EP2104768B1 - Road milling machine, and method for positioning the machine frame parallel to the ground - Google Patents

Description

The invention relates to a self-propelled road milling machine, in particular a cold milling machine, according to the preamble of claim 1, and a method for producing the parallelism of the machine frame to the ground according to the preamble of claim 15.

In such road construction machines of the machine frame is supported by a chassis with wheels or crawler tracks, which are connected via lifting columns with the machine frame, the lifting columns make it possible to adjust the machine frame to a certain level, ground parallel or with a predetermined longitudinal and / or transverse inclination.

On the machine frame, a milling drum is mounted for processing a ground or traffic surface.

In the vicinity of the end faces of the milling drum height-adjustable side plates are provided as edge protection on an outer wall of the road milling machine, which rest during operation on the ground or traffic surface on the side ungrounded edges of the milling track. In the direction of travel behind the milling drum is a height-adjustable stripping, which is lowered during operation in the milling track generated by the milling drum to deduct remaining in the milling track milling material. The road milling machine further comprises a control device for controlling the cutting depth of the milling drum and for controlling the adjustment of the lifting columns.

In the known road milling machines there is the problem that when the machine frame is not parallel to the ground, the scraper behind the milling drum does not rest so precisely that a residue-free removal of the machined surface is possible. Furthermore, there is the problem that the belt shoe, which surrounds the conveyor belt, does not lie flat when the machine frame is not parallel to the ground, whereby milled material between belt shoe and still unprocessed floor surface can interpose or the function is performed as hold down inadequate, thereby preventing clods raise the milling drum and put it under the belt shoe. There is also the problem that the control of the milling depth is not sufficiently accurate and therefore, for this reason, the milling depth must be repeatedly measured manually during the milling process. In particular in the cases where a hard traffic area, e.g. Concrete is milled, there is a high wear on the tools, so that the set milling depth is distorted by the decreasing diameter of the cutting circle. Thus, the wear of the tools when milling concrete after only a few 100 m can cause a difference in the cutting radius of 15 mm, so that a measurement of the displacement of e.g. of side plates relative to the machine frame is not sufficiently accurate. If the milling depth is insufficient, time-consuming reworking of the milling track must be carried out. If the milling track is too deep, then more construction material must be reapplied to achieve the desired floor or traffic surface level.

From the EP 1 154 075 A a self-propelled road milling machine is known, with a control for regulating the cutting depth of the milling drum. The lifting state of the rear lifting columns, whose running gears come to lie on already milled surfaces, can be changed to regulate a predetermined milling depth. The lifting state of the front lifting columns, however, is maintained during the milling process.

From the US 4,139,318 A a self-propelled road milling machine with adjustable cutting depth is known in which the milling drum has side plates and a stripping device.

From the US 5,984,420 is a road milling machine with a regulation of the lifting state of lifting columns known.

The invention has for its object to simplify the operation of the road milling machine and to improve the milling process.

To solve this problem serve the features of claim 1 and 15, respectively.

The invention advantageously provides that the control automatically regulates the lifting state of at least one rear and / or front lifting column in the direction of travel for producing the parallelism of the machine frame to the ground or traffic surface or to a predetermined milling plane, the control for producing the parallelism the machine frame to the ground or traffic surface determines the longitudinal inclination of the machine frame relative to the machined or unprocessed soil.

The invention can also be used for recycling machines.

The solution according to the invention has the advantage that the parallelism of the machine frame to the ground or traffic surface is set automatically and the operator does not have to readjust this parallel position independently, in particular also not according to a milling depth control which is also automatic. By keeping the machine frame parallel to the machined or unprocessed ground or traffic surface, the proper functioning of other machine elements, e.g. of the scraper and the belt shoe, guaranteed. In this way, malfunctions are avoided, which are caused by the fact that an inaccurate setting of the parallel position material can put under the belt shoe, floes are thrown, or that the already milled surface can not be deducted clean.

Furthermore, the driver can focus on the actual milling process and is not distracted by manually performed control operations.

The longitudinal inclination can be determined from at least two offset in the direction of travel offset distance values between machine frame and processed or unprocessed soil.

The pitch can be determined from at least a first distance value between the machine frame and the processed ground and at least one offset relative to the first in the direction of travel second distance value between machine frame and unprocessed soil in conjunction with a measured value for the milling depth.

The first or second distance between the machine frame and the worked or unprocessed ground may be from the position of one of the machined ones or unprocessed ground running track drives based on the machine frame can be determined.

The pitch may be determinable from a first distance value between the machine frame and machined ground and a second distance between the machine frame and the processed ground, the second distance value being from the position of the stripping means or from the position of at least one of the machined ground moving track assemblies relative to the machine frame can be determined.

A conveyor belt may be attached to the machine frame, wherein a belt shoe, the roller-side end of the conveyor belt, which is provided for the removal of the milled material, receives.

The pitch can be determined from at least a first distance value between machine frame and unprocessed ground and a second distance value between the machine frame and unprocessed ground, the second distance value from the position of the belt shoe or from the position of at least one of the unprocessed ground running crawler tracks or from the Position of at least one of the side plates can be determined.

The distance values between the machine frame and the processed or unprocessed ground can be determined by means of displacement measuring systems.

The displacement measuring systems can be integrated in the lifting columns or in the hydraulic cylinders of the lifting columns.

The longitudinal inclination of the machine frame can be determined based on the unprocessed soil from the relative angle in the direction of travel between a resting on the ground side plate and the machine frame.

The longitudinal inclination of the machine frame can be determined based on the machined or unprocessed soil by the relative angle between at least one orthogonal to the machine frame extending mast and running parallel to the ground chassis.

The automatic production of the parallelism of the machine frame based on the machined or unprocessed soil can only be done by the controller when the controller performs a readjustment of the milling depth or setting a given milling depth.

The controller may decide whether to control the lift condition of the front and / or rear lift columns to match the routing depth.

The automatic production of the parallelism of the machine frame with respect to the machined or unprocessed soil can be carried out by the control independently of the control of the milling depth.

The control can control the milling depth of the milling drum in the direction of travel on both sides of the machine frame independently of each other.

At least one measuring device can detect the elevation of a first sensing device resting on the ground or traffic surface to be processed and / or the lowering of a second sensing device on the surface of the milling track due to the current milling depth, wherein the control determines the milling depth from the measured values of the at least one measuring device the milling drum determined.

The lifting state of the rear and front lifting columns in the direction of travel can be variable for producing the parallelism of the machine frame to the floor or traffic surface or to the predetermined milling plane such that the machine frame is pivotable about the Fräswalzenachse.

The fact that the regulation of the parallelism of the machine frame takes place in such a way that the machine frame pivots about the milling drum axis ensures that the control of the parallelism does not influence the milling depths, ie the milling pattern.

A method for producing the parallelism of the machine frame to the ground or traffic surface or to a given milling plane in road milling machines, in which a ground or traffic surface is milled by means of a milling drum by the milling machine is lowered for milling according to the predetermined milling depth with the milling drum, determining the longitudinal inclination of the machine frame relative to the processed or unprocessed soil by detecting measured values, and the automatic Rules of Hubzustandes at least one in the direction of travel rear and / or front lifting column for establishing the parallelism of the machine frame to the ground or traffic surface or to the predetermined milling plane in dependence on the longitudinal inclination of the machine frame.

It can be provided at least one measuring device, which was carried out due to the current milling depth increase a resting on the ground or traffic surface first sensing device and / or the lowering of a second sensing device to the bottom of the milling track. The control can determine from the measured values of the at least one measuring device the milling depth in the amount of the stripping device of the milling drum or the second sensing device.

The measurement is preferably carried out at the level of the stripping device, which is arranged close behind the milling drum or immediately behind the stripping device in the case of a separate sensing device.

The second sensing device may consist of the stripping device.

The use of the stripping device as a scanning device has the advantage that no measurement errors caused by unevenness of the milling track. Another advantage is that the scraper is protected at its lower edge against wear.

Alternatively, the controller can determine the current milling depth of the milling drum at the level of the milling drum axis from the measured values of the at least one measuring device. This preferably takes place with the aid of a calculation which can also take into account an inclined position of the machine frame.

The measuring devices preferably consist of path measuring devices. In one embodiment, it is provided that the first sensing device at least one of the two sides on the end faces of the milling drum relative to the machine frame height adjustable and pivotally arranged side plates consists. The side plates are on the ground or traffic surface or are pressed against them, so that their position change relative to the machine frame during operation allow accurate routing depth detection, in addition, a measurement of the change in position of a second sensing device in the milling track relative to the machine frame.

The measuring devices may have cables and cable pull sensors coupled to the first sensing device and / or the second sensing device as displacement measuring devices.

Even with side plates, there is the advantage that they are wear-resistant at their lower edges.

In this case, the measuring devices with the side plates and / or the stripping means coupled cables and associated cable tension sensors may have as displacement measuring means which measure the change in position of the side plates and the stripping relative to the machine frame or the relative displacement of at least one of the side plates in relation to the stripping or the second sensing device.

Preferably, the arrangement of the coupled with the side plates and the stripper cables in a running approximately at the level of the stripping device substantially vertical plane transverse to the milling track.

This can be avoided that due to a different reference plane of the measurement on the side plates in relation to the measurement on the Abstreifschild a measurement error arises.

For this purpose, it may be provided that a cable is coupled on the one hand to the stripping device and on the other hand to at least one of the side plates via a deflection roller, such that a cable pull sensor directly measures the milling depth, for example on the deflection roller.

The measuring devices can detect the displacement of the first sensing device relative to the second sensing device or respectively the displacement of the first and the second sensing device relative to the machine frame.

In a further alternative it can be provided that the stripping device at the lateral edges facing the side plates each have a measuring device which measures the relative displacement of the stripping to the at least one adjacent side plate or the relative displacement of at least one side plate to the stripping.

According to a further alternative embodiment, the stripping device may comprise at least one height-adjustable, in the stripping vertically and linearly guided transversely to the direction of travel, extending beam as the first sensing device, which rests next to the milling track on the ground or traffic surface and its position relative to the stripping, preferably in terms of height and / or inclination, of the measuring device is measurable.

Due to gravity, the side plates can rest on the edges of the ground or traffic surface next to the milling track milled by the milling machine, or alternatively can be pressed onto the edges by hydraulic devices.

The stripping device can be pressed by means of hydraulic devices on the surface of the milling track.

The hydraulic devices for pressing the side plates onto the ground or traffic surface or for pressing the stripping device on the floor of the milling track can have integrated path measuring systems.

For lifting or lowering the side plates and / or the stripping several more preferably two piston-cylinder units may be provided with integrated displacement measuring systems, from whose Wegmesssignalen the controller calculates the current milling depth from the relative difference of the positions of the stripping and the at least one first sensing device.

The controller, which receives the Wegmesssignale the measuring device, can automatically regulate the lifting state of the rear in the direction of travel lifting columns for producing the parallelism of the machine frame to the ground or traffic surface of a desired cutting depth.

The resting on the traffic surface relative to the machine frame resting side plates may have in the direction of spaced measuring devices, the controller from the difference of the signals of the side plates and the stripping device can measure the pitch and / or bank of the machine frame to the ground or traffic surface.

The front and / or rear lifting columns may have a displacement measuring system for detecting the lifting state. The controller, which receives the Wegmesssignale the measuring device, can regulate the state of all lifting columns such that the machine frame has a predetermined slope or a predetermined distance-dependent transverse slope transverse to the direction of travel.

Preferably, the current setpoint for the milling depth of the milling drum is adjusted by means of the front lifting columns.

The current setpoint for the milling depth of the milling drum can be adjusted using the front lifting columns.

The controller, which controls the measurement signals of all measuring devices, sensing devices, i. For example, receives the side plates and / or scrapers, and / or the belt shoe and / or all lifting columns, depending on the Wegmesssignalen the measuring devices and / or the desired location-dependent change of a target value for the milling depth in the course of the processed route, the resulting Adjust the stroke position of the lifting columns.

The zero level of the measuring signals of the measuring devices may be adjustable on the unground ground or traffic surface.

Each lifting column may have at the lower end a support for a wheel or a track drive, and a distance sensor may measure the distance of the carrier to the ground and traffic surface and a measurement signal to a controller for the lifting position of the lifting columns and / or to a control for the Send the milling depth of the milling drum.

The milling drum may extend substantially over the entire working width of the machine frame.

The milling drum can be mounted vertically adjustable in the machine frame.

The control can calculate the current milling depth from the obtained distance measuring signals and generate a control signal for the height adjustment of the milling drum.

In a method for measuring the milling depth in road milling machines in which a ground or traffic surface is milled by means of a milling drum by the road milling machine is lowered for milling according to the predetermined milling depth with the milling drum, where a side plate on at least one side next to the milling track On the unprocessed ground and traffic surface is placed and where a scraper blade is lowered into the milling track generated by the milling drum, measuring the milling depth of the milling track by detecting the measured values of at least a first, the position of the unprocessed ground and traffic surface scanning sensing device in Relation to the measured values of a second sensing device scanning the position of the ground of the milling track or by measuring the measured values of both sensing devices in relation to the machine frame.

In the method, the side edges can be held down next to the milling track of side plates and that at least one of the side plates are used as a first sensing device, wherein the scraper blade is used for removing the milled surface as a second sensing device.

In the method, also the correction of the measured cutting depth value as a function of the distance between the second sensing device and the Rotary axis of the milling drum, if the machine frame of the road milling machine is not parallel to the ground or traffic surface, done.

Fig. 1

eine Kaltfräse,

Fig. 2

eine an dem Abstreifschild befestigte erste Tasteinrichtung,

Fig. 3

zwei Kolbenzylindereinheiten zum Anheben oder Absenken des Abstreifschildes einer Abstreifeinrichtung,

Fig. 4

eine optische Vorrichtung zur Messung der Wegdifferenz zwischen den Seitenschildern und der Abstreifeinrichtung,

Fig. 5

eine Seilzugmesseinrichtung zwischen den Seitenschildern und der Abstreifeinrichtung,

Fig. 6

ein bevorzugtes Ausführungsbeispiel,

Fig. 7a,b,c

eine schematische Darstellung des an dem Abstreifschild der Abstreif-einrichtung entstehenden Messfehlers bei fehlender Parallelität des Maschinenrahmens mit der Boden- und Verkehrsfläche.

Fig. 8

ein hydraulischer Schaltplan eines bevorzugten Ausführungsbeispiels,

Fig. 9

eine vergrößerte Darstellung des Bandschuhs, und

Fig. 10

eine Straßenfräsmaschine, bei der der Maschinenrahmen nicht parallel zur Bodenfläche verläuft.

In the following, embodiments of the invention will be explained in more detail with reference to the drawings. Show it:

Fig. 1

a cold planer,

Fig. 2

a first sensing device attached to the scraper blade,

Fig. 3

two piston-cylinder units for raising or lowering the scraper blade of a scraper device,

Fig. 4

an optical device for measuring the path difference between the side plates and the stripping device,

Fig. 5

a cable measuring device between the side plates and the stripping device,

Fig. 6

a preferred embodiment,

Fig. 7a, b, c

a schematic representation of the on the scraper blade of the stripping device resulting measurement error in the absence of parallelism of the machine frame with the ground and traffic surface.

Fig. 8

a hydraulic circuit diagram of a preferred embodiment,

Fig. 9

an enlarged view of the belt shoe, and

Fig. 10

a road milling machine in which the machine frame is not parallel to the ground surface.

In the Fig. 1 illustrated road milling machine has a machine frame 4, which is supported by a chassis with two front crawler 2 and at least one rear crawler 3. Der Motorrahmen 4 ist mit einem Motorgehäuse 4 verbunden. The chain drives 2, 3 are connected via lifting columns 12, 13 with the machine frame 4. It is understood that instead of the chain drives 2, 3 and wheels can be used.

With the help of the lifting columns 12, 13, the machine frame 4 can be raised or lowered or brought into a predetermined oblique position relative to the ground or traffic surface 8 to be processed. The mounted in the machine frame 4 milling drum 6 is surrounded by a roller box 9, which is open in the direction of travel forward to a first conveyor belt 11, which transmits the milled material in the front region of the machine frame 4 to a second conveyor 13. The second transport device 13, with which the milled material can be dropped onto a truck, for example, is in Fig. 1 not fully represented because of their length. Behind the milling drum 6, a height-adjustable stripping device 14 is arranged, which engages in operation with a scraper blade 15 in the milling track 17 generated by the milling drum 6 and the bottom of the milling track 17 subtracts, so that behind the Abstreifschild no milled material more in the milling track 17th located.

Above the milling drum 6, a control station 5 is arranged with a control panel for the driver for all control functions of the driving and milling operation. This also includes a control device 23 for controlling the milling depth of the milling drum 6.

The side plates 10 arranged on both sides in the vicinity of the end face of the milling drum 6 and the stripping device 14 are provided with measuring devices 16 which enable the determination of the current milling depth at the level of the stripping device 14 or the calculation of the milling depth at the level of the rotation axis of the milling drum. The milling depth is determined in a plane orthogonal to the ground or traffic surface, which runs parallel to the axis of rotation of the milling drum and in which the axis of rotation is located.

In this case, the position of a first sensing device, such as the side plates 10, on the ground or traffic surface 8 and / or the lowering of a second sensing device, such as the stripping device can be detected. Preferably consisting of Wegmesseinrichtungen measuring devices 16 measure the displacements the sensing devices such as the side plates 10 or a beam 20 or the Abstreifschildes 15 in relation to the machine frame 4 or relative to each other.

The embodiment of Fig. 2 shows a bar 20 as a sensing device which rests on the ground or traffic surface 8 and the stripping plate 15 of the stripping device is guided in a linear and orthogonal to the lower edge 19 of the scraper blade 15 extending slot 24. It is understood that two mutually parallel slots 24 may be provided in the scraper blade 15, or that the beam 20 may be performed as a sensing device in other ways on the stripping 14 height adjustable. The measuring device 16 in the form of a displacement measuring device detects the displacement of the beam 20 in relation to the stripping 14. In the case of two horizontally spaced slots 24, it is possible both the milling depth on the left side of the milling track 17 and on the right Side of the milling track 17 to be recorded separately. In addition, this makes it possible to determine an inclined position of the machine frame 4 in relation to the ground or traffic surface 8.

Fig. 3 shows a further embodiment in which the scraper blade 15 of the stripping device 14 by means of hydraulic devices is moved up and down. The hydraulic devices consist of piston-cylinder units 26, 28 with integrated displacement measuring system. This means that the piston-cylinder units 26, 28 not only allow the lifting movement of the stripping device, but also generate a path signal beyond.

How out Fig. 3 As can be seen, the Kolbenzyindereinheiten 26, 28 are coupled at one end to the machine frame 4 and at the other end with the Abstreifschild 15th

Fig. 4 shows an embodiment in which the relative movement between the side plates 10 and the scraper blade 15 is measured directly to detect the cutting depth of the milling track 17. For this purpose, elements 38,40 of the measuring device 16 are arranged, for example, on the side plates 10 and in each case opposite the stripper plate 15, which detect the relative displacement enable the scraper blade 15 in relation to the side plates 10. This displacement corresponds to the milling depth s in Fig. 4 , For example, such a measuring device, which measures the relative displacement, consist of an optical system, for example by reading a scale with an optical sensor, or an electromagnetic or inductive system.

Alternatively, as in Fig. 5 shown the relative displacement measuring system between the side plates 10 and the scraper blade 15 also consist of a cable 22 in combination with a cable pull sensor 21. The cable 22 is coupled on the one hand with the scraper blade 15 of the scraper 14 and on the other hand with at least one of the side plates 10 via a guide roller 35, so that the signal of the cable pull sensor 21 can immediately display the current cutting depth value.

The side plates 10 may themselves be used as the first sensing device by monitoring their position by means of a cable and a pulley sensor or by means of piston-cylinder units 30, 32 with integrated displacement measuring devices in relation to the machine frame 4 or the second sensing device.

For example, the measuring devices can also measure the displacement of the side plates 10 in relation to the machine frame 4. In the case of two measuring devices in the direction of travel front and rear of the side plates 10 is also the possibility of the longitudinal inclination of the machine frame 4 in relation to the ground or traffic surface 8 or by comparing the measured values of both side plates 10 on both sides of the milling drum 6 and the bank of the machine frame 4 to determine.

Fig. 6 showed a preferred embodiment, in which on both sides of the stripping device 15 cables 22 are arranged with attached to the machine frame 4 cable tension sensors 21. The side plates 10 are also provided with cable pulls 22 and pull cable sensors 21 attached to the machine frame 4, on both sides of the machine. The cutting depth s is determined from the difference between the measured values of the cable pull sensors 21 for the side plates 10 and the cable pull sensors 21 of the stripping device 15. The measurement should preferably take place in the same substantially vertical plane to avoid measurement errors.

In FIGS. 7a to 7c the Seilzugsensoren 21 are shown for the side plates 10 and the Abstreifschilder 14, wherein in the drawings, only a cable pull sensor 21 is indicated, because the cable pull sensors are substantially in the same plane one behind the other.

Fig. 7a, b, c should clarify the case in which the ground or traffic surface 8 is not parallel to the machine frame 4, wherein a correction of the milling depth measured value displayed by the measuring devices must be due to an angle error, as by a longitudinal inclination of the machine frame 4, the measuring signal in the amount of Abstreifschildes 15 or a second sensing device in the vicinity of the stripping device 15 is falsified. Due to the fixed geometric conditions, namely the distance of the scraper blade 15 from the axis of rotation of the milling drum 6 can be corrected with knowledge of the angular deviation from the horizontal in the direction of travel of the measured cutting depth value and calculate the current milling depth in the amount of Fräswalzenachse. The angular deviation in the direction of travel can be determined, for example, from the position of the lifting columns 12, 13 of the chain drives 2, 3 or the piston-cylinder units 30, 32.

From the FIGS. 7a to 7c It is also apparent to what extent the side plates 10 are pivotable relative to the machine frame 4. Since the piston-cylinder units 30, 32 are also provided with path measuring systems, these measuring signals can be used to determine the distance of the side plates 10 from the machine frame 4 as an alternative to cable pull sensors 21.

FIG. 7c shows the position of the at least one side plate 10 at ground parallel position of the machine frame 4. The in the FIGS. 7a to 7c shown scraper blade 15 is located on the roller box 9, so that the distance of the scraper blade 15 from the axis of rotation of the milling drum 6 is uniquely determined to allow calculation of the milling depth correction, when the machine frame 4 is not parallel to the ground.

The control unit 23 can calculate the current milling depth at the level of the milling drum axis from the path measuring signals obtained and optionally also generate a control signal for the height adjustment of the milling drum 6.

Preferably, the controller 23, the lifting state of the front in the direction of travel and / or rear, at least one lifting column 13 automatically to establish the parallelism of the machine frame 4 to the ground or traffic surface 8 or to the horizontal or to a predetermined desired milling level.

For this purpose, all measuring devices described so far can also be used to determine the angular position or longitudinal inclination to control the parallelism of the machine frame 4 to the bottom surface.

Fig. 8 shows a schematic representation of a preferred embodiment of a hydraulic circuit diagram of a road construction machine 1. The four lifting columns 12, 13 each actuators are assigned, which allows the height adjustment of the respective lifting column 12,13. The actuators are designed as working cylinders 40, 42, 44, 46 in the lifting columns. Each working cylinder 40, 42, 44, 46 has in each case a first working chamber 48, 52, 56, 60 and a second working chamber 50, 54, 58, 62. The respective first working chamber 48, 52, 56, 60 is separated from the respective second working chamber 50, 54, 58, 62 by a respective piston. An increase in volume of the respective first working chamber 48, 52, 56, 60 and a simultaneous reduction in volume of the respective second working chamber 50, 54, 58, 62 has an extension of the respective lifting column 12,13 and associated therewith a drop in the respective chassis result.

The first working cylinder 40 is the actuator for the lifting column front left, the second working cylinder 42 is the actuator for the right front lifting column, the third working cylinder 44 is the actuator for the lifting column rear right and the fourth working cylinder 46 is the actuator for the lifting column behind Left.

The first working chamber 48 of the first working cylinder 40 is connected to the first working chamber 60 of the fourth working cylinder 46 via a connecting line 68 connected. The second working chamber 50 of the first working cylinder 40 is connected via a connecting line 64 to the second working chamber 54 of the second working cylinder 42. The first working chamber 52 of the second working cylinder 42 is connected via the connecting line 70 to the first working chamber 56 of the third working cylinder 44. The second working chamber 58 of the third working cylinder 44 is in turn connected via the connecting line 66 to the second working chamber of the fourth working cylinder 46. The working cylinders 40, 42, 44, 46 thus form a closed system via the connecting lines 64, 66, 68, 70, whereby ride comfort and stability of the road construction machine 1 are improved.

The connecting line 68 is connected via a further connecting line 72 to a port B of a first 4/3-way valve 84. A 4/3-way valve has four connections and three switching positions. A second port T of the first 4/3-way valve 84 is connected via a connecting line 76 to a port T of a second 4/3-way valve 86. The connecting line 76 is connected via a working line 87 with a pressure medium sump 80. A third port P of the first 4/3-way valve is connected via the connecting line 78 to a second port P of the second 4/3-way valve 86. There is also a working line 79 connected to the connecting line 78, wherein in the working line 79, an oil pump is provided. The working line 79 also opens into the pressure medium sump 80 at the other end.

A third port B of the second 4/3-way valve 86 is connected via a connecting line 77 to the connecting line 70. A fourth port A of the first 4/3-way valve 84 is connected via the connecting line 96 to a fourth port A of the second 4/3-way valve 86.

Furthermore, the connecting line 64 is connected via the connecting line 75 to a port of a 2/2-way valve 94 (two ports, two switching positions). The second connection of the first 2/2-way valve 94 is connected to a connection of a check valve 92 for the connection line 98. The other terminal of the check valve 92 is connected via the connecting line 81 to the connecting line 96. The check valve 92 is blocked for fluid flows from the connection line 81 to the connection line 98. The connecting line 96 is also connected via the connecting line 83 to a terminal of another check valve 90. The other terminal of the check valve 90 is connected via the connecting line 100 to a terminal of a further 2/2-way valve 88. The other terminal of the 2/2-way valve 88 is connected via the connecting line 74 to the connecting line 66. The check valve 90 blocks fluid flows from the connection line 100 to the connection line 83.

The controller 23 controls by adjusting the two 4/3-way valves adjusting the working cylinder 40, 42, 44, 46 and thus the extension and retraction of the lifting columns 12,13. By the extension and retraction of the lifting columns 12,13 the milling depth is set. In one embodiment, the milling depth of the milling drum 6 seen in the direction of travel can be controlled independently on both sides of the machine frame 4, since only the left working cylinder 40, 46 or the right working cylinder 42, 44 can be moved.

The controller 23 controls the parallelism of the machine frame 4 to the ground or traffic surface 8 in the preferred embodiment according to Fig. 8 only when the controller 23 performs a readjustment of the milling depth or a setting of a predetermined milling depth. The controller 23 decides by appropriately setting the two 2/2-way valves 94, 88, whether the front working cylinder 40, 42 and thus the front lifting columns 12 or the rear working cylinders 44, 46 and thus the rear lifting columns 13 are adjusted. The production of the parallelism of the machine frame 4 to the ground or traffic surface 8 is therefore not actively controlled by the controller 23, but passively regulated by deciding on a current adjustment of the milling depth or a new setpoint setting of a given milling depth, whether the amount of oil flowing through the two 4/3-way valves 84, 86 in the front working cylinder 40, 42 and thus the front lifting columns 12 or the rear working cylinder 44, 46 and thus the rear lifting columns 13 is passed. Alternatively, the amount of oil in both the front and in the rear working cylinders 40, 42, 44, 46 are passed simultaneously, whereby the front and the rear lifting columns 12, 13 are adjusted.

Fig. 9 shows the arrangement of a belt shoe 122 on a larger scale. On the machine frame 4, a belt shoe 122 is mounted vertically adjustable. To adjust the height of the belt shoe 122 a fixed to the machine frame 4 piston-cylinder unit 108 is provided. With the help of this Kobenzylindereinheit the belt shoe can be raised in the vertical direction, for example, to overcome obstacles. The belt shoe 122 has ground contact on the underside. When increasing the depth of cut, the position of the belt shoe 122 sets itself by the ground contact automatically.

The belt shoe 122 receives the mill roller side end of the conveyor 102. The bearing of the rear end of the conveyor 102 is a fixed point between the belt shoe 122 and conveyor 102. At the front end of the belt shoe 122 connecting struts 128 are provided on both sides, which prevent pivotal movement of the belt shoe 122 relative to the conveyor 102. The conveyor preferably consists of a conveyor belt 11.

The band shoe 122 consists of a ground-parallel grate 120, which serves as a hold-down and as a sliding shoe. The grate 120 consists of several aligned parallel to the direction of travel grate bars. Laterally, the grate 120 is bounded by vertical side walls 124. At the rear end of the belt shoe 122, a front portion 126 extends approximately parallel to the conveyor belt 11 of the conveyor 102. At the rear end of the belt shoe a protective shield 121 is provided to protect the conveyor belt 11, which prevents the conveyor belt 11 is damaged by sharp-edged material. A slightly inclined in the direction of travel sign 118 is recessed in the upper region of a U-shape to form a passage opening for the processed material.

Position measuring systems, e.g. Ultrasonic sensors or Seilzugsensoren be attached to the belt shoe 122 directly or integrated in the piston-cylinder unit 108. With the aid of the path measuring systems on the belt shoe 122, the distance values between the machine frame 4 and the untreated ground can be determined.

In Fig. 10 a road milling machine 1 is shown whose machine frame 4 is not aligned parallel to the ground surface 8. The lifting columns 12,13 are mounted at the lower end in joints 43 to the respective track assemblies 2,3. To determine the longitudinal inclination of the machine frame relative to the ground surface 8, rotational angle sensors can be provided on the joints 43, which detect the relative angle between the lifting columns 12, 13 running orthogonally to the machine frame 4 and the chain drives 12, 13 running parallel to the ground surface. Alternatively, one of the side plates 10 can also have a rotation angle sensor which detects the relative angle between the side plate 10 resting in parallel on the bottom surface 8 and the machine frame 4.

According to a further embodiment it can also be provided that two measuring devices arranged at a distance from one another in the longitudinal direction of the road milling machine, e.g. with the piston-cylinder units 30, 32 coupled measuring devices detect the longitudinal inclination of the machine frame 4.

Claims (17)

1. A self-propelling road milling machine (1), particularly a cold-milling machine, comprising

   - a track assembly carrying the machine frame (4) via lifting columns (12,13),

   - a milling roller (6) supported on the machine frame (4) for treatment of a ground surface (8) or traffic surface (8),

   - height-adjustable side plates (10) for edge protection, arranged to rest on the ground surface (8) or traffic surface (8) to be treated,

   - a height-adjustable stripping means (14) arranged in the moving direction behind the milling roller (6) and adapted to be lowered, during operation, into the milling track (17) generated by the milling roller (6), and

   - a control means (23) for controlling the milling depth of the milling roller (6), the control means (23) detecting the milling depth of the milling roller (6) from measurement values of at least one measuring means (16),

   characterized in that
   the control means (23) is operative to automatically control the lifting condition of at least one rear and/or front lifting column (12,13) as seen in the traveling direction, for establishing the parallel orientation of the machine frame (4) relative to the ground surface (8) or traffic surface (8) or to a predetermined milling plane, wherein the control means (23), for establishing the parallel orientation of the machine frame (4) relative to the ground surface (8) or traffic surface (8), detects the longitudinal inclination of the machine frame (4) relative to the treated or untreated ground surface (8).
2. The road milling machine of claim 1, characterized in that said longitudinal inclination is detectable from at least two distance values between the machine frame (4) and the treated or untreated ground surface (8), said distance values being displaced relative to each other in the traveling direction.
3. The road milling machine of claim 1, characterized in that said longitudinal inclination is detectable from at least one first distance value between the machine frame (4) and the treated ground surface (8), and at least one second distance value, displaced relative to the first distance value in the traveling direction, between the machine frame (4) and the untreated ground surface (8), in connection with a measurement value of the milling depth.
4. The road milling machine of claim 2 or 3, characterized in that the first or the second distance value between the machine frame (4) and the treated or untreated ground surface (8) is detectable from the position of one of the chain track assemblies running on the treated or untreated ground surface (8), relative to the machine frame (4).
5. The road milling machine of claim 1 or 2, characterized in that the longitudinal inclination is detectable from a first distance value between the machine frame (4) and the treated ground surface (8), and a second distance value between the machine frame (4) and the treated ground surface (8), the second distance value being detectable from the position of the stripping means or from the position of at least one of the track assemblies running on the treated ground surface (8), relative to the machine frame (4).
6. The road milling machine of any one of claims 1 to 5, characterized in that a transport band (11) is arranged on the machine frame (4), a band shoe (122) taking up the roll-side end of the transport band (11) provided for discharge of the milled material, and that the longitudinal inclination is detectable from at least one first distance value between the machine frame (4) and the untreated ground surface (8) and a second distance value between the machine frame (4) and the untreated ground surface (8), the second distance value being detectable from the position of the band shoe (122) or from the position of at least one of the chain track assemblies (2) running on the untreated ground surface (8) or from the position of at least one of the side plates (10).
7. The road milling machine of any one of claims 2 to 6, characterized in that the distance values between the machine frame (4) and the treated or untreated ground surface (8) are detectable with the aid of path measurement systems.
8. The road milling machine of claim 7, characterized in that the path measurement systems can be integrated in the lifting columns (12,13) or in the hydraulic cylinders of the lifting columns (12,13).
9. The road milling machine of claim 1, characterized in that the longitudinal inclination of the machine frame (4) relative to the untreated ground surface (8) is detectable from the relative angle, as seen in the traveling direction, between a side plate resting on the ground surface (8) and the machine frame (4).
10. The road milling machine of claim 1, characterized in that the longitudinal inclination of the machine frame (4) relative to the treated or untreated ground surface (8) is detectable from the relative angle between at least one lifting column (12,13) extending orthogonally to the machine frame (4) and the track assembly (2) extending parallel to the ground surface (8).
11. The road milling machine of any one of claims 1 to 10, characterized in that the automatic establishing of the parallel orientation of the machine frame (4) relative to the treated or untreated ground surface (8) is performed by the control means (23) only when the control means (23) performs a readjustment of the milling depth or a setting of a predefinable milling depth.
12. The road milling machine of claim 11, characterized in that the control means (23) is operative to decide whether the lifting condition of the front and/or the rear lifting columns (12,13) will be controlled for adaptation to the milling depth.
13. The road milling machine of any one of claims 1 to 10, characterized in that the automatic establishing of the parallel orientation of the machine frame (4) relative to the treated or untreated ground surface (8) is performed by the control means (23) independently of the control of the milling depth.
14. The road milling machine of any one of claims 1 to 13, characterized in that the control means (23) is operative to control the milling depth of the milling roller (6) independently on each of both sides of the machine frame (4) as seen in the traveling direction.
15. A method for establishing the parallel orientation of the machine frame (4) relative to the ground surface (8) or traffic surface (8) or to, a predetermined milling plane, for use in road milling machines (1) wherein a ground surface (8) or traffic surface (8) is milled by means of a milling roller (6), in that the road milling machine (1) is lowered together with the milling roller (6) so as to perform the milling in correspondence to a predetermined milling depth,
    characterized by

    - detecting the longitudinal inclination of the machine frame (4) relative to the treated or untreated ground surface (8) by detection of measurement values, and

    - automatically controlling the lifting condition of at least one rear and/or front lifting column (12,13) as seen in the traveling direction, so as to establish the parallel orientation of the machine frame (4) relative to the ground surface (8) or traffic surface (8) or to the predetermined milling plane in dependence on the longitudinal inclination of the machine frame (4).
16. The method according to claim 15, characterized in that said automatic controlling of the lifting condition of the rear and/or front lifting columns (12,13) as seen in the traveling direction for establishing the parallel orientation of the machine frame (4) relative to the ground surface (8) or traffic surface (8) or to the predetermined milling plane, is performed only when a readjustment of the milling depth or a setting of a newly predetermined milling depth is performed.
17. The method according to claim 16, characterized in that the control means (23) is operative to decide whether the lifting condition of the front and/or the rear lifting columns (12,13) will be controlled for adaptation to the milling depth.

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