic side view of a screed arrangement and a drawbar in a third installation situation according to an embodiment of the invention. Fig. 6 shows a control circuit known from the state of the art for controlling the position of a screed arrangement. Fig. 7 shows a control circuit for controlling the position of a screed arrangement according to an embodiment of the invention. Fig. 8 shows a control circuit for controlling the position of a screed arrangement according to an embodiment of the invention. Fig. 9 shows a control circuit for controlling the position of a screed arrangement according to an embodiment of the invention.

[0062] Fig. 1 shows a road paver 1 according to one embodiment of the invention. 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 towing bars 4, which each run along the sides of the road paver 1. The towing bars 4 are pivotally mounted on the towing vehicle 2 at towing points 5. The screed assembly 3 is arranged behind the towing vehicle 2 with respect to the paving direction 100 and is pulled behind the towing vehicle 2 by the towing bars 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 rearward by a material transport device of the towing vehicle 2 against the paving direction 100 and presented to the screed assembly 3.In the rear area of ​​the towing vehicle 2, a transverse distribution device 7 can be provided, which distributes the paving material orthogonally to the paving direction 100 in front of the paving screed arrangement 3.

[0063] A leveling cylinder 8 is arranged on each side of the road paver 1. The leveling cylinder 8 is connected to the respective drawbar 4 via an intermediate piece 9. The leveling cylinder 8 can be used to adjust the position, in particular the height, of the drawbars 5. 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 drawbar 4. Alternatively, the screed lifting cylinders 10 can also be connected directly to the screed assembly 3. The screed lifting cylinders 10 can be used to adjust the position, in particular the height, and the contact pressure of the screed assembly 3.

[0064] Fig. 2 shows a plan view of a road paver 1 according to an embodiment of the invention. The drawbars 4 are arranged laterally on the towing vehicle 2. The screed assembly 3 comprises a base screed 11 and two extending parts 12. The extending parts 12 are arranged behind the base screed 11 in the paving direction 100. Alternatively, the extending parts 12 can be arranged in front of the base screed 11 in the paving direction 100. The extending parts 12 are arranged laterally next to the base screed 11 in the transverse direction 200. The extending parts 12 can be extended and retracted 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 can be increased by mounting extension parts on the extension parts.

[0065] Fig. 3 shows a schematic side view of the screed assembly 3 and the drawbar 4 in a first paving situation on level ground 13. The extending part 12 is arranged behind the base screed 11 in the paving direction 100. The extending part 12 and the base screed 11 have the same angle of attack 14. The dashed line represents the desired paving height 15 of the finished paving material. The base screed 11 and the extending part 12 are offset in the vertical direction. The vertical offset 16 between the base screed 11 and the extending part 12 is set such that the extending part height 18 corresponds to the base screed height 17. This is usually set manually before paving.

[0066] Fig. 4 shows the screed assembly 3 and the drawbar 4 in a second installation situation. Compared to Fig. 3 the traction point 5 is higher. This results in a larger angle of attack 14. The angles of attack 14 of the base screed 11 and the extension section 12 remain identical. As can be seen from Fig. 4 As can be seen, the base screed height 17 corresponds to the desired paving height 15. Due to the fact that the extendable part 12 is arranged behind the base screed 11 in the paving direction 100, the rear edge of the extendable part 12 sinks further than the rear edge of the base screed 11. Accordingly, the extendable part height 18 is smaller than the base screed height 17. This leads to unevenness of the finished paving material in the transverse direction.

[0067] Fig. 5 shows the screed assembly 3 and the drawbar 4 in a third installation situation. The subsoil 13 has a subsoil slope 19. In Fig. 5 Only the base screed 11 is shown. In the front area of ​​the drawbar 4, a leveling cylinder 8 is mounted, which adjusts the position of the traction point 5. In the rear area of ​​the drawbar 4, a screed lifting cylinder 10 is mounted, which adjusts the contact pressure of the screed assembly 3 on the paving material. Fig. 5 In the position of the screed arrangement 3 shown, 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 angle of attack 14 of the base screed 11 is calculated from the absolute base screed inclination 20 minus the subgrade inclination 19.

[0068] Fig. 6 shows a control loop known from the prior art with a control device 50 for controlling the position of a screed arrangement 3. The screed transmission behavior 51 is influenced by the screed lifting cylinder pressure 52, the subsoil height 53, and the leveling cylinder position 54. The screed lifting cylinder pressure 52 and the subsoil height 53 represent external input parameters. Another input parameter is the desired paving height 15. Based on the screed lifting cylinder pressure 52, the subsoil height 53, and the leveling cylinder position 54, a screed height 55 and an angle of attack 14 are established. The screed height 55 is measured by a measuring device 56 and transmitted to a controller 57. The controller 57 compares the desired paving height 15 with the measured screed height 55 and, if necessary, causes a change in the leveling cylinder position 54. The controller 57 reacts only to a change in the screed height 55.There is no reaction to a change in the angle of attack 14.

[0069] Fig. 7 shows a control circuit according to an embodiment of the present invention with a control device 50 for controlling the position of a screed arrangement 3. The screed transmission behavior 51 is, analogous to Fig. 6 , influenced by the screed cylinder pressure 52, the subsoil height 53 and the leveling cylinder position 54. In comparison to the Fig. 6 In the control loop shown, only the subsoil height 53 is an external input parameter. The desired paving height 15 and the desired angle of attack 58 are specified as target values. The target value for the paving height 15 and / or the target value for the angle of attack 58 can be specified by manual user input. The target value for the paving height 15 and / or the target value for the angle of attack 58 can be specified or suggested by a control system, in particular depending on the paving material. The target value for the paving height 15 and / or the target value for the angle of attack 58 can be determined based on stored values ​​from previous construction projects. Based on the screed lifting cylinder pressure 52, the subsoil height 53 and the leveling cylinder position 54, a screed height 55 and an angle of attack 14 of the screed arrangement 3 are set.The screed height 55 of the screed assembly 3 is measured by a first measuring device 59 and transmitted to a first controller 60. The first controller 60 compares the desired paving height 15 with the measured screed height 55 and, if necessary, causes a change in the leveling cylinder position 54. The setting angle 14 of the screed assembly 3 is measured by a second measuring device 61 and transmitted to a second controller 62. The second controller 62 compares the desired setting angle 58 with the measured setting angle 14 and, if necessary, causes a change in the screed lifting cylinder pressure 52. The first controller 60 reacts to a change in the screed height 55, and the second controller 62 reacts to a change in the setting angle 14.

[0070] Fig. 8 shows a control circuit according to a further embodiment of the present invention with a control device 50 for controlling the position of a screed arrangement 3. In comparison to the Fig. 7 The control loop shown in the figure shows the control loop in Fig. 8 only a first measuring device 59. The first measuring device 59 measures the screed height 55 of the screed assembly 3 and transmits this to the first controller 60 and the second controller 62. The first controller 60 compares the desired paving height 15 with the measured screed height 55 and, if necessary, causes a change in the leveling cylinder position 54. The second controller 62 compares the desired paving height 15 with the measured screed height 55 and, if necessary, causes a change in the screed lifting cylinder pressure 52.

[0071] Fig. 9 shows a control circuit according to a further embodiment of the present invention with a control device 50 for controlling the position of a screed arrangement 3. In comparison to the Fig. 7 The control loop shown in the figure shows the control loop in Fig. 9a multi-variable controller 63. The first measuring device 59 measures the screed height 55 of the screed assembly 3 and transmits this to the multi-variable controller 63. The second measuring device 61 measures the angle of attack 14 of the screed assembly 3 and transmits this to the multi-variable controller 63. The multi-variable controller 63 compares the desired paving height 15 with the measured screed height 55 and calculates a control deviation of the screed height from this. The multi-variable controller 63 compares the desired angle of attack 58 with the measured angle of attack 14 and calculates a control deviation of the angle of attack from this. Based on the control deviation of the screed height and the control deviation of the angle of attack, the multi-variable controller 63 causes a change in the screed lifting cylinder pressure 52 and the leveling cylinder position 54, if necessary. The multi-variable controller 63 can be a MIMO controller (multiple input multiple output controller).

Claims

1. Road paver (1), comprising: a towing vehicle (2), at least one towing bar (4), a screed assembly (3) which is fastened to a towing point (5) of the towing vehicle (2) via the at least one towing bar (4), a leveling cylinder (8) which is designed to adjust a position, in particular a height, of the towing point (5), a screed lifting cylinder (10) which is designed to adjust a contact pressure of the screed assembly (3), a first measuring device (59) which is designed to determine a screed height (55) of the screed assembly (3), a second measuring device (61) which is designed to determine an angle of attack (14) of the screed assembly (3), and a control device (50) which is designed to control the leveling cylinder (8) and the screed lifting cylinder (10).

2. Road paver according to claim 1, wherein the control device (50) comprises a first controller (60) which is designed to control the leveling cylinder (8) based on a control deviation of the screed height (55), and a second controller (62) which is designed to control the screed lifting cylinder (10) based on a control deviation of the angle of attack (14).

3. Road paver according to claim 1, wherein the control device (50) comprises a first controller (60) which is designed to control the leveling cylinder (8) based on a control deviation of the screed height (55), and a second controller (62) which is designed to control the screed lifting cylinder (10) based on a control deviation of the screed height (55).

4. Road paver according to claim 1, wherein the control device (55) comprises a multi-variable controller (63) which is designed 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 angle of attack (14).

5. Road paver according to one of the preceding claims, wherein the second measuring device (61) has a first inclination sensor arranged on the screed arrangement (3) and a second inclination sensor arranged on the towing vehicle (2), wherein the first inclination sensor is designed to determine an inclination angle of the screed arrangement (3) relative to a horizontal plane, wherein the second inclination sensor is designed to determine an inclination angle of the towing vehicle (2) relative to the horizontal plane, wherein the second measuring device is designed to determine the angle of attack (14) of the screed arrangement (3) from the inclination angle of the screed arrangement (3) and the inclination angle of the towing vehicle (2).

6. Road paver according to one of the preceding claims, wherein the second measuring device (61) comprises a rotation angle sensor which is arranged at the towing point (5) of the towing vehicle (2).

7. Road finisher according to one of the preceding claims, wherein the paving screed arrangement (3) comprises a base screed (11) and at least one extending part (12), wherein the extending part (12) is arranged at least partially offset from the base screed (11) in the paving direction of travel (100) of the road finisher (1), and wherein the base screed (11) and the extending part (12) have the same angle of attack (14).

8. Method for controlling a position of a screed arrangement (3) which is fastened to a traction point (5) of a road paver (1), comprising: determining a screed height (55) of the screed arrangement (3), determining an angle of attack (14) of the screed arrangement (3), adjusting the position, in particular the height, of the traction point (5) based on the determined screed height (55), adjusting a contact pressure of the screed arrangement (3) based on the determined angle of attack (14).

9. Method according to claim 8, wherein the adjustment of the position, in particular the height, of the traction point (5) and the adjustment of the contact pressure takes place during operation of the road paver (1).

10. Method according to claim 8 or 9, wherein the adjustment of the position, in particular the height, of the pulling point (5) and the adjustment of the contact pressure are carried out automatically, in particular by a control device (50).

11. Method according to one of claims 8 to 10, wherein the determined screed height (55) and the determined angle of attack (14) are fed to a control device (50) of the road finisher (1), wherein the control device (50) has a multi-variable controller (63) or two separate controllers (60, 61) for controlling the screed height (55) and controlling the angle of attack (14).

12. Method according to one of claims 8 to 11, wherein the adjustment of the position, in particular the height, of the traction point (5) is additionally based on the determined angle of attack (14) and the adjustment of the contact pressure of the screed arrangement (3) is additionally based on the determined screed height (55).

13. Method according to one of claims 8 to 12, wherein the adjustment of the position, in particular the height, of the traction point (5) is carried out by means of a leveling cylinder (8) and the adjustment of the contact pressure of the screed arrangement (3) is carried out by means of a screed lifting cylinder (10).

14. Use of a control device (50) for controlling an angle of attack (14) of a screed arrangement (3) of a road finisher (1) and for controlling a screed height (55) of the screed arrangement (3).

15. Use of a control device according to claim 14, wherein the control device (50) has a multi-variable controller (63), wherein the multi-variable controller (63) is used to control the angle of attack (14) of the screed arrangement (3) and to control the screed height (55) of the screed arrangement (3), or the control device (50) has a first controller (60) and a second controller (62), wherein the first controller (60) is used to control the screed height (55) of the screed arrangement (3) and the second controller (62) is used to control the angle of attack (14) of the screed arrangement (3).

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