EP3851584B1 - Road finisher with compression control - Google Patents

Description

The present invention relates to a road finisher and a method for operating a road finisher.

In road construction, one often finds a planum, i.e. a subsoil prepared for the application of a road surface, which still has bumps. As a result, when installing the road surface, these bumps must be leveled out in order to obtain a level road surface. To this end, it has hitherto been known to control the leveling cylinders of a road finisher in order to vary the layer thickness of the road surface by means of conventional leveling, so that depressions are leveled out with a thicker layer of paving material and elevations with a thinner layer, so that overall a completely level road surface is paved. However, this has proven to be disadvantageous, since the subsequent re-compacting with a roller causes bumps in the paved road surface again, since the thicker layers have a greater rolling dimension, i.e. an absolute reduction in layer thickness due to the compaction performance of the roller, than thinner layers.

From the U.S. 2010/0129152 A1 It is known to counteract the problem of a higher rolling dimension with thicker layers of material by increasing the paving material in areas of depressions in the planum more than in the area of elevations in the planum, ie the roadway surface is paved unevenly by the finisher. Digital planum data is used for control. However, the method described has disadvantages, such as the sometimes difficult to control change in the installation height, especially when changing the formation height at small intervals.

the EP 2 366 832 A1 describes the installation of a road surface by means of a road finisher, which has a screed with a tamper device, which can be operated transversely to the direction of travel with a variable stroke and variable frequency.

the EP 2 325 392 A2 also describes a method for installing a road surface using a road finisher, the stroke of the compaction unit being automatically adjusted as a function of an installation parameter.

The object of the present invention is to provide a road finisher with an improved control system and an improved method for operating a road finisher.

The object is achieved by a road finisher having the features of claim 1 and a method for operating a road finisher having the features of claim 7. Advantageous developments of the invention are specified in the dependent claims.

A road finisher according to the invention comprises a screed, the screed comprising a tamper. The paver further includes a GNSS (Global Navigation Satellite System) receiver, a material conveyor, and an electronic control system that includes a memory and a data processor. In the memory are digital building data, in particular a target height profile of a road surface to be finished, a target layer thickness of the paving material, a respective degree of pre-compaction dependent on the target layer thickness and, if appropriate, a height profile of a subgrade are stored. The control system is configured to automatically control the compaction performance of the paving screed depending on the target layer thickness in order to pave the paving material for the respective location coordinate point of the road finisher determined with the GNSS receiver with the respective degree of pre-compaction.

In the case of an uneven subgrade, the target layer thickness is variable, so that an even surface or an even road surface is obtained. The compaction performance of the screed can now be controlled in such a way that where the subgrade has a depression, i.e. a greater layer thickness has to be paved, the material is paved with a higher degree of compaction than in an area where the subgrade is elevated and the layer thickness is therefore smaller. According to the invention, the degrees of compaction are selected in such a way that during subsequent compaction by a roller, all areas are compressed by the same absolute value, i.e. the rolling dimension is the same everywhere, i.e. the areas with a higher layer thickness are compressed and compacted less by the roller than the lower areas layer thickness. This means that the material can be paved with an even surface and this evenness is also retained during post-compacting, since the road surface sinks to the same extent everywhere.

A degree of precompression for a respective location coordinate point is preferably stored in the memory of the control system. Thus, the values do not have to be calculated first, but the corresponding control signals can be transmitted directly to the components of the road finisher that are relevant for setting the degree of compaction.

In an expedient variant, the road finisher has a sensor for measuring an actual layer thickness of paving material, with the control system being configured to calculate a deviation of the actual layer thickness from the target layer thickness. With a feedback mechanism, the paving material can be paved exactly with the desired target layer thickness, i.e. until the deviation between the actual and target layer thickness is equal to zero. Ultrasonic sensors, mechanical tactile sensors, laser sensors or other suitable sensors that work with or without an external reference point can be used for this purpose.

The control system is preferably configured to automatically adjust the compaction performance of the screed by controlling the tamper frequency and/or the tamper stroke. The tamper rams the mix under the screed, ensuring there is a sufficient quantity of paving material and compacting it.

In an advantageous variant, the screed comprises a screed plate and/or a pressure bar and the control system is configured to automatically adjust the compaction performance of the screed by controlling the vibration frequency and/or amplitude of the screed plate and/or the pressure bar pressure. With these devices, high degrees of compaction can be achieved.

In a further variant, the control system is configured to automatically adjust the compaction performance of the screed by controlling the paving speed. The paving speed determines the duration of the action of the tamper, smoothing plate and pressure bar compaction units and is particularly suitable for adapting the settings to a required working width.

• Vorhalten von digitalen Bauwerksdaten, insbesondere ein Höhenprofil eines Planums, in einem Speicher eines elektronischen Steuerungssystems,
• Vorhalten von digitalen Bauwerksdaten, insbesondere ein Soll-Höhenprofil eines zu fertigenden Straßenbelags, eine Soll-Schichtstärke eines Einbaumaterials für die Ortskoordinatenpunkte des Planums sowie ein jeweiliger von der Soll-Schichtstärke abhängiger Vorverdichtungsgrad,
• Einbau des Einbaumaterials, wobei die jeweilige aktuelle Position des Straßenfertigers mittels eines GNSS-Empfängers ermittelt wird und das elektronische Steuerungssystem die Verdichtungsleistung der Einbaubohle in Abhängigkeit der Soll-Schichtstärke automatisch steuert, um das Einbaumaterial mit dem jeweiligen von der Soll-Schichtstärke abhängigen Vorverdichtungsgrad einzubauen.

A method according to the invention for operating a road finisher, in particular a road finisher according to one of the embodiments described above, comprises the following method steps:

• Storage of digital building data, in particular a height profile of a planum, in a memory of an electronic control system,
• Provision of digital building data, in particular a target height profile of a road surface to be finished, a target layer thickness of a paving material for the location coordinate points of the planum and a respective degree of pre-compaction dependent on the target layer thickness,
• Installation of the paving material, whereby the respective current position of the road finisher is determined by means of a GNSS receiver and the electronic control system automatically controls the compaction performance of the paving screed depending on the target layer thickness in order to pave the paving material with the respective degree of pre-compaction depending on the target layer thickness.

As already mentioned above, the paving material is paved with a known degree of pre-compaction that depends on the layer thickness. This means that the loss of height due to post-compaction with a roller can also be predicted and the paving material can be paved with a layer thickness that is greater by the thickness of the roller. This ensures that the rolling dimension is the same for all spatial coordinate points. In addition to the target layer thickness of the respective location coordinate point or the current position, one or more target layer thicknesses of the upcoming location coordinate points, i.e. those located further ahead in the direction of travel, can also be taken into account to calculate and control the compaction performance. Likewise can one or more previous values can also be used to ensure a smooth progression of the surface.

The installation of the installation material preferably includes the detection of an actual layer thickness by means of a sensor and the calculation of a difference between the actual layer thickness and the target layer thickness and the road finisher being automatically controlled to minimize the difference. In this way, the essential paving parameters, namely the layer thickness and the degree of pre-compaction, can be automatically monitored and controlled. This allows the paver operator to devote more attention to other paving tasks to be completed. It is conceivable to have the current values of the paving parameters, in particular layer thickness and degree of pre-compaction, shown on a display so that an operator can read them and also intervene in the automatic control and change the parameters. Since the course, i.e. in particular also the values following the current position, of the target layer thickness and the degree of compaction along the paving route is known, all adjustment changes are automatically made by the control system, and corrections are usually only made as part of an automatic feedback mechanism to the paving route Reaching the target values made, whereby an unwanted target value deviation is already prevented.

In an advantageous variant, the electronic control system automatically adjusts the compaction performance of the screed by controlling the tamper frequency and/or the tamper stroke. The tamper can be seen as the first step in screed compaction. On the one hand, it influences the amount of paving material that gets under the screed. On the other hand, the paving material is pre-compacted by it.

In a further advantageous variant, the control system automatically adjusts the compaction performance of the screed by controlling the vibration frequency and/or amplitude of the screed plate and/or the pressure on the pressure bars. This means that high degrees of compaction can also be achieved with greater layer thicknesses.

In a further variant, the control system automatically adjusts the compaction performance of the screed by controlling the paving speed. In particular, the paving speed can be adjusted as a function of the desired layer thickness.

In an expedient variant, the digital building data, which include the height profile of the planum, are transferred from an external data processing system at the beginning of the method transferred to the memory of the electronic control system via radio or cable connection. The external data processing system can be, for example, a laptop, tablet, mobile phone, stationary personal computer, server or the like, and radio transmission can take place using RFID, Bluetooth, WLAN, a mobile phone connection or the like. In this way, the subgrade data, which was previously determined by means of a surface scan with an independent vehicle, for example, can be analyzed, processed and supplemented with dependent, calculated data. This can take place, for example, at a central site monitoring site and the data can then be transmitted to the road finisher on site.

In a preferred variant, the respective compaction performance is calculated by means of an external data processing system as a function of the determined target layer thickness and/or the respective compaction performance is assigned to a location coordinate point as a function of the target layer thickness and the data are then transferred to the memory of the electronic control system. The compression performance and thus the degree of pre-compression can always be calculated or taken from a table-like data record. The calculation using an external system has the advantage that the necessary devices can be easily kept and the data can also be displayed, analyzed and processed using the appropriate EDP devices.

In a further variant, the respective compaction performance is calculated by means of the electronic control system as a function of the determined desired layer thickness and/or the respective compaction performance is assigned to a location coordinate point as a function of the desired layer thickness. These and other calculations can therefore be carried out directly on the paver. This could even be done during operation for each subsequent item, which can save time. In addition, transmission capacities are saved the lower the data volumes received from external sources.

Figur 1:

eine schematische Seitenansicht eines Straßenfertigers,

Figur 2:

eine dreidimensionale Ansicht von Bauwerksdaten,

Figur 3:

eine schematische Ansicht der Bohlenverdichtung von Einbaumaterial bei ebenem Planum,

Figur 4:

eine schematische Ansicht der Walzverdichtung von Einbaumaterial bei ebenem Planum,

Figur 5:

die graphische Darstellung der Änderung des Verdichtungsgrads der Einbaubohle in Abhängigkeit der Schichtstärke bei konstantem Walzmaß,

Figur 6:

eine schematische Ansicht der Bohlenverdichtung von Einbaumaterial bei unebenem Planum,

Figur 7:

eine schematische Ansicht der Walzverdichtung von Einbaumaterial bei unebenem Planum.

Exemplary embodiments of the invention are described in more detail below with reference to the figures. show it

Figure 1:

a schematic side view of a road finisher,

Figure 2:

a three-dimensional view of building data,

Figure 3:

a schematic view of the screed compaction of paving material with level subgrade,

Figure 4:

a schematic view of the roller compaction of paving material with level subgrade,

Figure 5:

the graphic representation of the change in the degree of compaction of the paving screed as a function of the layer thickness with a constant rolling dimension,

Figure 6:

a schematic view of the screed compaction of paving material with uneven subgrade,

Figure 7:

a schematic view of the roller compaction of paving material with uneven subgrade.

Corresponding components are each provided with the same reference symbols in the figures.
figure 1 shows a schematic side view of a road finisher 1, with a material bunker 3 with paving material 5 being shown in a sectional view in a lower area, and the paving material 5 being conveyed by means of a material conveyor 7 through a tunnel 9 to the rear in front of a paving screed 11 and there by a auger 12 is evenly distributed. The road finisher 1 also includes a GNSS receiver 13 which is connected to an electronic control system 15 . The electronic control system 15 includes a memory 17 and a data processor 19. The screed 11 includes a tamper 21, a smoothing plate 23, and a pressure bar 25, it also being possible for several of these components to be present. The paving material 5 is pre-compacted by means of the paving screed 11 and paved with a layer thickness d _B , which in ideal operation corresponds to the target layer thickness ds, on a planum 27 as a road surface 28, with the target layer thickness ds being a rolling dimension s higher than the desired one Final layer thickness d _E , which is present after post-compaction by a roller. A sensor 29, which can be attached to the screed 11 or the chassis of the road finisher 1, is used to measure the actual layer thickness di of the paving material 5. The sensor 29 can also be attached in such a way that it still measures the actual layer thickness di of paving measures, and so the screed 11 can be readjusted. An external data processing system 31, for example a laptop, can be used to send and receive building data, by means of a radio connection via antennas 33 on the road finisher 1 and on the data processing system 31, in which case the antennas 33 can also be suitable for receiving satellite signals for position determination, or via a cable connection 35, may be provided.

figure 2 shows a three-dimensional view of digital building data 37. The planum 27 has a height profile 39 which includes height data for individual location coordinate points 41. This height profile 39 can have been obtained by means of a previous surface scan using an external vehicle. However, it is also possible that a corresponding scanning device is attached to the road finisher 1 itself and the surface scan takes place for a part of the subgrade 27 that is further forward in the direction of travel, while paving material 5 is already in place in a rear part, based on the digital building data 37 already obtained , is installed. The data of the height profile 39 of the planum 27 is enriched with the data of a target height profile 43 of the road surface 28 to be finished. The different desired layer thicknesses ds for the respective location coordinate points 41 are thus stored in accordance with the elevations and depressions of the height profile 39 of the planum 27 . The number of data points or location coordinate points 41 for which subgrade and road surface data are stored can vary depending on the technical specifications for data acquisition and processing, for example the accuracy of the GNSS, and thus represents a form of "resolution". It is also conceivable that the processing of the digital building data 37 includes algorithms that distinguish areas with frequent and/or severe unevenness in the subgrade 27 from areas with few changes and proportionally adjust the number of data points, which on the one hand maintains a high information density and on the other hand the data volume is reduced. The position of the data points 41 in the grid can be influenced by a sensor position. The digital building data 37 includes further data, which was calculated in particular on the basis of the measured data, such as the height profile 39 of the planum 27, such as a desired degree of compaction per location coordinate point 41.

figure 3 shows a schematic view of the screed compaction of paving material 5 with level subgrade 27. The paving material 5 is deposited by means of the material conveyor 7 and the auger 12 in front of the paving screed 11 with a bulk density ps. The paving screed 11, which is pulled in the direction of travel F by the road finisher 1, compacts the paving material 5 to a slab density ρ _B and a layer thickness d _B which is equal to the target layer thickness ds for paving the screed and thus builds the road surface 28. If the subgrade 27 is level, the screed 11 can be used without significant changes to the paving parameters that have been set.

figure 4 shows a schematic view of the rolling compaction of paving material 5 or the road surface 28 laid by the screed 11 with level subgrade 27. The layer thickness d _B is reduced by the rolling dimension s to the final layer thickness d _E for which the roller 45 completes one or more passes. The density of the mounting material 5 increases to the

$$\mathit{Verdichtungsgrad}{k}_W\mathit{der}\mathit{Walze}=k_W=\frac{{\rho }_W}{{\rho }_M}\ast 100\%$$

rolling density ρ _W . Accordingly, a degree of compaction for the screed 11 and the roller 45 can be specified: $$\mathit{degree\; of\; compaction}{k}_B\mathit{the}\mathit{screed}=k_B=\frac{{\rho }_B}{{\rho }_M}\ast 100\%$$

$$\mathit{degree\; of\; compaction}{k}_W\mathit{the}\mathit{roller}=k_W=\frac{{\rho }_W}{{\rho }_M}\ast 100\%$$

Here ρ _M is the density of the Marshall test body, which is produced with a compaction device under laboratory conditions. The density ρ _M essentially corresponds to the maximum density of the paving material 5. The degree of compaction k _B , kw therefore indicates in each case what percentage of the maximum density ρ _M the paving material 5 is brought to with the respective machine, screed 11 or roller 45.

mit m, b, x = konst. und m = Masse, b = Breite, x = Länge in Fahrtrichtung und d = Schichtstärke des betrachteten Abschnitts des Fahrbahnbelags 28. figure 5 shows the graphical representation of the change in the degree of compaction k _B as a function of the layer thickness d _B of the screed 11 with a constant rolling dimension s according to equation 1, which is derived as follows:
The general rule is: $$\rho =\frac{m}{V}=\frac{m}{b\ast x\ast \mathrm{i.e}}$$

with m, b, x = constant and m = mass, b = width, x = length in the direction of travel and d = layer thickness of the section of road surface under consideration 28.

The following therefore also applies: $$k=\frac{{\rho }_1}{{\rho }_2}=\frac{{\mathrm{i.e}}_1}{{\mathrm{i.e}}_2}$$

Assuming that after final compaction of the pavement by the roller, the material density ρ _W approximately corresponds to the Marshall density ρ _M , it follows for the degree of compaction k _B of the pavement $$k_B=\frac{{\rho }_B}{{\rho }_W}=\frac{{\rho }_B}{{\rho }_M}=\frac{{\mathrm{i.e}}_W}{{\mathrm{i.e}}_B}\mathit{With}{\rho }_W\approx {\rho }_M$$

folgt: $$k_B=\frac{d_B-s}{d_B}$$

With $$\mathit{rolling\; gauge}s={\mathrm{i.e}}_B-{\mathrm{i.e}}_W\to {\mathrm{i.e}}_W={\mathrm{i.e}}_B-s$$

follows: $$k_B=\frac{{\mathrm{i.e}}_B-s}{{\mathrm{i.e}}_B}$$

Since the layer thickness d _B is predetermined and varies due to the unevenness of the planum 27, the degree of compaction k _B must be corresponding figure 5 be adjusted in order to obtain the same rolling dimension s for all layer thicknesses d _B , ie on the corresponding function curve (s = 10 mm, 20 mm, 30 mm) in figure 5 to stay.

figure 6 shows a schematic view of the screed compaction of paving material 5 with uneven subgrade 27. The layer thicknesses d _B1 and d _B2 are specified in order to obtain a level road surface 28 at a desired level. The rolling dimension s, by which the height of the road surface 28 is reduced by the rolling compaction, is expediently also taken into account. The respective degrees of compaction k _B1 and k _B2 are calculated according to Equation 1. The electronic control system 15 is able to regulate the compaction performance of the screed 11 by controlling one or more of the compaction units 21, 23, 25 and thus to produce the respective calculated degree of compaction k _B at the location known from the three-dimensional structure data 37. The degree of compaction k _B and thus the density ρ _B as a function of the layer thickness d _B is therefore incorporated in order to obtain a uniform rolling dimension s everywhere during the subsequent subsequent compaction by the roller 45 .

figure 7 shows a schematic view of the rolling compaction of paving material 5 with uneven subgrade 27. The rolling dimension s is the same everywhere due to the adjusted degrees of compaction k _B1 , k _B2 . The road surface 28 that has already been installed by the screed 11 is thus post-compacted by the roller 45 while maintaining this longitudinal evenness. After the roller compaction, the road surface 28 is present with a uniform density ρ _W and a uniform degree of compaction kw as well as the final layer thickness d _E that is variable as a function of the planum 27 .

Claims (14)

1. Road paver (1) with a paving screed (11), the paving screed (11) comprising a tamper (21), and the road paver (1) further comprising a GNSS receiver (13) and a material conveyor (7), the road paver (1) being characterized by an electronic control system (15) comprising a memory (17) and a data processor (19), wherein in the memory (17) digital construction data (37), comprising a target height profile (43) of a road surface (28) to be produced, a target layer thickness (d_S) of the paving material (5), a respective on the target layer thickness (d_S) depending pre-compaction degree (k_B) and, if necessary, a height profile (39) of a roadbase (27) are stored, and the control system (15) is configured to automatically control the compaction performance of the paving screed (11) as a function of the target layer thickness (ds) in order to pave the paving material (5) with the respective pre-compaction degree (k_B) for the respective local coordinate point (41) of the road paver (1) determined with the GNSS receiver (13).
2. Road paver according to claim 1, characterized in that the pre-compaction degree (k_B) for a respective local coordinate point (41) is stored in the memory (17) of the control system (15).
3. Road paver according to one of the preceding claims, characterized by comprising a sensor (29) for measuring an actual layer thickness (d_I) of paving material (5), wherein the control system (15) is configured to calculate a deviation of the actual layer thickness (di) from the target layer thickness (ds).
4. Road paver according to one of the preceding claims, characterized in that the control system (15) is configured to automatically adjust the compaction performance of the paving screed (11) by controlling the tamper frequency and/or the tamper stroke.
5. Road paver according to one of the preceding claims, characterized in that the paving screed (11) comprises a screed plate (23) and/or a pressure bar (25) and the control system (15) is configured to automatically adjust the compaction performance of the paving screed (11) by controlling the vibration frequency and/or amplitude of the screed plate (23) and/or the pressure bar pressure.
6. Road paver according to one of the preceding claims, characterized in that the control system (15) is configured to automatically adjust the compaction performance of the paving screed (11) by controlling the paving speed.
7. Method for operating a road paver (1) according to one of the preceding claims, comprising the following method steps:

   - Storage of digital construction data (37), in particular a height profile (39) of a roadbase (27), in the memory (17) of the electronic control system (15),

   - Storage of digital construction data (37), comprising a target height profile (43) of a road surface (28) to be produced, a target layer thickness (ds) of a paving material (5) for the local coordinate points (41) of the roadbase (27) and a respective on the target layer thickness (ds) depending pre-compaction degree (k_B),

   - Paving of the paving material (5), wherein the current position of the road paver (1) is determined by means of a GNSS receiver (13) and the electronic control system (15) automatically controls the compaction performance of the paving screed (11) as a function of the target layer thickness (ds) in order to pave the paving material (5) with the respective on the target layer thickness (ds) depending pre-compaction degree (k_B).
8. Method according to claim 7, characterized in that the paving of the paving material (5) comprises the detection of an actual layer thickness (di) by means of a sensor (29) and a difference of the actual layer thickness (di) with the target layer thickness (ds) is calculated and the road paver (1) is automatically controlled to minimize the difference.
9. Method according to one of claims 7 or 8, characterized in that the electronic control system (15) automatically adjusts the compaction performance of the paving screed (11) by controlling the tamper frequency and/or the tamper stroke.
10. Method according to one of claims 7 to 9, characterized in that the control system (15) automatically adjusts the compaction performance of the paving screed (11) by controlling the vibration frequency and/or amplitude of the screed plate (23) and/or the pressure of the pressure bar.
11. Method according to one of claims 7 to 10, characterized in that the control system (15) automatically adjusts the compaction performance of the paving screed (11) by controlling the paving speed.
12. Method according to one of claims 7 to 11, characterized in that the digital construction data (37) comprising the height profile (39) of the roadbase (27) is transferred at the beginning of the method from an external data processing system (31) to the memory (17) of the electronic control system (15) by means of a radio or cable connection (33, 35).
13. Method according to one of claims 7 to 12, characterized in that by means of an external data processing system (31) the respective compaction performance is calculated as a function of the determined target layer thickness (d_S) and/or the respective compaction performance is assigned to a local coordinate point (41) as a function of the target layer thickness (ds) and the data (37) is then transferred to the memory (17) of the electronic control system (15).
14. Method according to one of claims 7 to 12, characterized in that by means of the electronic control system (15) the respective compaction performance is calculated as a function of the determined target layer thickness (d_S) and/or the respective compaction performance is assigned to a local coordinate point (41) as a function of the target layer thickness (ds).

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