EP2325392B1 - Method for laying a road paving and paving screed - Google Patents

Description

The invention relates to a screed according to the preamble of claim 1 and a road finisher according to the preamble of claim 9.

A generic screed and a generic paver are known from WO 00/70150 A1 . In the screed of the WO 00/70150 A1 , Figure 7 , 12 known road paver, a tamper driven by an eccentric shaft that can be driven in rotation is provided, the tamper bar of which is driven by a connecting rod driven by the eccentric shaft with essentially vertical work cycles. The paver control system receives measured temperature values of the pavement behind the screed. A controller changes at least the frequency of the work cycles of the tamper bar of the tamper as a function of the measured temperature values.

When paving a pavement made of bituminous or concrete paving material with a road paver, the floating screed has to compact the paving material as evenly as possible over the entire paving width and to create a closed, even structure. The compaction unit, e.g. a so-called tamper or a tamper and an unbalance vibrator, should generate the highest possible, constant and continuous pre-compaction over the pavement thickness, so that different or varying pavement thicknesses have no significant influence on the final compaction. The stroke and the frequency of the tamper influence the pre-compaction and the floating behavior of the screed. The larger the stroke, the higher the pre-compression and the deeper the pre-compression. The frequency can be individually adjusted. EP 0 493 664 A discloses, for example, adjusting the tamper frequency as a function of the paving speed. It is also useful to adapt the tamper stroke to the thickness of the pavement so that the screed paves with the smallest possible positive angle of attack. If the stroke is too large for the pavement thickness, the screed can have a negative angle of incidence, which can lead to an open, cracked surface structure or uncontrollable leveling behavior of the screed, resulting in unevenness. The pavement thickness is specified, for example, by setting the height of the traction points of the screed on the road paver. The frequency and the paving speed must also be adapted to one another. So far, the coordination has been chosen individually so that the screed paves with the smallest possible positive angle of attack. On the other hand, the paving speed determines the effect of the compaction unit on the surface. The paving speed is to be selected so that the most constant possible material supply is guaranteed by the transport vehicles. Since the paving speed has a great influence on the pre-compaction, it should be ensured that the paving screed paves with a small positive angle of attack in order to ensure good evenness, ie the paving speed must enable good pre-compaction. The hub is currently in manually adjusted several stages, whereby the paving operation must be interrupted in each case. However, each stroke stage is only a compromise, as it only fits one pad thickness.

From the information brochure " The right screed for every task ", from Joseph Vögele AG, 68146 Mannheim / DE, No. 2400/10 / 2.1997, page 4 , and from EP 1 310 598 A2 , Figure 3 and 5 , Column 7, it is known to manually adjust the stroke of the compression unit having a tamper in that an eccentric bushing rotatable in a connecting rod driving the tamper bar relative to an eccentric section of the driving Eccentric shaft is rotated. The eccentric bushing is clamped on the eccentric section of the eccentric shaft and thus coupled to the eccentric section in a rotationally fixed manner, and after loosening a clamping screw can be rotated relative to the eccentric section and fixed again. The eccentric shaft is driven by a hydraulic motor, the speed of which is continuously variable, for example. If a certain lining thickness is determined before installation, the stroke is set to this lining thickness. If the lining thickness is changed, the installation must be interrupted and the stroke adjusted to the new lining thickness. The setting is time-consuming and laborious and requires great care.

In the screed of the GB 2091792 A known road paver, a tamper bar is firmly connected to the screed plate of the screed. The screed plate is fastened in a sub-frame which is suspended from a main frame in vibration dampers. An eccentric drive attached to the main frame drives a connecting rod articulated on the subframe, which swivels the subframe around a pivot axis with an elliptical movement stroke in order to simultaneously act as a compacting, smoothing and vibrating device on the paving material. The stroke of the connecting rod is hydraulically adjustable, the axis of a roller bearing arranged in the connecting rod eye being inclined relative to the axis of the drive shaft in a ball joint arranged on a drive shaft.

At the off EP 1 905 899 A2 known screed, a tamper bar that can be driven relative to the screed plate is connected via brackets with two-armed pivot levers which are pivoted about a stationary axis by an eccentric drive. The eccentric drive has an eccentric pin on a driven shaft which engages in a longitudinal slot in the pivot lever. The eccentric drive can be moved manually in the stationary longitudinal guides of the plank base body by means of a crank-spindle drive, which changes the stroke of the tamper bar. A change in the stroke requires an interruption in the paving run of the paver finisher. The crank of the spindle drive can be replaced by a motor.

Out DE 198 36 269 A a method is known for varying the frequency of the tamper as a function of the angle of incidence of the screed, the angle of incidence of the screed being continuously scanned by at least one sensor. The frequency is adjusted automatically, while other machine parameters are set by an operator depending on the respective installation parameters.

Out DE 40 40 029 A a method is known in which the frequency of the tamper is varied during installation depending on the actual installation speed.

U.S. 3,545,349 A discloses a screed with a tamper for pre-compacting paving material, the tamper stroke of which is adjustable by means of an eccentric drive.

The invention is based on the object of specifying a screed and a road paver which enable a paved surface to be of a consistently high quality, e.g. the installation of a pavement with a uniform thickness in the direction of travel and uniform compaction both in and across the direction of travel.

The stated object is achieved with the features of claim 1.

Since at least the stroke of the compression unit is automatically adjusted by the control system as a function of at least one paving parameter such as at least the paving speed and / or the thickness of the pavement, the stroke and the respective paving parameters are in an optimal relationship to one another, from which not only a largely constant pre-compression independent of variations the paving parameters result, but an optimally small positive angle of incidence of the screed is maintained, which ensures a closed and even surface of the pavement and a consistently high quality of the paving. The adjustments can conveniently be made for all connecting rods at the same time, [original page 3, paragraph 3] For this purpose, the automatic, preferably computerized, control system operatively connected to the adjustment gear is provided, either on the screed or in the paver finisher, in the paving parameters as at least the paving speed and / or the covering thickness can be entered or which are present there, and at which, for example, a degree of pre-compression to be generated by the compression unit can be set. The control system then automatically adapts the hub to changes in at least one installation parameter that are emerging while the installation is in progress.

In the paving screed, the adjusting gear, which can be actuated while the paving is in progress, allows the stroke to be adjusted so that the stroke, for example, before or when the paving speed and / or the pavement thickness changes, as they occur during paving either due to external influences or are carried out on purpose largely optimally matches the paving speed and / or the thickness of the pavement, resulting in an optimal and constant pre-compaction and high quality of the pavement. Because the hub adjusts during installation the paving operation does not need to be interrupted to adjust the stroke, and the workload for the staff is relieved. The paver operator or an operator The adjustment can alternatively be made on the screed as required. However, it is particularly expedient for the adjustment to take place automatically as a function of the paving parameters such as the paving speed and / or the thickness of the pavement, so that the uniformly high final quality of the pavement is achieved without any significant influence on the part of the staff.

The paver equipped with this screed makes it possible, thanks to the control system and the manipulated variables generated by it and implemented by actuators, to achieve a uniformly high quality of a paved pavement, with a pavement thickness that is uniform in the paving direction and a pavement thickness both in the paving direction and across in an automatic sequence for this purpose, uniform compression can be regulated without an operator having to solve complicated tasks or select parameters. This is because the manipulated variables, which are implemented at least by actuators to create the stroke and / or the frequency of the tamper, are generated automatically and in a process-oriented manner as a function of relevant process parameters or machine parameters or installation parameters.

Here, the compaction unit comprises at least one tamper, each with several connecting rods in each section of the screed, i.e. in the basic screed, in every extending screed and, if necessary, also in screed extension parts attached to the extending screed. In order to achieve an even better pre-compaction, the respective tamper can be combined with an unbalance vibrator, which acts on the screed plate of the screed with substantially vertically acting unbalance pulses. The vibration frequency can, for example, as is known, be adjustable in a certain range via a flow control valve and, according to the method, can also be automatically adjusted as a function of the at least one installation parameter. If the screed also has a high compaction device (see the above-mentioned technical information "The right screed for every task", page 8) that works with high-frequency hydraulic pressure pulses, the frequency and pressure of which can be adjusted, the high compaction device can also be adjusted depending on such paving parameters are carried out, so that, for example, with varying paving speed and / or extremely uneven pavement thickness, a consistently high final quality of the paved surface results.

For this purpose, the control system should have at least one characteristic curve that is dependent on installation parameters or a characteristic diagram for automatic adjustment of the stroke or the stroke and the frequency of the work cycles of the compression unit.

The adjusting gear can be provided between an eccentric shaft that can be driven in rotation in the screed and an eccentric bushing that is rotatable on the eccentric shaft in a connecting rod that drives the tamper bar with essentially vertical working cycles. The stroke of the tamper bar can thus be adjusted by a relative rotary adjustment between the eccentric bushing and the eccentric shaft. Depending on the relative rotational position of the eccentric bushing on the eccentric shaft, half the stroke of a working cycle results from the sum of the eccentricity of an eccentric section of the eccentric shaft and a partial area up to the maximum of the eccentricity of the eccentric bushing.

Alternatively, the adjusting gear is arranged between an eccentric shaft that can be driven in rotation in the screed and an eccentric bushing, which is non-rotatably arranged on the eccentric shaft but can be displaced transversely to the axis of the eccentric shaft and is rotatably mounted in a connecting rod driving the tamper bar, so that the stroke is caused by a transverse displacement of the eccentric bushing relative to the eccentric shaft is adjustable. The then effective extent of the eccentricity of the eccentric bushing depends on the extent of the transverse displacement of the eccentric bushing relative to the eccentric shaft. The eccentric bushing acts eccentrically, but can be designed as a circular cylinder.

As a further alternative, the adjusting gear is arranged between a bearing block supporting a rotationally drivable eccentric shaft and an adjusting lever that is articulated to a connecting rod driving the tamper bar and adjustable in the bearing block (toggle principle), with the adjusting lever and a push rod drivable by the eccentric shaft in a common joint axis with the connecting rod are coupled in such a way that an adjustment of the adjusting lever in the bearing block changes the effective stroke of the tamper bar generated via the push rod by the rotation of the eccentric shaft. The bearing block has a straight or curved guideway in which a swivel abutment of the adjusting lever engages, which can be displaced by means of the adjusting gear along the guideway and is fixed in selected setting positions, the direction of the guideway pointing at least approximately to the axis of the eccentric shaft. The adjustment of the swivel abutment of the adjusting lever results in a change in the stroke of the tamper bar tapped by the eccentric shaft.

A hydraulically and / or electrically and / or mechanically actuated adjusting gear is provided in the screed, which, if necessary, even while paving is in progress, enables the stroke to be adjusted at any time without having to intervene manually.

In the embodiment with the eccentric bushing rotatable relative to the eccentric shaft, an axially adjustable driver is rotatably mounted in the eccentric shaft and engages in a thread-like guideway of the eccentric bushing rotatable on the eccentric shaft. When the driver is adjusted, preferably electrically and / or hydraulically and / or mechanically, in the axial direction of the eccentric shaft, the eccentric bushing is rotated via the thread-like guideway and fixed again in the selected setting.

In an alternative embodiment, an axially movable adjustment mechanism is arranged in the eccentric shaft in a rotationally fixed manner, which cyclically actuates a rotary indexing mechanism that interacts with the rotatably mounted eccentric bushing in order to rotate the eccentric bushing in steps relative to the eccentric shaft, and in the selected rotational position with the eccentric shaft couple.

In a further alternative embodiment, a tensioning mechanism can be provided between the eccentric shaft and the eccentric bushing which frictionally engages the eccentric bushing or frictionally or positively couples with the eccentric shaft and can be temporarily brought into a release position by an axial release mechanism supported in the screed, in which the coupling between the eccentric shaft and the eccentric bushing is canceled and these two components can be rotated relative to one another or are rotated automatically.

In an embodiment with the eccentric bushing that can be displaced transversely to the axis of the eccentric shaft, at least one guide stone bearing the eccentric bushing and bearing the eccentric bushing is provided with an inclined guide surface, which is adjustable by means of at least one control rod axially displaceable in the eccentric shaft, transversely to the eccentric shaft. The guide block is displaced across the axis of the eccentric shaft via the inclined guide surface in order to adjust the eccentric bushing or to change its effective part of the eccentricity. The eccentric bush does not need to be eccentric here, but can be cylindrical.

It is useful here if the inclined guide surface of the guide block, suitably two diametrically opposed guide blocks, rests axially displaceably on an inclined ramp either in the eccentric bushing or on the control rod.

In the case of the toggle lever mechanism, it is useful if the guide track is arranged in relation to the axis of the eccentric shaft and the joint axis on the connecting rod in such a way that a bottom dead center of the working cycle induced by the eccentric shaft of the tamper bar connected to the connecting rod is independent of the setting position of the swivel abutment of the Adjusting lever remains stationary along the guide track, preferably or for example stationary in relation to a screed plate mounted on a frame of the screed bearing the bearing block. This means that only the top dead center of the work cycle is adjusted in the vertical direction, and the position of the bottom dead center in relation to the screed plate does not change when the stroke is adjusted

In order to be able to record paving parameters or changes to paving parameters and to be able to transmit them to the control system or to be able to enter them into the control system, at least one sensor, preferably several in and across the paving direction, is installed on the paver itself and / or the screed and / or the spars distributed sensors, provided for recording actual installation parameters, the sensors being linked to the control system or being linkable. Since at least relevant paving parameters, such as at least the angle of incidence of the screed, or changes thereof, can be detected via the sensors and transmitted to the control system, the operator is relieved and the quality of the paved surface is consistently high.

In a further expedient embodiment, the road paver and / or the screed have an input and display section on the control system or a machine control linked to the control system for additional or alternative setting of sizes, values or parameters, at least for the stroke and / or the frequency, but also the angle of incidence of the screed is provided, which can be used by the operator in order to enter additional information into the control system as required.

In order to be able to record paving parameters or changes to paving parameters and to be able to transmit them to the control system or to be able to enter them into the control system, at least one sensor, preferably several in and across the paving direction, is installed on the paver itself and / or the screed and / or the spars distributed sensors, provided for recording actual installation parameters, the sensors being linked to the control system or being linkable. Since at least relevant paving parameters, such as at least the angle of incidence of the screed, or changes thereof, can be detected via the sensors and transmitted to the control system, the operator is relieved and the quality of the paved surface is consistently high.

In a further expedient embodiment, the road paver and / or the screed have an input and display section on the control system or a machine control linked to the control system for additional or alternative setting of sizes, values or parameters, at least for the stroke and / or the frequency, but also the angle of incidence of the screed is provided, which can be used by the operator in order to enter additional information into the control system as required.

Fig. 1

eine schematische Seitenansicht eines mit einer Einbaubohle ausgestatteten Straßenfertigers beim Einbauen eines Belages,

Fig. 2

ein Diagramm zur Verdeutlichung zweier Kennlinien bzw. eines Kennfeldes,

Fig. 3

eine Perspektivansicht eines Teiles einer mit einem Verdichtungsaggregat ausgestatteten Einbaubohle,

Fig. 4

eine Perspektivschnittdarstellung einer Ausführungsform einer Hubverstelleinrichtung,

Fig. 5

eine perspektivische Teilschnittansicht einer weiteren Ausführungsform einer Hubverstelleinrichtung,

Fig. 6

einen Längsschnitt einer weiteren Ausführungsform einer Hubverstelleinrichtung,

Fig. 7

einen Längsschnitt einer weiteren Ausführungsform einer Hubverstelleinrichtung,

Fig. 8

eine Perspektivschnittansicht einer weiteren Ausführungsform einer Hubverstelleinrichtung,

Fig. 9

eine Perspektivschnittdarstellung einer weiteren Ausführungsform einer Hubverstelleinrichtung, und

Fig. 10

eine Perspektivansicht einer weiteren Ausführungsform einer Hubverstelleinrichtung.

Embodiments of the subject matter of the invention are explained with the aid of the drawings. Show it:

Fig. 1

a schematic side view of a paver equipped with a screed when paving a pavement,

Fig. 2

a diagram to illustrate two characteristic curves or a characteristic field,

Fig. 3

a perspective view of part of a screed equipped with a compaction unit,

Fig. 4

a perspective sectional view of an embodiment of a stroke adjustment device,

Fig. 5

a perspective partial sectional view of a further embodiment of a stroke adjustment device,

Fig. 6

a longitudinal section of a further embodiment of a stroke adjustment device,

Fig. 7

a longitudinal section of a further embodiment of a stroke adjustment device,

Fig. 8

a perspective sectional view of a further embodiment of a stroke adjustment device,

Fig. 9

a perspective sectional view of a further embodiment of a stroke adjustment device, and

Fig. 10

a perspective view of a further embodiment of a stroke adjustment device.

A paver 1 in Fig. 1 For paving a pavement 6 made of bituminous or concrete paving material 5 on a subsurface 7, a chassis 2 has a paving material bunker 4 and a control panel P of a control, for example with a control system 25, in a driver's cab. Alternatively, the control system 25 could also be arranged elsewhere in the paver 1 or in a screed 3 dragged by the paver, specifically in functional assignment to the control or the control panel P or an external control panel P 'arranged on the screed 3.

The screed 3 is attached to drawbars 8, which are connected on both sides to articulation points 9 of the road paver 1. The articulation points 9 can be adjusted up and down by means of adjusting devices 10, such as leveling cylinders, for example in order to set the thickness S of the covering 6 installed. The screed 3 comprises, for example, a base screed 11 and extending screeds 12 that can be moved thereon, each with a compacting unit 13 comprising at least one tamper 14 or a tamper bar and a screed 18 acting on the paving material 5, preferably with the paving screed 3 having a small positive angle of incidence α works floating compared to a plane parallel to the substrate 7. The tamper bar 14 is cyclical in work cycles for precompaction drivable and performs strokes H with a frequency F. When paving is in progress, the road finisher 1 travels at a paving speed V on the ground 7.

If necessary, the paving screed 3 (in the basic screed 11 and each extending screed 12) additionally contains at least one unbalance vibrator (not shown) for applying vertical pulses to the screed plate 18, and, if necessary, at least one pressure bar of a high-compression device (not shown) at the rear in the direction of travel. The unbalance vibrator and the high compression device are optional options for a screed 3, while the tamper 14 can be part of the basic equipment.

The paving speed V as well as the covering thickness S are paving parameters which, if necessary, can even change or be changed while paving is in progress. The tamper 14 has to produce a pre-compression in the paving material 5, which is loosely poured onto the subsurface 7, which is to be kept at least largely constant regardless of changing paving parameters. Other paving parameters that may be relevant for the pre-compaction can be the type and consistency of the paving material 5, its temperature, the ambient conditions, the construction of the screed 3, and the like.

According to the invention, the pre-compression is kept essentially constant regardless of the installation parameters that change during ongoing installation, in that at least the stroke H of the work cycles of the tamper 14 is adjusted as a function of at least one installation parameter, possibly even automatically, expediently also the frequency F, namely Via the control system 25, which receives or knows at least one installation parameter as a control command variable and on which, preferably, a desired degree of pre-compression is set as the setpoint. The control system 25 can be operated with characteristic curves and / or a characteristic map. Each characteristic curve or the characteristic field is predetermined and stored. The control system 25 is expediently automatic and computerized.

Fig. 2 shows a diagram of the stroke H (or the frequency F) over the covering thickness S (or the paving speed V). The solid characteristic curve H shows how the stroke H is continuously increased with increasing thickness of the covering S (or increasing paving speed V). The measure known from the prior art is indicated in dashed lines to change the stroke H in several stages, each with interrupted paving operations, the diagonally hatched fields X and Y making it clear that the stroke H or the pre-compression changed according to the stair profile over a considerable part of the changes in the thickness S or the paving speed V does not fit.

The solid characteristic curve F illustrates the likewise possible change in the frequency with increasing pavement thickness S or paving speed V. The characteristic curves H, F can be stored in a characteristic map that the control system 25 processes while paving is in progress. The characteristic curve F, H or the map is predetermined in such a way that, with regard to the high and consistent final quality of the installed covering 6, there is always an optimal ratio between the covering thickness and / or the installation speed and at least the stroke H, expediently also the frequency F optimal is. The adjustment of the stroke H, and possibly also of the frequency F, is expediently carried out either automatically and even while the paving is in progress, taking changes in at least one paving parameter such as the paving thickness S and / or the paving speed V, or controlled by the operator.

Fig. 3 illustrates an inner area of the screed 3 with the tamper 14. The tamper bar 14 is shielded on the front side of the screed 3 by a cover 19 (feed spout) and is guided essentially vertically movable between the cover 19 and the front edge of the screed 18. On a frame 17 of the screed 3 carrying the screed plate 18 on the underside, a bearing block 16 is mounted, the relative height of which can be adjusted, for example, by means of an adjusting screw 20 such that the tamper bar 14 assumes a specific position relative to the screed plate 18 at the bottom dead center of each work cycle. In the bearing block 16 (several bearing blocks 16 can be mounted over the length of the frame 17) an eccentric shaft 15 is rotatably mounted, each having an eccentric section 22 with a certain eccentricity. The eccentric section 22 is located in a connecting rod 21 which connects the eccentric shaft 15 to the tamper bar 14. On the eccentric section 22 of the eccentric shaft 15, an eccentric bushing 23, for example in the embodiment shown, is rotatably coupled to the eccentric section 22 via an adjusting gear 24 which is supported on the frame 17 and rotatably mounted in the connecting rod 21. By means of the adjusting gear 24, the eccentric bushing 23 can be rotated relative to the eccentric section 22 of the eccentric shaft 15 and coupled again in a rotationally fixed manner to the eccentric shaft 15 in the respectively set rotational position. The relative rotation of the eccentric bushing 23 with respect to the eccentric section 22 effects an adjustment of the stroke which the connecting rod 21 transmits to the tamper bar 14. The adjustment of the stroke can, preferably, be carried out automatically via the control system 25, which is in operative connection with the adjusting gear 24, specifically as a function of changes in certain installation parameters. Alternatively, the adjusting gear 24 could be controlled or actuated by the operator as required.

The representation of the variable speed drive 24 in Fig. 3 is schematic because the adjusting gear 24 naturally has to act indirectly as a stroke adjusting device on the eccentric bushing 23 via the eccentric shaft 15 due to the rotary movement of the eccentric shaft 15. This is explained in detail with reference to the further embodiment.

The in Fig. 4 The adjusting gear 24 shown, the eccentric bushing 23 is rotatably seated on the eccentric section 22 of the eccentric shaft 15. This is, for example, hollow, in such a way that an internal control rod 27 leads to an adjusting drive 26 located outside the eccentric shaft 15. The control rod 27 is coupled to a driver 28 which is axially adjustable in a groove 29 in the eccentric shaft 15 and rotatably connected to it and which engages with an extension 30 protruding outward from the groove 29 in a thread-like guide track 31 of the eccentric bushing 23.

The eccentric section 22 has a first eccentricity to the axis of rotation of the eccentric shaft 15, but is cylindrical on the outer circumference. The cylindrical outer circumference of the eccentric bushing 23 is eccentric with respect to the cylindrical inner circumference. Since the cylindrical outer circumference of the eccentric bushing 23 is rotatable in the connecting rod 21, and the tamper bar 14 is movable in a defined vertical plane, the extent of the resulting eccentricity from the first and second eccentricities depends on the relative rotational position between the eccentric bushing 23 and the eccentric section 22 is set. The effective extent of the eccentricity determines half the stroke H of a work cycle. By moving the driver 28 in the direction of the axis of the eccentric shaft 15, the stroke H can thus be adjusted continuously between a minimum and a maximum. The eccentric bushing 23 always remains coupled to the eccentric shaft 15 in a rotationally fixed manner. The set axial position of the driver 28 is e.g. held by the adjustment drive 26.

The eccentric shaft 15 is for example on in Fig. 4 left end rotatably mounted in a bearing block not shown here and is from in Fig. 4 right-hand end driven by a hydraulic motor, not shown. The adjustment drive 26 can accordingly be in front of the left-hand end Fig. 4 be arranged in the screed or on the frame 17.

Fig. 5 differs mainly from Fig. 4 that the adjusting gear 24 contains the axially displaceable driver 28 in the outwardly open groove 29 of the eccentric shaft 15 so that the adjusting drive 26 engages from the outside of the eccentric shaft 15 via the control rod 27. The extension 30 of the driver 28 engages in the thread-like guide track 31 of the eccentric bushing 22, which is relatively rotatable on the eccentric section 22 of the eccentric shaft 15 is seated, but remains non-rotatably coupled to the eccentric shaft 15 via the driver 28, the groove 29 and the extension 30 in every axial position of the driver 28.

This in Fig. 6 The adjusting gear 24 shown has a rotary indexing mechanism which is actuated cyclically by the adjusting drive 26 supported, for example, on the frame 17 of the screed, in order to rotate the eccentric bushing 23 relative to the eccentric section 22 of the eccentric shaft 15. The eccentric bushing 23 is rotatably mounted in the connecting rod 21 via at least one roller bearing 32. In the eccentric section 22, at least one axial groove 29 is provided, in which an adjusting mechanism 30 is arranged so as to be axially movable but non-rotatably coupled to the eccentric shaft 15. At the left-hand end of the adjusting mechanism 33 in Fig. 6 a sawtooth toothing 34 (circumferential toothing) is provided, as well as a sawtooth toothing 35 offset in the circumferential direction at the right-hand end of the adjustment mechanism 33. The eccentric bushing 23 has corresponding sawtooth toothing 37 and 36 at both ends. The axial length of the eccentric bushing 23 between their sawtooth teeth 36, 37 is slightly shorter than the clear width between the sawtooth teeth 35, 34. Via this difference in width, the adjusting mechanism 33 can be axially adjusted hydraulically by means of, for example, an annular piston 41 of the adjusting drive 26 (hydraulically actuated annular chamber 40). The left-hand end of the adjustment mechanism 33 is supported on a spring 39 of a stop 38 on the eccentric shaft 15.

To rotate the eccentric bushing 23 on the eccentric section 22, the adjusting mechanism 33 is derived from the in Fig. 6 The position shown is adjusted to the left by the annular piston 41 until the teeth 34, 37 are released and the teeth 35, 36 mesh with one another. By means of a circumferential offset between at least the toothings 34 and 35, the eccentric bushing 23 is rotated by one tooth pitch. The pressure in the annular chamber 40 is then reduced, so that the spring 39 returns the adjusting mechanism 33 to the position shown in FIG Fig. 6 shifts the position shown, and, for example, rotates the eccentric bushing 23 by a further tooth pitch, which is then coupled to the eccentric section 22 in a rotationally fixed manner.

In Fig. 7 if the adjusting gear 24 has the annular piston 41 as adjusting drive 26. The adjustment drive 26 can be supported on the frame 17 of the screed. The annular piston 41 acts directly on one axial end of the eccentric bushing 23, which is axially supported by the spring 39 supported on the stop 38 on the eccentric shaft 15 via a stop ring 42 and a roller bearing 43 on a conical section 22 'of the eccentric section 22 of the eccentric shaft 15 is pressed and rotatably coupled to the eccentric shaft 15. The eccentric bushing 23 can be moved against the force of the spring 39 by the annular piston 41 from the in Fig. 7 Adjust the position shown to the left so that the frictional engagement with the conical section 22 'is released or loosened, and the eccentric shaft 15 can be rotated relative to the eccentric bushing 23 in the roller bearing 43, for example, until the annular piston 41 is pulled back again and the eccentric bushing 23 is released by the spring 39 are brought into renewed frictional engagement with the conical section 22 '. Alternatively, for example similar to in Fig. 6 , the relative rotational movement can also be carried out on the eccentric bushing 23. The connecting rod 21 makes in the embodiment in Fig. 7 these slight axial movements of the eccentric bush 23 with. Alternatively, the roller bearing 32 could have an axial play in the connecting rod 21 or on the eccentric bushing 23. In an alternative not shown, the eccentric bushing 23 could even be coupled in a rotationally fixed manner to the conical section 22 'by a toothing.

At the in Fig. 8 The embodiment shown of the stroke adjusting device with the adjusting gear 24 is different from the previously described embodiments of Figures 4 to 7 the eccentric bushing 23 is not rotated relative to the eccentric section 22 of the eccentric shaft 15, but shifted transversely to the axis of the eccentric shaft 15 in order to change the total effective eccentricity and thus the stroke.

The eccentric bush 23 can e.g. with coaxial inner and outer cylindrical perimeters, i.e. circular cylindrical, designed and rotatably arranged on two opposite guide stones 44, which are displaceable in outwardly open grooves of the drilled eccentric shaft 15 transversely to the axis of the eccentric shaft 15 and are rotationally fixed with the eccentric shaft. Each guide stone 44 has an inclined guide surface 45 on the inside, which rests on an inclined guide ramp 47 of a control rod 46, which is axially displaceable in the eccentric shaft 15 by means of the adjustment drive 26 and can be fixed in the selected setting position. The adjustment drive 26 can be designed hydraulically, electrically or mechanically. Although the eccentric bushing 23 is cylindrical (favorable in terms of production technology), it acts eccentrically relative to the eccentric section 22.

In the embodiment of Fig. 9 that are functionally of the embodiment of Fig. 8 is similar, two diametrically opposite axial grooves 29 are formed in the eccentric section 22 of the eccentric shaft 15, in which the guide blocks 44 are coupled to the eccentric shaft 15 in an axially displaceable and rotationally fixed manner. A control rod 46 ′, which is coupled or can be coupled to the adjustment drive 26, acts on each guide block 44. The inclined guide surface 47 'is formed on the outside of the guide block 44 and engages in an axial groove on the inner surface of the eccentric bushing 23. The inclined guide ramp 45 'is formed in this axial groove, so that the eccentric bushing similar to FIG Fig. 8 is displaced transversely to the axis of the eccentric shaft and remains coupled to the eccentric shaft 15 in a rotationally fixed manner. Here, too, the eccentric bushing 23 can be cylindrical.

In Fig. 10 The adjusting gear 24 is incorporated into a toggle lever mechanism via which the rotary movement of the eccentric shaft 15 with its eccentric section 22 is transmitted to the connecting rod 21, to which the tamper bar 14 is attached, via a push rod 48 rotatably mounted on the eccentric section 22 and a hinge axis 49. One end of an adjusting lever 50 is articulated to the connecting rod 21, preferably on the same hinge axis 49, which is supported by a swivel abutment 51 (eg a pin) in a guide track 52 of the bearing block 16 ′ of the eccentric shaft 15. The bearing block 16 'can be fixed on the frame 17 of the screed. The guide track 52 is, for example, a straight or arched, elongated slot in the bearing block 16 ′ and extends in a plane which cross-cuts the eccentric shaft 15. The adjusting drive 26 is effective between the bearing block 16 ′ and the swivel abutment 51 in order to adjust the swivel abutment 51 within the guide track 52. As a result, the eccentricity picked up by the eccentric section 22 and transmitted to the connecting rod 21 by the adjusting lever 50 or the stroke of the tamper bar 14 changes.

The guide track 52 is expediently designed and arranged in relation to the axis of the eccentric shaft 15 and the hinge axis 49 in such a way that, regardless of the adjustment position of the swivel abutment 51 in the guide track 52, the bottom dead center of the work cycles of the tamper bar 14 remains stationary in relation to the screed plate 18, that is, only the top dead center is shifted during the stroke adjustment.

The rotation of the eccentric shaft 15 moves the push rod 48 back and forth essentially parallel to the top of the frame 17 via the eccentric section 22. This oscillating movement causes, via the common hinge axis 49, a swiveling movement of the adjusting lever 50 about the swivel abutment 51, following a segment of a circular arc. The adjusting lever 50 derives an essentially vertical stroke component for the connecting rod 21 from this. The extent of this stroke component is changed by adjusting the pivot abutment 51 in the guide track 52.

The articulation points 9 of the drawbars 8 of the road finisher 1 of Fig. 1 are height-adjustable with the leveling cylinders 10, for example via actuators 10 '(hydraulic valves or the like.) and affect the angle of incidence α of the screed 3. The angle of incidence α should be positive but with an optimal size, ie not too flat and not too steep and is made by the Control system 25 kept in optimal size. In addition, lifting cylinders 28 are articulated on the chassis 2, which engage the drawbars 8 and serve to position the screed 3 excavated for transport, for example, or to relieve the screed or, if necessary, to increase the bearing pressure of the screed 3. The tamper 14 of the compaction unit 13 is (see Fig. 3 ) can be operated, for example, by means of an eccentric drive with a selectable stroke H and a selectable frequency F.

A speed selector 26 for setting the paving speed V is provided in the control panel P or external control panel P '. The speed selector 26 can optionally also be adjusted by the control system 25 by an actuator (not shown) in order to change the paving speed V. The paving speed V is detected by a symbolically indicated sensor 31 and transmitted to the control system 25. The sensor 31 can be placed in the road paver, for example in the control panel P or on a travel drive, or it can scan a reference on the ground 7. An input section 27 for inputting parameters and / or displaying parameters can be provided in the control panel P or in the control system 25. At least one actuator 28 ', for example a solenoid-operated hydraulic valve, is assigned to the lifting cylinders 28. Furthermore, at least one sensor 30 can be provided as equipment of the road paver 1, which detects the temperature, density or consistency of the paving material, for example immediately in front of the paving screed 3, and if necessary transmits it as information to the control system 25. This recorded information could also be entered by an operator. For example, at least one sensor 29 is provided on the screed 3, which detects the angle of incidence α of the screed relative to the ground 7. This sensor 29 could also pick up the angle of attack α on the drawbars 8. Several sensors 29 can be provided over the installation width. Furthermore, a sensor 37 can be provided for picking up the thickness of the covering S, which, for example, scans the subsurface 7 or a reference (not shown) on the subsurface 7.

In the road finisher 1 or the paving screed 3, actuators for setting the tamper stroke H or the tamper frequency F are provided and can be made to convert control signals by means of control signals generated by the control system 25. For example shows Fig. 3 the an actuator for the gear 24 forming the tamper stroke H for rotating the eccentric bushing 23 relative to the eccentric section 22. The setting of the tamper stroke H, which is matched to the installation parameters, takes place automatically via the control system 25. The eccentric shaft 15 is driven to rotate, for example by a hydraulic motor 32. Its speed determines the tamper frequency F. A solenoid-operated valve, for example a proportional flow control valve, can be used as the actuator 33 for the hydraulic motor 32, to which control signals can be applied by the control system 25.

By means of the control system 25, among other things, a number of different machine or construction site or paving material parameters are automatically regulated as a function of one another in order, for example, to minimize error rates in the built-in covering 6 and to increase the quality of the built-in covering 6.

The tamper 14 has to compact the loosely placed paving material 5 to such an extent that a load-bearing capacity sufficient for the screed 3 is created. Only then is it ensured that the screed 3 with its screed plate 18 is dragged floating with a favorable angle of attack α. The tamper stroke H, the tamper frequency F, the paving speed V and the angle of attack α are heavily dependent on one another. If, for example, the paving speed V is reduced, this has an effect on the pre-compaction of the paving material while the tamper frequency and leveling cylinder setting remain the same. The load-bearing capacity of the paving material increases, so that the screed 3 continues to float and the angle of incidence α is reduced. If, on the other hand, the paving speed is increased without increasing the tamper frequency, the load-bearing capacity of the paving material is reduced and the paving screed paves with a larger angle a, but with a smaller pavement thickness S. In order to minimize or avoid such influences on the final quality of the built-in covering 6, according to the invention, the control system 25 automatically controls and regulates at least manipulated variables for the compacting unit 13 or the tamper 14 depending on the relevant processes or machine parameters. In particular, a constant and optimal compaction of the paving material over the entire paving width of the screed takes place in this way as a contribution to quality assurance.

For example, the angle of incidence α is detected by means of the sensor 29 or a plurality of sensors 29 distributed in the transverse direction and transmitted to the control system 25, or a controller responsible there specifically for this installation parameter, in order to adapt the tamper stroke H when the angle of incidence α changes, so that the angle of attack α again an optimal value is returned or is not able to change appreciably, so that the target layer thickness S is achieved with constant optimal pre-compaction.

As a secondary aspect, the angle of incidence α can vary over the paving width of the screed 3. The control system 25 can then undertake the corresponding adjustment of the tamper stroke H for each tamper 14 individually, so that despite the covering thickness S varying transversely to the paving direction, the compression remains uniform over the paving width.

Taking into account the detected angle of incidence α or its detected changes, the tamper stroke H and the tamper frequency F can also be adjusted via the control system 25 and, if necessary, an adjustment of the leveling cylinder 10 in addition to or as an alternative to an adjustment of the tamper frequency F can be carried out.

The adaptation of the tamper frequency F can be carried out in a particularly simple manner in that when the tamper stroke H changes, the tamper frequency F is automatically adapted in accordance with a characteristic curve or in a characteristic diagram that is entered into the control system or is available there.

A relevant paving parameter is, for example, the density or consistency of the paving material 5. If the road paver 1 is equipped with a sensor 30, as mentioned, by means of which the density or consistency of the paving material can be detected, then the recorded value is compared with a target value, and if there is a deviation from the setpoint, the control system 25 adjusts, for example, the tamper stroke H and / or the tamper frequency F and / or the leveling cylinder setting, so that if there is a deviation in the detected density or consistency, the angle of attack is essentially maintained and the same Compression and evenness and thus quality of the covering 6 can be achieved.

The paving speed V is also a decisive paving parameter, since in the event of a change the tamper stroke H and / or the tamper frequency F and / or the leveling cylinder setting must be adapted, for example via the automatic control system 25.

Another important installation parameter is the rigidity of the installation material 5 and / or its temperature. These installation parameters can for example be used individually or in combination by means of the sensor 30 or a stiffness and a temperature sensor detected and transmitted to the control system 25, or entered by an operator at section 27 after detection, whereupon the control system, if advised by the detected values, adjusts the tamper stroke H and / or the tamper frequency F and / or the leveling cylinder setting accordingly. As an additional or alternative adjustment, an adjustment can also be made to the lifting cylinders 28, for example to relieve the screed 3 more during paving or to load it more forcefully in the direction of the subsurface 7, again with a view to making the angle of incidence α as uniform as possible hold, and let the screed 3 work with even compression of the surface 6.

Essentially, this type of automation minimizes error rates and costs and improves quality, with considerable relief for the operator or operators of the road finisher being an automatic but welcome consequence of this method.

Claims (11)

1. A screed (3) for road pavers (1), comprising a compaction unit (13), particularly a tamper (14) with a tamper bar (14'), that is drivable at cyclical work cycles with selectable stroke (H) and selectable frequency (F) for pre-compacting a pavement (6) made from paving material (5), wherein the tamper (14) comprises a rotatable eccentric shaft (15) with respect to a connecting rod (21) which drives the tamper bar (14') at substantially vertical working cycles, wherein the compaction unit (13) comprises an adjusting mechanism (24) for the remote-controlled adjustment of the stroke (H) of the compaction unit, wherein the adjusting mechanism (24) can be operated hydraulically and/or electrically and/or mechanically during the ongoing paving work, wherein an automatic control system (25) is provided which is operatively connected to the adjusting mechanism (24), and into which paving parameters, such as the paving speed (V) and/or the pavement thickness (S) as well as a target precompaction degree producible by the compaction unit, can be entered or in which said parameters can be stored,
   characterized in that

   A. the adjusting mechanism (24) is arranged between the rotatingly drivable eccentric shaft (15) in the screed (3) and an eccentric bush (23) which is rotatable on the eccentric shaft (15) in a connecting rod (21) driving the tamper bar (14) at substantially vertical work cycles, in such a manner that the stroke (H) of the tamper bar (14) is adjustable by a relative rotational adjustment between the eccentric bush (23) and the eccentric shaft (15), wherein in the eccentric shaft (15) a driver (28) which is axially adjustable, preferably electrically and/or hydraulically and/or mechanically adjustable, is supported in a rotationally fixed manner, the driver (28) engaging into a thread-like guide path (31) of the eccentric bush (23) which is rotatably supported on the eccentric shaft (15), or

   B. the adjusting mechanism (24) is arranged between the rotatingly drivable eccentric shaft (15) in the screed (3) and an eccentric bush (23) which is arranged on the eccentric shaft (15) in a rotationally fixed manner and is displaceable in a direction transverse to the axis of the eccentric shaft (15) and is rotatable in a connecting rod (21) driving the tamper bar (14), in such a manner that the stroke (H) is adjustable by a transverse displacement of the eccentric bush (23) relative to the eccentric shaft (15), or

   C. the adjusting mechanism (24) is arranged between a bearing block (16') supporting the rotatingly driven eccentric shaft (15) and an adjusting lever (50) which is articulated to a connecting rod (21) driving the tamper bar (14) and is adjustable in the bearing block (16'), the adjusting lever (50) and the one push rod (48) drivable by the eccentric shaft (15) being coupled with the connecting rod (21) in a joint articulation axis (49), and wherein the bearing block (16') has a straight or arcuate guide path (52) which is engaged by an adjusting-lever pivot abutment (51) which is movable by means of the adjusting mechanism (24) along the guide path (52), and that the direction of extension of the guide path oriented in a direction transverse to the eccentric shaft (15) is at least approximately oriented towards the axis of the eccentric shaft (15).
2. The screed according to claim 1, characterized in that the control system (25) comprises at least one characteristic curve depending on paving parameters for automatically adjusting the stroke (H) in response to the paving parameters, and the control system (25) comprises a characteristic map depending on paving parameters for automatically adjusting the stroke (H) and the frequency (F) of the work cycles of the compaction unit in response to paving parameters.
3. The screed according to claim 1, characterized in that an axially electrically and/or hydraulically and/or mechanically, movable adjusting mechanism (33) is arranged in a rotationally fixed manner in the eccentric shaft (15), the adjusting mechanism (33) comprising a rotary type step switching mechanism (35, 36, 34, 37) cooperating with the eccentric bush (23) that is rotatably supported on the eccentric shaft (15).
4. The screed according to claim 1, characterized in that the eccentric shaft (15) and the eccentric bush (23) rotatably arranged on the eccentric shaft (32) have provided thereinbetween a clamping mechanism (39, 42) which couples the eccentric bush (23) in a force-fit and/or friction-fit and/or form-fit manner in a rotationally fixed way with the eccentric shaft (15) and that the clamping mechanism is temporarily movable into a release position by an axial release mechanism (41) which is supported in the screed (3), in which release position the coupling between the eccentric shaft (15) and the eccentric bush (23) is decoupled and the eccentric shaft (15) and the eccentric bush (23) are rotatable relative to each other.
5. The screed according to claim 1, characterized in that the eccentric shaft (15) and the transversely adjustable eccentric bush (23), which is coupled with the eccentric shaft (15) in a rotationally fixed manner, have provided thereinbetween guide blocks (44) which are adjustable in a direction transverse to the eccentric shaft (15) by means of at least one control rod (46, 46') which is guided in the eccentric shaft (15) in an axially shiftable manner and which are each equipped with an inclined guide surface (45, 47').
6. The screed according to claim 5, characterized in that the inclined guide surface (45 and 47', respectively) abuts in an axially movable manner on an inclined ramp (47, 47') either in the eccentric bush (23) or on the control rod (46, 46').
7. The screed according to claim 1, characterized in that the guide path (52) is arranged in relation to the axis of the eccentric shaft (15) and the articulation axis (49) on the connection rod (21) in such a manner that a lower dead center of the work cycle of the tamper bar (14) connected to the connecting rod (21) remains stationary independently of the adjustment of the pivot abutment (51) of the adjusting lever (50) along the guide path (52) in relation to a sole plate (18) mounted on a frame (17) of the screed (3) that is carrying the bearing block (16').
8. The screed according to claim 1, characterized in that a setting angle (α) and/or pavement thickness (S) respectively varying over the pave width of the screed (3) in transverse direction is/are sensed and at least the stroke (H) can be adapted individually over the pave width to the transverse variation of the setting angle (α) and/or the pavement thickness (S).
9. A road paver (1) comprising at least one screed (3) according to one of the previous claims mounted on traction bars (8), characterized in that said traction bars (8) being articulated to the road paver and the articulation points (9) thereof being vertically adjustable with leveling cylinders (10), wherein a computerized control system (25) is provided for automatically adjusting at least the stroke (H) of the tamper (14) in response to at least one paving parameter by means of control variables generated by the control system (25) and implemented by actuators, wherein the stroke (H) of the compaction unit (13) is automatically by means of the control unit (25) adjustable during the ongoing paving work in response to detected changes of at least the paving speed (V) and/or the pavement thickness (S), in such a manner that the precompaction in the pavement (6) is constant at least substantially independently of changes in the pavement thickness (S) and/or the paving speed (V).
10. The road paver according to claim 9, characterized in that sensors (29, 37, 30), preferably a plurality of sensors distributed in or transverse to the paving travel direction, are provided on the road paver (1) and/or the screed (3) and/or the bars (8) for sensing actual paving parameters, such as the setting angle (α) of the screed (3), and are coupled with the control system (25).
11. The road paver according to claim 9, characterized in that on the road paver (1) and/or the screed (3) an input and display section (27) is provided on the control system (25) or on a machine controller coupled with the control system (25) for additionally or alternatively setting control variables for at least the stroke (H) and/or the frequency (F), preferably also the setting angle (α).

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