Road paver with leveling feedback control for a screed

Abstract

The disclosure relates to a road paver comprising a towing vehicle, at least one tow arm, a screed assembly attached to a tow point of the tow vehicle via the at least one tow arm, a leveling cylinder adapted to adjust a position, in particular a height, of the tow point, a screed lifting cylinder adapted to adjust a contact pressure of the screed assembly, a first measuring device adapted to determine a screed height of the screed assembly, a second measuring device adapted to determine an attack angle of the screed assembly, and a feedback control device adapted to control the leveling cylinder and the screed lifting cylinder. The disclosure further relates to a method for feedback controlling a position of a screed assembly and a use of a feedback control device for feedback controlling an attack angle and a screed height of a screed assembly.

What is claimed is: 
     
         1 . A road paver comprising:
 a towing vehicle;   at least one tow arm;   a screed assembly attached to a tow point of the towing vehicle via the at least one tow arm;   a leveling cylinder adapted to adjust a position of the tow point;   a screed lifting cylinder adapted to adjust a contact pressure of the screed assembly;   a first measuring device adapted to determine a screed height of the screed assembly;   a second measuring device adapted to determine an attack angle of the screed assembly; and   a feedback control device adapted to control the leveling cylinder and the screed lifting cylinder.   
     
     
         2 . The road paver according to  claim 1 , wherein the position comprises a height of the tow point. 
     
     
         3 . The road paver according to  claim 1 , wherein the feedback control device has a first controller adapted to control the leveling cylinder based on a control deviation of the screed height, and a second controller adapted to control the screed lifting cylinder based on a control deviation of the attack angle. 
     
     
         4 . The road paver according to  claim 1 , wherein the feedback control device has a first controller adapted to control the leveling cylinder based on a control deviation of the screed height, and a second controller adapted to control the screed lifting cylinder based on a control deviation of the screed height. 
     
     
         5 . The road paver according to  claim 1 , wherein the feedback control device has a multi-variable controller adapted to control the leveling cylinder and the screed lifting cylinder based on a control deviation of the screed height and a control deviation of the attack angle. 
     
     
         6 . The road paver according to  claim 1 , wherein the second measuring device comprises a first inclination sensor arranged on the screed assembly and a second inclination sensor arranged on the towing vehicle,
 wherein the first inclination sensor is adapted to determine an inclination angle of the screed assembly relative to a horizontal plane,   wherein the second inclination sensor is adapted to determine an inclination angle of the towing vehicle relative to the horizontal plane, and   wherein the second measuring device is adapted to determine the attack angle of the screed assembly from the inclination angle of the screed assembly and the inclination angle of the towing vehicle.   
     
     
         7 . The road paver according to  claim 1 , wherein the second measuring device comprises a rotational angle sensor which is arranged at the tow point of the towing vehicle. 
     
     
         8 . The road paver according to  claim 1 , wherein the screed assembly comprises a base screed and an extension part, wherein the extension part is arranged at least partially offset from the base screed in a paving direction of the road paver, and wherein the base screed and the extension part have the same attack angle. 
     
     
         9 . A method for feedback controlling a position of a screed assembly attached to a tow point of a road paver, comprising:
 determining a screed height of the screed assembly;   determining an attack angle of the screed assembly;   adjusting the position of the tow point based on the determined screed height; and   adjusting a contact pressure of the screed assembly based on the determined attack angle.   
     
     
         10 . The method according to  claim 9 , wherein adjusting the position of the tow point comprises adjusting a height of the tow point. 
     
     
         11 . The method according to  claim 9 , wherein adjusting the position of the tow point and adjusting the contact pressure of the screed assembly occur during operation of the road paver. 
     
     
         12 . The method according to  claim 9 , wherein adjusting the position of the tow point and adjusting the contact pressure of the screed assembly occur automatically. 
     
     
         13 . The method according to  claim 9 , wherein adjusting the position of the tow point and adjusting the contact pressure of the screed assembly occur automatically by a feedback control device. 
     
     
         14 . The method according to  claim 9 , wherein the determined screed height and the determined attack angle are fed to a feedback control device of the road paver, and wherein the feedback control device comprises a multi-variable controller for controlling the screed height and controlling the attack angle. 
     
     
         15 . The method according to  claim 9 , wherein the determined screed height and the determined attack angle are fed to a feedback control device of the road paver, wherein the feedback control device comprises first and second separate controllers, and wherein the first controller is used to control the screed height, and the second controller is used to control the attack angle. 
     
     
         16 . The method according to  claim 9 , wherein adjusting the position of the tow point is additionally based on the determined attack angle, and adjusting the contact pressure of the screed assembly is additionally based on the determined screed height. 
     
     
         17 . The method according to  claim 9 , wherein adjusting the position of the tow point occurs by use of a leveling cylinder, and adjusting the contact pressure of the screed assembly occurs by use of a screed lifting cylinder. 
     
     
         18 . A method for feedback controlling a position of a screed assembly of a road paver, the method comprising using a feedback control device for feedback controlling an attack angle of the screed assembly of the road paver and for feedback controlling a screed height of the screed assembly. 
     
     
         19 . The method according to  claim 18 , wherein the feedback control device comprises a multi-variable controller, the multi-variable controller being used to feedback control the attack angle of the screed assembly and to feedback control the screed height of the screed assembly. 
     
     
         20 . The method according to  claim 18 , wherein the feedback control device comprises a first controller and a second controller, wherein the first controller is used to feedback control the screed height of the screed assembly and the second controller is used to feedback control the attack angle of the screed assembly.