Machine train composed of road milling machine and road finisher, and method for operating road milling machine and road finisher

Abstract

A machine train is composed of a road milling machine that travels in front and a road finisher that travels behind. The road milling machine has a profile data determining device configured so that a sequence of height profile data describing the height of the road surface in the longitudinal direction is determined while the road milling machine advances. For transmission of the height profile data, a data transmission device is provided on the road milling machine and a data receiving device is provided on the road finisher. To change the position of the screed, the road finisher has a levelling device that comprises at least one actuator and a control unit, which is configured so that the control unit generates a control signal for controlling the at least one actuator in accordance with a height profile data set.

Claims

1. A machine train comprising: a road milling machine comprising a first machine frame supported by a first set of crawler tracks or wheels and a milling drum arranged on the first machine frame and configured to mill away material from a road surface, wherein the first set of crawler tracks or wheels of the road milling machine are fastened via lifting columns to the first machine frame; a road finisher that travels behind the road milling machine in a traveling direction and comprises a second machine frame which is supported by a second set of crawler tracks or wheels and on which are arranged a reservoir for material to be laid and a screed for laying material, wherein a position of the screed is adjustable in relation to a reference line or reference surface; at least a first sensor and at least a second sensor positioned on respective first and second sides of the milling drum as seen in a working direction, wherein one of the first sensor and second sensor is configured to measure a distance of a reference point on the road milling machine to a surface on its respective side of the milling drum, and wherein the other one of the first sensor and second sensor is configured to generate a sequence of distance data on its respective side of the milling drum; a transverse incline sensor positioned in association with the road milling machine and configured to measure a transverse incline of the first machine frame; a controller for the road milling machine, configured to generate height profile data based on the sequence of distance data from the other one of the first and second sensor, and control the lifting columns such that when the road milling machine advances, the milling depth on the respective side of the one of the first sensor and the second sensor and the measured transverse incline of the first machine frame when the road milling machine advances are kept substantially constant, regardless of the condition of the ground surface, wherein the distance data from the other one of the first and second sensor changes with movement of the road milling machine in a manner corresponding to a profile of unprocessed road surface, and wherein the generated height profile data accordingly changes with movement of the road milling machine in a manner corresponding to the profile of the unprocessed road surface; and a data transmission device configured to transmit the height profile data to the road finisher.

2. The machine train of claim 1, wherein the road finisher further comprises a data receiving device configured to receive the height profile data.

3. The machine train of claim 1, wherein the road finisher comprises at least one actuator for changing the position of the screed, and a second controller that is configured to generate a control signal for controlling the at least one actuator in accordance with a height profile data set obtained from the height profile data.

4. The machine train of claim 3, wherein the at least one actuator is controlled to change the position of the screed in accordance with the height profile data to level off uneven areas in the profile of the road surface.

5. The machine train of claim 3, wherein the second controller is configured to assess the height profile data statistically in order to obtain the height profile data set.

6. The machine train of claim 5, wherein the second controller is configured so that assessing the height profile data statistically comprises one or more of taking an average value and discarding height profile data lying outside predetermined boundary ranges.

7. The machine train of claim 3, wherein the first controller is configured to assess the height profile data statistically in order to obtain the height profile data set.

8. The machine train of claim 3, wherein the road milling machine comprises a device for determining spatial data, and the first controller is configured to determine spatial height profile data from the height profile data.

9. A method of operating a road milling machine that travels in front and comprises a first machine frame supported by crawler tracks or wheels and a milling drum arranged on the first machine frame that is for milling away material from a road surface, wherein the crawler tracks or wheels are fastened to the first machine frame via lifting columns, and a road finisher that travels behind and comprises a second machine frame which is supported by crawler tracks or wheels and on which are arranged a reservoir for material to be laid and a screed for laying material, wherein a position of the screed is adjustable in relation to a reference line or reference surface, the method comprising: measuring a distance of a reference point on the road milling machine to a surface of unprocessed ground on a first side of the milling drum as seen in a working direction; determining a sequence of distance data in accordance with measured distances of the reference point on the road milling machine to a surface of unprocessed ground on a second side of the milling drum as seen in a working direction; measuring transverse inclines of the first machine frame while the road milling machine advances; generating height profile data based on the sequence of distance data; controlling the lifting columns such that when the road milling machine advances, a milling depth on the first side of the milling drum as seen in the working direction and a transverse incline of the first machine frame are controlled to respective target values, regardless of a ground surface condition, wherein the measured distances of the reference point on the road milling machine to the surface of unprocessed ground on the second side of the milling drum change with movement of the road milling machine in a manner corresponding to a profile of unprocessed road surface, and wherein the height profile data accordingly changes with movement of the road milling machine in a manner corresponding to the profile of the unprocessed road surface; and transmitting the height profile data with a data transmission device to the road finisher.

10. The method of claim 9, further comprising receiving the height profile data by a data receiving device of the road finisher.

11. The method of claim 10, further comprising controlling at least one actuator on the road finisher in order to change the position of the screed in accordance with a height profile data set obtained from the height profile data.

12. The method of claim 11, comprising statistically assessing the height profile data in order to obtain the height profile data set, wherein the statistical assessment of the height profile data comprises taking an average value and/or discarding height profile data lying outside predetermined boundary ranges.

13. The method of claim 9, further comprising obtaining spatial height profile data from the height profile data.

14. The method of claim 9, wherein the screed of the road finisher is controlled in accordance with the height profile data to level off uneven areas in the profile of the road surface.

15. A machine train comprising: a road milling machine for milling away material from a road surface, comprising: a first machine frame supported by a first set of tracks or wheels, a milling drum arranged on the first machine frame, wherein the first set of tracks or wheels are fastened via lifting columns to the first machine frame, a first sensor configured to measure a distance of a reference point on the road milling machine to a surface of unprocessed ground on a first side of the milling drum as seen in a working direction as the road milling machine advances, a second sensor configured to generate signals corresponding to a sequence of distance data in accordance with distances of the reference point on the road milling machine to a surface of unprocessed ground on a second side of the milling drum as seen in the working direction, and a transverse incline sensor configured to measure transverse inclines of the first machine frame while the road milling machine advances; and a road finisher for laying new material on the milled road surface, comprising: a second machine frame which is supported by a second set of tracks or wheels, a reservoir on the second machine frame for material to be laid, a screed for laying material, at least one actuator for changing the position of the screed, and a controller configured to generate a control signal for controlling the at least one actuator and change the position of the screed in relation to a reference line or reference surface, based at least in part on height profile data obtained from the sequence of distance data and which accordingly changes with movement of the road milling machine in a manner corresponding to the profile of the unprocessed road surface, wherein the screed is controlled in accordance with the height profile data to level off uneven areas in the profile of the unprocessed road surface.

16. The machine train of claim 15, wherein the controller is configured to assess the height profile data statistically by one or more of taking an average value and discarding height profile data lying outside predetermined boundary ranges..

17. The machine train of claim 15, wherein the controller is configured to determine spatial height profile data from the height profile data.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) In the following, an embodiment of the invention will be described in detail with reference to the drawings, in which:

(2) FIG. 1 is a side view of a road milling machine in a simplified representation,

(3) FIG. 2 is a simplified perspective representation of a road finisher, and

(4) FIG. 3 is a highly simplified, schematic representation of the machine train composed of the road milling machine and road finisher, with the components that are essential for detecting and transmitting the height profile data.

DETAILED DESCRIPTION

(5) FIG. 1 is a side view of a self-propelled road milling machine for milling off road surfaces, in a simplified representation. The road milling machine 1 comprises a machine frame 3 which is supported by a chassis 2. The chassis 2 of the milling machine comprises front and rear crawler tracks 4 and 5, which are arranged on the right and left sides of the machine frame 3 when viewed in the working direction A. Instead of crawler tracks, it is also possible to provide wheels.

(6) To adjust the height and/or incline of the machine frame 3 relative to the surface of the ground 6, the road milling machine comprises a lifting device 7 that comprises lifting columns 8 and 9 associated with the individual crawler tracks 4, 5 by which the machine frame 3 is supported.

(7) The road milling machine 1 also has a milling drum 10 that is equipped with milling tools 10 and is arranged on the machine frame 3 between the front and rear crawler tracks 4, 5 in a milling drum housing 11 that is closed at the longitudinal faces of a left and right edge protector 12. To remove the milled-off road surface, a conveying device 13 with a conveyor belt 14 is provided. The conveying device 13 is arranged on the rear end of the road milling machine as seen in the working direction A, so that the milled-off material can be loaded from the advancing road milling machine onto a following road finisher. The driver's platform 15 for the machine driver is located on the machine frame 3, above the milling drum housing 11.

(8) Retracting and extending the lifting columns 8, 9 of the lifting device 7 makes it possible to adjust the height and incline of the machine frame 3 and of the milling drum 10 arranged on the machine frame with respect to the surface 6 of the ground. It is, however, generally also possible to change the height and incline of the milling drum with respect to the fixed machine frame.

(9) FIG. 2 is a simplified perspective representation of a self-propelled road finisher 16. The road finisher comprises a machine frame 18 supported by crawler tracks 17 (tracked finisher). Instead of crawler tracks, it is also possible to provide wheels (wheeled finisher). In a front region of the machine frame 18 as seen in the working direction A, a reservoir 19 for holding the material to be laid is arranged. Located at the rear of the road finisher 16 is a screed 20 for laying the material. The driver's platform 21 is arranged between the reservoir 19 and the screed 20.

(10) The screed 20 is configured as a board floating on the material to be laid. For this purpose, the screed 20 is connected to the machine frame 18 so as to be able to move over bars 22 that are provided on both sides of the machine frame 18.

(11) The road finisher 16 has a levelling device 23 (FIG. 3) for levelling off short and elongated uneven areas on the ground so that a roadway of the desired evenness and thickness can be finished. The levelling device 23 has actuators 24 for changing the position of the screed 20, and a controller 23A (FIG. 3) that generates control signals for controlling the actuators 24.

(12) The desired thickness is achieved, in particular, via adjustment of the setting angle of the screed 20, which is determined by the height of a screed traction point. To adjust the screed traction point, the actuators 24 of the levelling device 23 comprise levelling cylinders 26 provided on the sides of the machine frame 18. With the levelling cylinders 26, not only the setting angle of the screed 20 but also the incline of the board can be set transversely to the direction of finishing A.

(13) The controller 23A of the levelling device 23 is configured so that the position of the screed 20 is adjusted on the basis of a height profile data set that comprises a sequence of height profile data describing the height of the road surface 6 in the longitudinal direction.

(14) The road milling machine 1 of FIG. 1 and the road finisher 16 of FIG. 2 are operated according to the invention as a machine train, wherein the road milling machine 1, which travels in front, delivers the height profile data from which the height profile data set for the levelling device 23 of the road finisher 16 that travels behind is obtained.

(15) There follows a detailed description, with reference to FIG. 3, of how the height profile data is obtained by the road milling machine 1 and how the height profile data set is obtained from the height profile data. FIG. 3 is a highly simplified, schematic representation of the machine train composed of the road milling machine 1 and the road finisher 16, with the components that are essential for detecting and transmitting the height profile data.

(16) The height profile data is transmitted from the road milling machine 1 to the road finisher 16. The road milling machine 1 comprises a data transmission device 27 for transmitting the height profile data, and the road finisher 16 comprises a data receiving device 28 for receiving the height profile data. The data transmission device and the data receiving device may be a transmitting and receiving device 27, 28. In the present embodiment, the transmitting device 27 is a radio transmitter, and the receiving device 28 is a radio receiver, so that the signals can be transmitted wirelessly. The radio transmitter and radio receiver may be part of a WLAN.

(17) In the present embodiment, the road surface of a damaged road is being milled off with the road milling machine 1, and the milled-off and reconditioned material is being laid back with the road finisher 16 as a new surface.

(18) The road milling machine 1 moves at a predetermined speed of advance, for example on the right half of the road, wherein the milling drum 10 extends transversely to the working direction A across the width of the right half of the road.

(19) FIG. 3 shows the original profile in the middle of the road (middle gradient) and in the region of the right shoulder of the road (outer gradient). The middle gradient 29 exhibits substantially no depressions or elevations. The outer gradient 30, however, has clearly visible depressions 31 and elevations. The height of the road along a line in the longitudinal direction of the road, i.e., the middle or outer gradient, is plotted on the Y-axis, and the distance covered is plotted on the X-axis. Δzn designates the vertical distance between the middle gradient 29 and the outer gradient 30 at a point an on the distance covered; for example Δz1 designates the vertical distance between the middle gradient 29 and the outer gradient 30 at the waypoint a1. The road is inclined towards the edge by the angle α. The angle α is here dependent on the horizontal distance and vertical distance Δzn between the middle gradient 29 and the outer gradient 30. Because the horizontal distance between the middle gradient 29 and the outer gradient 30 is known, and remains constant over the course of the ground machining, the angle α at the waypoint an is suitable for determining the vertical distance Δzn.

(20) The milling machine comprises a milling depth control device 33 that is for controlling the lifting columns 8, 9 and comprises a first measurement device 33A for measuring the distance of a reference point on the road milling machine 1 to the surface of the unprocessed ground on the left side of the milling drum 10 as seen in the working direction A, and/or a second measurement device 33B for measuring the distance of a reference point on the road milling machine to the surface of the unprocessed ground on the right side of the milling drum 10 as seen in the working direction A.

(21) To detect the height profile, the road milling machine 1 according to the invention with the milling depth control device 33 is preferably operated so that the road surface processed with the milling drum 10 constitutes a copy of the unprocessed surface, i.e. that largely the same layer thickness is always removed in the longitudinal direction over the entire width of the milling drum. For this purpose, the current milling depth is detected by the two measurement devices 33A, 33B on the right or left side of the milling drum 10. If one of the milling depth measurement devices 33A, 33B confirms a deviating milling depth, a corresponding correction takes place. For example, a depression, if present in the edge region of the road, is levelled off by an increase in the milling depth on this side of the machine frame 3, through retraction of the lifting columns 8, 9—for example piston-cylinder assemblies—on this side. If, on the other hand, there is an elevation present in the edge region, then the milling depth is reduced by extension of the lifting columns on this side of the machine frame. If it is assumed that the middle of the road is largely free of bumps in the ground, it follows that scarcely any regulatory control by the milling depth control will be needed on the side of the machine frame that is aligned to the middle of the road. Experience has shown, however, that the edge region of a road requiring repair often has uneven areas (due to subsidence in the curb area, uneven loads, etc.), so that often regulatory controls are needed on the machine side facing the edge region.

(22) Due to the regulatory control by the milling depth control device 33, the transverse incline of the machine frame 3 changes when the milling machine advances. The changing transverse incline may thus be taken as a measure of the depth of the depression in relation to an average height of the road surface, in particular the middle gradient, i.e. the transverse incline of the machine frame describes the height profile of the road surface at the edge of the roadway.

(23) To measure the distance Δx between a reference point on the road milling machine and the unprocessed road surface, the first or second measurement device 33A, 33B may have a distance sensor, which may be a tactile or non-touch distance sensor. For example, the distance sensor may be an ultrasonic sensor. The distance sensor may also be a sensor that detects the position of the left/right edge protector 12 of the milling machine, for example a string potentiometer. The two measurement devices 33A, 33B generate a measurement signal that correlates to the distance received by the milling depth control device 33 of the road milling machine 1. The milling depth control device 33 is configured so that the lifting columns 8, 9 are extended or retracted in accordance with measurement signals in such a manner that when the road milling machine advances, the milling depth is kept substantially constant on the left and right sides of the milling drum 10 as seen in the working direction, regardless of the condition of the road surface. Such a milling depth control device is known from DE 10 2006 020 293 A1.

(24) The road milling machine 1 also has a profile data determining device 36 that comprises a transverse incline sensor 37. The transverse incline a of the machine frame 3 or the milling drum 10, which changes according to bumps in the ground, is acquired by the transverse incline sensor 37 while the road milling machine advances. The transverse incline may be measured continuously during the forward movement, or in predetermined time intervals, in order to generate the height profile data. The height profile data may be, for example, data of the transverse incline sensor 37 that has been read out at regular time intervals by the profile data determining device. From the data of the transverse incline sensor 37, the profile data determining device 36 determines—while the milling machine advances—a sequence of height profile data (Δz1, Δz2, Δz3, . . . , Δzn) describing the height of the profile at the waypoints a1, a2, a3 . . . an. If a road milling machine already has this milling depth control device, additional components for determining the height profile data are not needed.

(25) The profile data determining device 36 may have a global positioning system (GPS) 38 that provides position data (x1, y1), (x2, y2), (x3, y3) . . . (xn, yn) at the points in time at which the data of the transverse incline sensor 37 is read out, i.e. at the waypoints a1, a2, a3 . . . , an, in order to determine spatial height profile data from the height profile data (Δz1, Δz2, Δz3, . . . , Δzn). The profile data determining device 36, which determines a sequence of height profile data (Δz1, Δz2, Δz3, . . . , Δzn) describing the height of the profile at the waypoints a1, a2, a3 . . . an while the milling machine advances, assigns the data (x1, y1), (x2, y2), (x3, y3) . . . (xn, yn) obtained with the GPS system to the height profile data at the individual waypoints. For determining the position data (x1, y1), (x2, y2), (x3, y3) . . . (xn, yn), however, another odometer may also be provided. The position data may also be calculated from the rate of advance and the time that is required by the road milling machine 1 in order to reach a certain waypoint a1, a2, a3 . . . an.

(26) The spatial height profile data Δzn(xn, yn) is used to obtain a spatial height profile data set [Data: (Δz1(x1, y1), Δz2(x2, y2), Δz3(x3, y3) . . . Δzn(xn, yn)] that describes the relative height profile, in the longitudinal direction, of a particular road section, in particular, along the outer gradient.

(27) It is, however, also possible to determine an absolute height profile.

(28) In this case, the absolute height of the middle gradient 29 is determined. If the absolute height of the middle gradient 29 is known, the relative height profile data (Δz1, Δz2, Δz3, . . . , Δzn) can be used to calculate absolute height profile data (z1, z2, z3, . . . , zn) and a spatial absolute height profile data set that describes the absolute height profile in the longitudinal direction of a certain road section, in particular, along the outer gradient.

(29) An assessment device 39, which may be provided in the road milling machine 1 or the road finisher 16, is provided in order to obtain the height profile data set. If the assessment device 39 is provided in the road milling machine 1, the entire data set or a part of the data set is transmitted to the data receiving device 28 with the data transmission device 27. Preferably, the assessment device 39 is provided in the road milling machine 1. The assessment device 39 may then be a component of the milling depth control device 33 of the road milling machine 1.

(30) The assessment device 39 may be configured so that the height profile data is assessed according to known statistical assessment methods. In the present embodiment, the average value can be formed from the measured transverse inclines. It may furthermore be provided in the embodiment that any data lying outside predetermined boundary ranges is discarded before the average value is taken. For these measurement values, it is assumed that incorrect measurements occur, or that the measurement device has not detected the road surface but rather objects—for example, relatively large stones—lying on the road.

(31) In the road finisher 16, the height profile data set may be used to control the actuators 24 of the levelling device 23 of the road finisher 16. The controller 23A of the levelling device 23 may, for example, be configured so that the levelling cylinders 26 are retracted or extended on the basis of the height profile data set. For example, the setting angle and/or the transverse incline of the screed 20 can be adjusted in accordance with the height profile data. In the present embodiment, the transverse incline of the screed 20 changes in accordance with the height profile in such a manner that the depressions on the right side of the road are levelled off. If there is a depression, for example, the incline of the screed 20 is reduced such that a greater amount of material is laid on the right side. With a suitable assessment algorithm, uneven areas on the ground can thus be levelled off.

(32) Alternatively, the necessary changes to the setting angle and/or the transverse incline of the screed 20 may already be determined by the assessment device 39 on the basis of the height profile data set. If the assessment device 39 is provided on the road milling machine 1, it suffices in this instance if only control instructions for the actuators, rather than the entire height profile data set, are transmitted by the data transmission device 27, in particular, to a data receiving device 28.

(33) It is an advantage that the height profile data set determined with the road milling machine 1 travelling in front may comprise data about a relatively large section of the road, without the need to have a large number of sensors in order to determine this data. There is also no need for a jib on the road finisher 16 in order to fasten a plurality of sensors, which would moreover be substantially limited in terms of spatial dimensions to the length of the finisher. Even the gradients of winding roads can easily be acquired and made available to the road finisher.

(34) The milling depth control device 33 of the road milling machine 1 and the levelling device 23 of the road finisher 16 may have, for example, a general processor, a digital signal processor (DSP) for continuously processing digital signals, a microprocessor, an application-specific integrated circuit (ASIC), an integrated circuit composed of logic elements (a field-programmable gate array (FPGA)), or another integrated circuit (IC) or hardware components, in order to control the actuators. A data processing program (software) can run on the hardware components. A combination of the different components is also possible.

(35) An alternative embodiment proposes a milling depth control device that is known in the art, is for controlling the lifting columns 8, 9, and comprises a first measurement device for measuring the distance of a reference point on the road milling machine to the surface of the unprocessed ground on only one of the two sides of the milling drum 10. In the present embodiment, a measurement device 33A is provided only on the left side of the machine frame 3. The milling depth control device 33 is configured so that the lifting columns 8, 9 are extended or retracted in such a manner that when the road milling machine advances, the milling depth on the one of the two sides of the milling drum is kept substantially constant, regardless of the condition of the ground surface. In the present embodiment, the milling depth is kept constant on the left side. A transverse incline control device 40 is also provided that is configured so that the lifting columns 8, 9 are controlled such that the transverse incline of the machine frame 3 when the road milling machine advances is kept substantially constant, regardless of the condition of the ground surface, so that a predetermined transverse incline is produced for the milled-off surface. A result thereof, however, is that the same layer thickness is not always removed on the right side in the longitudinal direction, for example only a slight layer thickness in the region of a depression and a greater layer thickness than the average layer thickness in the region of an elevation. The transverse incline control device may be a component of the milling depth control device, which, in turn, may be a component of a central control and processing unit. The milling depth control device (or the central control and processing unit having the milling depth control device as a component thereof) on the road milling machine may be referred to herein as a “first controller” wherein the controller on the road finisher may accordingly be referred to herein as a “second controller,” or vice versa.

(36) With a second measurement device 33B for measuring the distance of a reference point on the road milling machine to the surface of the unprocessed ground on the other of the two sides of the milling drum 10—on the right side in the present embodiment—a sequence of distance data is generated. In this embodiment, the profile data determining device 36 is configured so that the height profile data is obtained from the distance data of the second measurement device 33B. Such a milling depth control device having two measurement devices on the left and right sides and a transverse incline control for adjusting a certain transverse incline is known from DE 10 2006 020 293 A1.

(37) The previous detailed description has been provided for the purposes of illustration and description. Thus, although there have been described particular embodiments of a new and useful invention, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.