Patent Publication Number: US-2022220675-A1

Title: Tamper stroke adjustment

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims foreign priority benefits under 35 U.S.C. § 119(a)-(d) to European patent application number EP 21151610.9, filed Jan. 14, 2021, which is incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to a road finishing machine and to a method for a continuous tamper stroke adjustment at a road finishing machine. 
     BACKGROUND 
     EP 3 138 961 B1 discloses a road finishing machine whose screed includes a tamper stroke adjusting means. The tamper stroke adjusting means has an adjusting transmission provided between a rotationally driveable eccentric shaft and an eccentric bushing rotatably mounted on the eccentric shaft. The stroke of the tamper bar is set by rotating the eccentric bushing on the eccentric shaft. EP 3 138 961 B1 moreover discloses an adjusting transmission which is provided between the rotationally driveable eccentric shaft and an eccentric bushing mounted on the eccentric shaft in a torque-proof manner, wherein for adjusting the tamper stroke of the tamper bar, the eccentric bushing is shifted over the adjusting transmission transversely to the eccentric shaft. EP 3 138 961 B1 finally discloses an adjusting transmission which includes a toggle mechanism. 
     In the two first-mentioned solutions above, the eccentric stroke adjustment during the operation of the road finishing machine is a technical challenge. This is in particular due to the fact that an activation or actuation of the adjusting transmission directly mounted on the eccentric shaft between the eccentric bushing and the eccentric shaft is difficult to carry out. The toggle mechanism is constructively rather complex and occupies a lot of space at the screed. 
     U.S. Pat. No. 8,371,770 B1 discloses a screed with a tamper stroke adjusting means including a threaded rod and a threaded bushing movably mounted thereon. An axial adjustment of the threaded bushing along the threaded rod moves a lever arm mounted at the threaded bushing, the tamper stroke setting at the screed of the road finishing machine depending on the position and orientation of said lever arm. 
     EP 1 905 899 A2 discloses a screed for a road finishing machine on which a tamper stroke adjusting means is mounted. The tamper stroke adjusting means comprises a bearing support for an eccentric shaft mounted horizontally and movable along a guiding slide on which an eccentric bushing is mounted in a torque-proof manner. By a horizontal displacement of the bearing support, a distance between the eccentric shaft mounted thereon and a tilting axle provided on the screed can be adjusted manually whereby a tamper stroke adjustment is effected. 
     EP 2 599 918 A1 discloses a method and a device for setting an upper dead center of a stamper bar of a road finishing machine. EP 2 599 919 A1 discloses a further device for a stroke adjustment of a stamper bar of a road finishing machine. 
     SUMMARY 
     It is an object of the disclosure to provide a road finishing machine with a tamper stroke adjusting means and a method for a continuous tamper stroke adjustment at a road finishing machine whereby the tamper stroke can be set, by means of simple, constructive technical means, in particular using fewer modules, precisely and continuously variably, mainly during the paving operation of the road finishing machine. 
     The disclosure relates to a road finishing machine with a screed for producing a paving layer, wherein the screed includes at least one compacting unit for precompacting paving material supplied to the screed, and wherein the compacting unit includes at least one eccentric bushing mounted on an eccentric shaft supporting the same to be rotatable at a desired angle of rotation to thereby continuously variably set a desired tamper stroke of a tamper bar of the compacting unit. 
     According to the disclosure, an adjusting mechanism mounted spaced apart from the eccentric shaft and at least partially rotating along with a rotary motion of the eccentric shaft is activatable for rotating the eccentric bushing with respect to the eccentric shaft. Since in the disclosure, a self-rotating adjusting mechanism activates, despite its spaced-apart position to the eccentric shaft, the eccentric bushing rotating along on the eccentric shaft for a tamper stroke adjustment, a plurality of advantages result altogether, as will be described below. 
     The rotation of the eccentric bushing on the eccentric shaft, that means the respective eccentricities of these two components, leads to a phase adjustment by which the desired tamper stroke can be set at the screed. The phase adjustment can be advantageously activated, in particular with low expenditure of force, by means of the adjusting mechanism spaced apart from the eccentric shaft and mainly rotating along itself at the speed of the eccentric shaft. To set the phase adjustment between the eccentric bushing and the eccentric shaft, the adjusting mechanism rotating along can at least temporarily be activated such that the torque driving it at its input side or the speed applied there at its output side, where it provides a coupling to the eccentric bushing, is geared up or down. Thereby, the eccentric bushing coupled to the adjusting mechanism and rotating along on the eccentric shaft can be “slowed down” or “accelerated” corresponding to the transmission ratio activated by means of the adjusting mechanism relative to the rotary motion of the eccentric shaft, whereby the eccentric bushing rotates to a new angular position relative to the eccentric shaft, i.e., performs the phase adjustment activated by means of the adjusting mechanism. Without a separate activation of the adjusting mechanism rotating along, the eccentric bushing rotates at the same speed as the eccentric shaft, i.e., together with it with a constant phase angle. 
     The term “rotating along” means that the adjusting mechanism or at least a portion of the components provided thereon rotates together with the eccentric shaft, however mounted at a distance thereto, during the operation of the compacting unit. This module rotating along with the eccentric shaft can be activated sensitively, with low expenditure of force for the above-described phase adjustment, that means a change of the angular position of the eccentric bushing positioned on the eccentric shaft, i.e., for varying the tamper stroke. Moreover, the activation of the adjusting mechanism positioned spaced apart from the eccentric shaft can be carried out more precisely. Furthermore, by means of such an adjusting mechanism rotating along, the tamper stroke adjustment can be carried out better in an automated way. 
     In particular, a power flow branched off from the eccentric shaft itself to the adjusting mechanism for the relative rotation of the eccentric bushing to the eccentric shaft and at least partially causing it to rotate in response to a rotary motion of the eccentric shaft may be present, wherein the adjusting mechanism caused to rotate thereby can be activated such that it manipulates the power flow directed to it between its input and its output such that it results in a phase shift at its output based on which the eccentric bushing is accordingly rotated on the eccentric shaft. The adjusting mechanism can be present, for example, as a hydraulic and/or electromechanical phase adjusting system. 
     In the disclosure, the desired tamper stroke adjustment is preferably accomplished as a sum of the individual eccentricities of the eccentric shaft and the eccentric bushing rotatably mounted thereon. A phase angle adjusted therebetween can be changed in a quickly responding and very precise manner by means of the adjusting mechanism rotating along, in particular if it is embodied as an electromechanical phase adjuster. As a rotating module, the adjusting mechanism can be excellently activated for a phase adjustment between its input and output ends. 
     The adjusting mechanism employed in the disclosure is as such based, advantageously in a compact manner, on already existing components or modules of the screed, so that thereby, a high degree of equal parts is possible even at different screed types. Due to its position spaced apart from the eccentric shaft, the eccentric shaft itself can be of a simpler design in view of construction. 
     As in the disclosure, the adjusting mechanism can preferably be at least partially rotationally driven by the eccentric shaft, an advantageous balance of forces altogether results for the phase adjustment that can be set at it for adjusting the tamper stroke. This in turn leads to the fact that the adjusting mechanism can be easily automated, whereby a better paving result by means of the road finishing machine is possible 
     Preferably, the adjusting mechanism comprises at least one adjusting drive that can be activated for rotating the eccentric bushing and which is rotationally driven as such by means of the rotary motion of the eccentric shaft, and/or at least one adjusting transmission that can be activated for rotating the eccentric bushing and is rotationally driven by means of the rotary motion of the eccentric shaft. The rotary motion of the eccentric shaft is in this embodiment in general the reason for the rotation of the adjusting drive and/or the adjusting transmission. In this variant, the adjusting drive and/or the adjusting transmission is integrated in a drive train branched off from the eccentric shaft in the power flow of which the adjusting drive and/or the adjusting transmission is integrated to rotate along. A sensitive varying of the angle of rotation between the eccentric bushing and the eccentric shaft is here achieved by an actuation of the adjusting drive and/or the adjusting transmission already with low expenditure of force. In particular, the phase shift angle of the adjusting drive and/or adjusting transmission rotating along in the power flow can be more easily adjusted thereby. By this, the adjusting mechanism is better able to rotate the eccentric bushing with respect to the eccentric shaft into any desired tamper stroke adjustment while the paving operation is in progress, i.e., to adjust the tamper stroke between a minimal and a maximal tamper stroke value. 
     For a compact construction, it is advantageous for the adjusting drive and the adjusting transmission to form a function unit rotating along together. The function unit is then present as a modular phase adjuster which is mounted to rotate along with the speed of the eccentric shaft with respect to it, wherein the adjusting drive can activate the adjusting transmission for a desired phase adjustment so that in response thereto, the eccentric bushing rotates with respect to the eccentric shaft in order to vary the tamper stroke. 
     As has been described above, in the disclosure, the rotating eccentric shaft can be present with the function of an actuator for the adjusting drive rotating along and coupled thereto and/or the adjusting transmission rotating along, wherein for performing the phase adjustment between the eccentric bushing and the eccentric shaft, the adjusting drive rotating along and/or the adjusting transmission rotating along as such is, apart from its rotation, additionally activatable. The torque picked off by the eccentric shaft can be at least temporarily changed in the drive train branched off from the eccentric shaft by means of the adjusting drive and/or the adjusting transmission rotatably driven therein for setting the desired phase shift angle, so that forces resulting therefrom slow down or accelerate, that means rotate, the eccentric bushing on the eccentric shaft. 
     By the fact that in the disclosure, the eccentric shaft preferably both serves for driving the tamper bar and can be present for the function of a drive shaft for the adjusting drive rotating along and/or the adjusting transmission rotating along, that it so to speak fulfills a double function, an adjusting force optionally exerted from outside onto the adjusting drive and/or the adjusting transmission for rotating the eccentric bushing can be considerably reduced. Thereby, the components employed for the tamper stroke adjustment can also be constructively reduced, whereby manufacturing costs can be reduced. 
     The torque continuously picked off, preferably by the eccentric shaft, during the paving operation can be manipulated in the branched-off power flow by means of the adjusting drive rotating along and arranged therein and/or the adjusting transmission rotating along such that, without any high additional introduction of force, an adjusting movement of the eccentric bushing on the eccentric shaft rotating by means of the drive speed is easily possible. An adjusting moment for varying the tamper stroke, that means for changing a vectorial sum of the individual eccentricities of the eccentric bushing and the eccentric shaft, result from the phase adjustment that can be activated by means of the adjusting drive and/or the adjusting transmission. During the performance of the phase adjustment, the eccentric bushing is rotated relatively to the rotary motion of the eccentric shaft into or against a sense of rotation of the eccentric shaft until the eccentric bushing assumes a desired angular position on the eccentric shaft adjusted with respect to its starting position. 
     Preferably, the adjusting drive rotating along and/or the adjusting transmission rotating along is activatable to adjust an angle of rotation of a machine element rotatably mounted on the eccentric shaft. The machine element permits a constructively easily producible coupling of the adjusting drive and/or the adjusting transmission with the eccentric bushing mounted on the eccentric shaft. The machine element can be present, for example, in the form of a gearwheel or a pulley for a synchronous belt. 
     In one embodiment, the machine element itself forms the eccentric bushing or is connected to the eccentric bushing by means of an interlocking clutch, for example by means of a claw clutch. The first mentioned alternative results in a construction with a reduced number of parts. The second alternative can be advantageous for service and/or maintenance measures. 
     For a standardized construction, it is advantageous for at least one further machine element to be provided which is embodied to transmit a rotary motion of the eccentric shaft to the adjusting drive and/or the adjusting transmission. The further machine element is preferably mounted on the eccentric shaft in a torque-proof manner. This is preferably a gearwheel or a pulley for a synchronous belt. For the further machine element, at the adjusting drive and/or at the adjusting transmission, for example on a transmission case of the adjusting transmission or on a housing of the adjusting drive, a complementary coupling member, for example in the form of a gearwheel or a pulley for the synchronous belt, can be mounted in a torque-proof manner. 
     By means of the further machine element, the transmission of movement or forces from the eccentric shaft to the adjusting mechanism can be performed. A separate activation, for example a hydraulic or electromechanical activation, of the adjusting mechanism caused to rotate, in particular the adjusting drive rotating along and/or the adjusting transmission rotating along, causes the first machine element coupled to its output end and rotatably arranged on the eccentric shaft—and thus also the eccentric bushing—to be phase-adjusted. As soon as the first machine element has assumed the desired angular position, i.e., the desired tamper stroke is set, the above-mentioned separate activation of the rotationally driven adjusting mechanism is stopped. An actual angle of rotation between the eccentric bushing and the eccentric shaft adjusted thereby at the compacting unit is then easily detectable by means of an appropriate sensory mechanism. The adjusting mechanism continuously rotating along during the operation of the compacting unit can be activated again for a subsequently desired phase adjustment, so that a new switching moment occurs at its output end coupled to the eccentric bushing with respect to its input end. 
     The above-described machine elements for coupling the eccentric shaft with the adjusting mechanism and for coupling the same with the eccentric bushing can be present as a gearwheel, a pulley and/or a chain wheel and thus form standardized, above all inexpensive machine components. 
     It offers itself, although this is not obligatory, that during an operation of the compacting unit, the adjusting drive and/or the adjusting transmission is rotationally driven at the same speed as the eccentric shaft. For example, equally dimensioned gear/chain wheels or pulleys are employed for this in the drive train between the eccentric shaft and the adjusting mechanism rotationally driven thereby. In particular, during an operation of the compacting unit, the adjusting drive and/or the adjusting transmission can have a different speed from that of the eccentric shaft. A desired tamper stroke can be achieved in that the same transmission is present between the eccentric shaft and the adjusting transmission and between the adjusting transmission and the eccentric bushing. In other words, the eccentric shaft and the adjusting shaft on which the adjusting transmission is mounted can have different speeds; the eccentric shaft and the eccentric bushing not. 
     It is advantageous for the adjusting drive and/or the adjusting transmission to be actuated hydraulically, electrically and/or mechanically. By means of a hydraulic adjusting drive and/or adjusting transmission, above all, high adjusting forces could be generated. An electrical or electromechanical adjusting mechanism would permit the tamper stroke adjustment within shorter reaction times, that means independent of a hydraulic temperature. 
     Preferably, the adjusting transmission is a continuously variable mechanical, hydrostatic or electric transmission. Preferably, the adjusting transmission is activatable for setting a desired transmission ratio by means of a mechanical, hydraulic or electric drive anyway present at the screed, i.e., by means of a drive which is furthermore employed for the operation of another working component of the screed. This further contributes to a reduction of the employed components or modules. 
     In a variant, the adjusting drive includes an activatable servomotor, and/or a servomotor is provided for the adjusting transmission. The servomotor can form, together with the adjusting transmission, a function unit rotating along with the eccentric shaft, wherein the servomotor is activatable for the desired phase adjustment such that it changes the power flow transmitted to the eccentric bushing via the adjusting mechanism rotating along by the adjusting transmission connected thereto. In response thereto, the eccentric bushing rotates on the eccentric shaft into the desired angular position. 
     Preferably, the adjusting transmission is embodied as a cam mechanism and/or includes a pair of rotating deflection rollers. By this, the adjusting transmission can be embodied to be particularly robust. It is conceivable for the cam mechanism to comprise two cam disks mounted to be adjustable with respect to each other and which can be displaced linearly and/or rotationally with respect to each other. A movement of the cam disks with respect to each other can cause an adjustment of the deflection rollers mounted thereon along cam paths embodied thereon resulting in a phase adjustment. 
     According to one embodiment of the disclosure, the adjusting transmission provides, for shifting the deflection rollers mounted thereon and rotating along in the power flow, at least one stationarily mounted cam disk. This is mounted at the stationary cam disk for a translatory and/or rotatory displacement to thereby adjust a shifting of the axes of rotation of the deflection rollers rotating along for a phase adjustment. 
     According to one embodiment, the pair of rotating deflection rollers is mounted, for rotating the eccentric bushing on the eccentric shaft, to be shifted transversely to the eccentric shaft, i.e., transversely to its axis of rotation. The deflection rollers rotating along can be mounted abutting against a sprocket belt or a drive chain which is connected with the machine element rotationally mounted on the eccentric shaft. By means of a displacement of the deflection rollers, a length ratio of the belt or chain sections guided oppositely simultaneously changes, so that in response thereto, the machine element on the eccentric shaft rotates, that means the eccentric bushing is phase-adjusted with respect to the eccentric shaft. 
     The two deflection rollers rotating along can be rotationally mounted with respect to axes of rotation mounted in parallel and spaced apart from each other. By means of a change of the positioning of the deflection rollers rotating along, in particular a change of the distance between the axes of rotation, an influence can be exerted on the phase adjustment angle by means of which the eccentric bushing lies on the eccentric shaft. 
     Preferably, a translatory shifting of the deflection rollers rotating along transverse to the axis of rotation of the eccentric shaft on one side of the synchronous belt guided around the deflection rollers or the drive chain leads to an extension of the path which is simultaneously compensated by a shortening of the path on the opposite side of the synchronous belt or the drive chain. Thereby, with low expenditure of force, a rotation of the eccentric bushing on the eccentric shaft can be effected, so that the eccentric bushing assumes a desired angle of rotation on the eccentric shaft for setting the tamper stroke. 
     In an advantageous variant, the adjusting drive and/or the adjusting transmission is embodied for synchronously adjusting a plurality of eccentric bushings rotationally mounted along the eccentric shaft (overall stroke adjustment), or the adjusting mechanism comprises a plurality of adjusting drives and/or adjusting transmissions for separately adjusting a plurality of eccentric bushings rotationally mounted along the eccentric shaft (individual stroke adjustment). The eccentric bushings installed along a plurality of unit sections can in these variants be adjusted together, that means synchronously with each other, or independently, i.e., individually. By means of independently activatable eccentric bushings, different tamper strokes could be set during a pavement drive via the paving width producible by the screed. 
     For a synchronous adjustment of the eccentric bushings, the adjusting mechanism can be coupled to an adjusting shaft at its output end. The adjusting shaft can transmit a phase adjustment centrically set by means of the adjusting mechanism synchronously to a plurality of unit sections of the compacting unit, i.e., to eccentric bushings mounted thereon. As an alternative, for each unit section of the compacting unit, an independently activatable adjusting mechanism rotating along can be present. These can be mounted on a common shaft by which they take up one rotary motion of the eccentric shaft each. At its output end, however, different phase adjustments can be adjusted. Preferably, the adjusting shaft or the shaft is mounted in parallel to the eccentric shaft. 
     According to one embodiment, the adjusting drive and/or the adjusting transmission is activatable for setting the desired angle of rotation of the eccentric bushing by means of a controlling system. The controlling system can be present as an integral part of the adjusting mechanism independent of whether it is employed for an overall stroke adjustment or an individual stroke adjustment. The controlling system can be connected to a vehicle control of the road finishing machine via a CAN-bus system by which the desired tamper stroke or the respective desired tamper strokes can be stored. 
     In a particularly preferred variant, the controlling system includes, for a dynamic adaption of the angle of rotation of the eccentric bushing, at least one control loop responding to at least one process parameter detectable during the operation of the road finishing machine. By means of the control loop, for example, one can correspondingly respond to a measured material-specific value of the paving material to be installed, for example to a measured temperature of the paving material transported from the material bunker of the road finishing machine to the screed, and/or the produced paving layer, for example to a measured temperature of the paving layer, with an adaption of the angle of rotation between the eccentric bushing and the eccentric shaft to create an optimal paving result. 
     In one preferred embodiment of the disclosure, the control loop is able to control a dynamic adjustment of the angle of rotation between the eccentric bushing and the eccentric shaft in reaction to a disturbance variable, for example an ambient temperature, for continuously adapting the tamper stroke. 
     It is conceivable that during the adjustment of the tamper stroke, a set angle of attack of the screed, a paving travel speed of the road finishing machine, a set drive speed of the eccentric shaft, a temperature of compacting plates of the screed and/or measured values of a separate construction vehicle, for example measured values with respect to the produced paving layer which are detected by means of a compacting vehicle driving behind the road finishing machine, are considered. 
     Preferably, the adjusting mechanism comprises at least one sensor unit embodied for detecting a set phase angle between the eccentric bushing and the eccentric shaft supporting the same and/or for detecting a stroke of the tamper bar. It is conceivable that the adjusting drive comprises at least one sensory unit suitable for this, for example one or more angle sensors, above all when it is present as a servomotor. By this, on the basis of the detected angular position of the motor shaft of the servomotor, the phase adjustment between the eccentric bushing and the eccentric shaft can be derived. By means of the detected phase adjustment, the controlling system can calculate the actual tamper stroke. It is conceivable that the controlling system derives the corresponding actual tamper stroke based on the measured phase adjustment, for example by means of phase characteristics. A phase adjustment detected or varying by means of the sensor unit can be transmitted to the control unit in real time so that it optionally outputs a corresponding control signal to the adjusting drive, in particular the servomotor, based on a comparison of a desired and an actual tamper stroke, to activate a rotation of the eccentric bushing for a tamper stroke adaption by quick response. 
     The sensor unit could, according to one embodiment, include at least one distance sensor which is embodied to directly measure a set actual tamper stroke of the tamper bar. 
     In one practical variant, the adjusting mechanism is embodied to be manually adjustable. This can be helpful, above all, for a calibration of the tamper bar at the beginning of the pavement drive. In contrast, an automated operation of the adjusting mechanism can be perfectly employed during the pavement drive. 
     The disclosure also relates to a method for a continuously variable tamper stroke adjustment at a compacting unit of a road finishing machine, wherein for adjusting the tamper stroke, at least one eccentric bushing is rotated on an eccentric shaft supporting it. According to the disclosure, for rotating the eccentric bushing on the eccentric shaft, an adjusting mechanism mounted to be spaced apart from the eccentric shaft and at least partially rotating along with a rotary motion of the eccentric shaft is activated. 
     Preferably, the relative rotation between the eccentric bushing and the eccentric shaft results by a power flow derived from the eccentric shaft and causing a rotational movement of the adjusting mechanism or at least parts thereof being at least temporarily geared up or down by means of the adjusting mechanism such that the angle of rotation between the eccentric bushing and the eccentric shaft is changed thereby. That means, here, the torque is derived from the eccentric shaft and transmitted to the adjusting mechanism as a driving torque. In particular an adjusting transmission connected thereto and also rotating along can be activated by means of an adjusting drive for a torque adaption. In this embodiment, the eccentric bushing uniformly, i.e., at the same speed, rotates along on the eccentric shaft without an additional activation of the adjusting drive. By means of a separate activation of the adjusting drive, the adjusting transmission coupled thereto can create a difference velocity between the eccentric bushing and the eccentric shaft bearing it, whereby the eccentric bushing is rotated into a new angular position on the eccentric shaft. By this, the tamper stroke is adjusted. Thereby, the compacting unit can do altogether with a reduced number of mechanical, electric and/or hydraulic components to vary the tamper stroke. Thereby, a practical, inexpensively producible and essentially autonomously operating adjusting means for varying the tamper stroke at the road finishing machine results. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Advantageous embodiments of the disclosure will be illustrated more in detail with reference to the following figures. 
         FIG. 1  shows a schematic side view of a road finishing machine; 
         FIG. 2  shows a compacting unit for a screed of a road finishing machine according to a first embodiment; 
         FIG. 2A  shows a first operating state of the compacting unit shown in  FIG. 2 ; 
         FIG. 2B  shows a second operating state of the compacting unit shown in  FIG. 2 ; 
         FIG. 2C  shows a variant of the first embodiment shown in  FIG. 2  for an overall stroke adjustment; 
         FIG. 2D  shows a variant of the embodiment shown in  FIG. 2  for an individual stroke adjustment; 
         FIG. 3  shows a compacting unit for a screed of a road finishing machine according to a second embodiment; 
         FIG. 3A  shows a sectional representation of the adjusting mechanism of the second embodiment shown in  FIG. 3 ; 
         FIG. 3B  shows a separate representation of the adjusting mechanism of the embodiment shown in  FIG. 3 ; 
         FIG. 3C  shows a variant of the second embodiment shown in  FIG. 3  for an overall stroke adjustment; and 
         FIG. 3D  shows a schematic representation of the second embodiment of  FIG. 3  for an individual stroke adjustment. 
     
    
    
     Equal components are always provided with equal reference numerals in the figures. 
     DETAILED DESCRIPTION 
       FIG. 1  shows a road finishing machine  1  with a screed  2  for producing a paving layer  3  in the paving travel direction R. The screed  2  has at least one compacting unit  4  for precompacting a paving material  5  supplied to the screed  2 . The compacting unit  4  includes a tamper bar  6  which can be driven with a variable tamper stroke H and/or a variable frequency F for precompacting the paving material  5  supplied to the screed  2 . 
       FIG. 2  shows the compacting unit  4  separately in an enlarged perspective representation. The compacting unit  4  has a bearing support  7  fixed to the screed body and an eccentric shaft  8  rotationally mounted thereto. The eccentric shaft  8  drives a connecting rod  9  to which the tamper bar  6  is fixed. 
       FIG. 2  furthermore shows an adjusting mechanism  10  which is rotationally driven by means of the eccentric shaft  8 . The adjusting mechanism  10  can be activated to set a variable desired tamper stroke  11  for the tamper bar  6 . To this end, the adjusting mechanism  10  rotating along comprises an adjusting drive  12  and/or an adjusting transmission  13 . According to  FIG. 2 , the adjusting drive  12  and the adjusting transmission  13  are embodied as a function unit. This function unit is coupled to a rotary motion of the eccentric shaft  8  by means of a synchronous belt  14 . 
     The adjusting mechanism  10  can, without being additionally activated, return the torque, which drives by means of the synchronous belt  14  at its input end and causes it to rotate, to a machine element  16  rotationally mounted on the eccentric shaft  8  by means of a further synchronous belt  15  provided at its output end. By an additional activation of the adjusting mechanism  10 , a phase angle of the machine element  16  mounted on the eccentric shaft  8  can be changed. By means of this phase adjustment, an eccentric bushing  17  (see  FIG. 2C ) rotationally mounted within the connecting rod  9  on the eccentric shaft  8  and coupled to the machine element  16  can be adjusted. According to  FIG. 2 , for rotating the eccentric bushing  17  on the eccentric shaft  8 , the adjusting mechanism  10  mounted spaced apart from the eccentric shaft  8  and rotating along with the rotary motion of the eccentric shaft  8  can be activated. 
     With reference to  FIGS. 2A and 2B , the performance of a phase adjustment by means of the adjusting mechanism  10  to adjust the tamper stroke  11  is schematically shown. 
     In  FIG. 2A , the synchronous belt  14 , which is guided on a pulley  18  mounted on the eccentric shaft  8  in a torque-proof manner, transmits the rotary motion of the eccentric shaft  8  to a housing  19  of the adjusting mechanism  10 . The housing  19  can be embodied with a diameter as that of the pulley  18 . Thereby, between the eccentric shaft  8  and the adjusting mechanism  10 , a belt drive is created which takes care that the adjusting mechanism  10  rotates at the speed of the eccentric shaft  8 . 
     In  FIG. 2A , the adjusting mechanism  10  rotating along is not additionally activated, so that a torque applied to its housing  19  at its input end is forwarded to the machine element  16  via the further synchronous belt  15  fixed to its output end. According to  FIG. 2A , the consequence of this is that the eccentric bushing  17  mounted within the connecting rod  9  rotates at the speed of the eccentric shaft  8 , that means it maintains its angular position with respect to the eccentric shaft  8 .  FIG. 2A  shows this situation schematically by means of the two markings A, B running equally. 
     In  FIG. 2B , the adjusting mechanism  10  has performed a phase adjustment  26  with respect to  FIG. 2A . This is shown by means of the two markings A, B now represented shifted with respect to each other. In response thereto, the machine element  16  has rotated with respect to the position shown in  FIG. 2A  on the eccentric shaft  8  corresponding to the phase adjustment  26 . This causes the eccentric bushing  17  coupled to the machine element  16  to also assume an angular position on the eccentric shaft  8  changed by the phase adjustment  26 , so that this results, together with the eccentricity of the eccentric shaft  8 , in a new desired tamper stroke  11 . 
       FIG. 2C  shows a first variant of the embodiment shown in  FIG. 2  for an overall stroke adjustment at the compacting unit  4 . This means that a plurality of eccentric bushings  17  positioned along the eccentric shaft  8  are synchronously rotatable by means of the adjusting mechanism  10 . 
     In  FIG. 2C , the eccentric shaft  8  is driven by a motor  20 . The belt drives represented in  FIG. 2  for coupling the eccentric shaft  8  with the adjusting mechanism  10  and for coupling the adjusting mechanism  10  with the machine element  16  are replaced by drive wheels  21 ,  22  and adjusting wheels  23 ,  24  in  FIGS. 2C and 2D . The drive wheel  21  is mounted on the eccentric shaft  8  in a torque-proof manner. The drive wheel  22  is seated on the housing  19  of the adjusting mechanism  10  in a torque-proof manner. The adjusting mechanism  10  is mounted on a shaft  25  in a torque-proof manner. The adjusting mechanism  10  is configured to perform the phase adjustment  26  between the drive wheel  22  mounted on its housing  19  and the adjusting wheel  23  mounted at its output end. The phase adjustment  26  performed by means of the adjusting mechanism  10  is transmitted from the adjusting wheel  23  to the adjusting wheel  24  and the machine element  16 . According to  FIG. 2C , the adjusting wheel  24  and the machine element  16  are integrally formed. By means of a rotation of the machine element  16 , the eccentric bushing connected thereto by means of a claw clutch  27  in  FIG. 2C  is rotated on the eccentric shaft  18 . Thereby, a change of the (desired) tamper stroke  11  of the tamper bar  6  occurs. 
     In  FIG. 2C , the adjusting mechanism  10  has a sensor unit  28  which is configured to detect the phase adjustment  26  and thus also the angular position of the eccentric bushing  17  on the eccentric shaft  8 . The sensor unit  28  transmits its measuring results continuously to a controlling system  29  connected thereto. The controlling system  29  can store the desired tamper stroke  11 , the controlling system  29  being configured to calculate an actual tamper stroke from the measured phase adjustment  26  and compare it with the stored desired tamper stroke  11 , based on which the controlling system  29  emits a control signal  30  to the adjusting drive  12  of the adjusting mechanism  10 . The adjusting drive  12 , for example a synchronous motor M rotating along, can then adapt the phase adjustment  26  based on the control signal  20 . 
     The controlling system  29  can include a control loop RK which responds to a process parameter P measured during the operation of the road finishing machine  1 , based on which a dynamic adaption of the angle of rotation, that means a dynamic phase adjustment  26 , for varying the tamper stroke  11  is possible. The functional principle of the controlling system  29  and/or of the control loop RK is also applicable in connection with all following embodiments. 
       FIG. 2C  furthermore shows that the adjusting mechanism  10  has an adjusting shaft  31  at its output end. According to  FIG. 2C , the adjusting wheel  23  is mounted on the adjusting shaft  31  in a torque-proof manner. By this it is possible to transmit the phase adjustment  26  set by means of the adjusting mechanism  10  in  FIG. 2C  via the adjusting shaft  31  synchronously to another unit section  32 . By means of further adjusting wheels  33 ,  34 , an eccentric bushing not shown at the unit section  32  is rotated there analogously synchronously to the eccentric bushing  17 . 
       FIG. 2C  thus shows that the adjusting mechanism  10  is embodied, via the adjusting shaft  31 , for synchronously adjusting a plurality of eccentric bushings  17  rotationally mounted along the eccentric shaft  8 . 
       FIG. 2D  shows a device that is embodied for separately adjusting a plurality of eccentric bushings  17  rotationally mounted along the eccentric shaft  8 . By means of this device, an individual stroke adjustment is thus possible. 
     According to  FIG. 2D , the compacting unit  4  comprises the adjusting mechanism  10  for varying the desired tamper stroke  11  of the tamper bar  6 , and furthermore an additional adjusting mechanism  10 ′ for the further unit section  32 . The adjusting mechanism  10 ′ is driven via the shaft  25  and has a sensor unit  28 ′ by means of which a phase adjustment  26 ′ set at the unit section  32  can be measured on the basis of which the eccentric bushing  17 ′ mounted at the unit section  32  is rotated on the eccentric shaft  8 . For an independent actuation of the two adjusting wheels  23 ,  33 , these are rotationally mounted on the shaft  25 . It is thus possible to adjust, at the respective unit sections of the compacting unit  4 , the desired tamper stroke  11 ,  11 ′ for the respective tamper bars  6 ,  6 ′ independently with respect to each other. 
       FIG. 3  shows a second embodiment of the compacting unit  4 . The compacting unit  4  furthermore has an adjusting mechanism  35 . The adjusting mechanism  35  can be activated to rotate the machine element  16  rotationally mounted on the eccentric shaft  8  such that the desired tamper stroke  11  can be adjusted at the tamper bar  6 . 
     The adjusting mechanism  35  of  FIG. 3  has a pair of deflection rollers  36   a ,  36   b  rotating along. The two deflection rollers  36   a ,  36   b  are mounted to be reciprocated transversely to the eccentric shaft  8  which is shown by the double arrows v 1 , v 2 . The adjusting mechanism  35  is connected to the rotary motion of the eccentric shaft  8  by means of drive disks  37 ,  38 ,  39  mounted in a torque-proof manner by means of synchronous belts  40 ,  41  guided thereon. The drive disks  38 ,  39  separately represented in  FIG. 3  could also be embodied as one component. A displacement of the two deflection rollers  36   a ,  36   b  transverse to the eccentric shaft  8  causes the machine element  16  connected to the adjusting mechanism  35  via the synchronous belt  41  to rotate on the eccentric shaft  8 . The eccentric bushing  17  fixed thereto thereby also changes its angular position on the eccentric shaft  8 , so that the (desired) tamper stroke  11  is adjusted. 
     The functional principle of the phase adjustment by means of the adjusting mechanism  35  is represented in greater detail in  FIG. 3A . In the left half of the picture of  FIG. 3A , the drive disk  39  and the machine element  16  are both mounted at an angle of rotation φ. For this, the adjusting mechanism  35  assumes a corresponding position according to  FIG. 3A . This positioning of the two deflection rollers  36   a ,  36   b  rotating along results in a minimal tamper stroke  11  for the tamper bar  6 . 
     In the right half of the picture of  FIG. 3A , the setting of the adjusting mechanism  35  is shown for a maximal tamper stroke  11  of the tamper bar  6 . In response to a displacement {right arrow over (R 1 , R 1 ′)}, {right arrow over (R 2 , R 2 ′)} of the two deflection rollers  36   a ,  36   b , a new angle of rotation φ resulted for the machine element  16 . The displacement of the two deflection rollers  36   a ,  36   b  rotating along transversely to the eccentric shaft  8  driving the same thereby causes the phase adjustment  26  of the machine element  16 , whereby the eccentric bushing  17  rotates on the eccentric shaft  8 . 
       FIG. 3B  shows a potential construction for the adjusting mechanism  35 . The adjusting mechanism  35  includes an adjustably mounted cam disk  42  with a first cam path  43  for the deflection roller  36   a  and with a second cam path  44  for the deflection roller  36   b . Furthermore, the adjusting mechanism  35  has a stationarily mounted cam disk  45  with a guide path  46  for the deflection rollers  36   a ,  36   b . By means of a displacement of the cam disk  42  in the direction E, the two deflection rollers  36   a ,  36   b  are shifted together in the direction E in the guide path  46 . By the displacement of the two deflection rollers  36   a ,  36   b , the phase adjustment  26  takes place at the machine element  16  whereby the eccentric bushing  17  rotates on the eccentric shaft  8 . 
     Furthermore,  FIG. 3B  shows a section A-A in its right picture half. The deflection roller  36   a  is mounted on a bolt  47 . To reduce a frictional resistance, the deflection roller  36   a  is fixed to the bolt  47  by means of a rolling bearing  48 . 
       FIGS. 3C and 3D  show variants of the adjusting mechanism  35 , the variant shown in  FIG. 3C  being configured to synchronously adjust a plurality of eccentric bushings  17  mounted along the eccentric shaft  8  (overall stroke adjustment), and the variant represented in  FIG. 3D  being configured for an individual stroke adjustment at respectively adjacent unit sections of the compacting unit  4 . 
     In  FIG. 3C , the adjusting mechanism  35  is mounted between the drive wheel  37  and an adjusting wheel  50 . A phase adjustment  26  set by means of the adjusting mechanism  35  in  FIG. 3C  acts on the adjusting wheel  50  via the synchronous belt  40 , wherein the adjusting shaft  31 ′ supporting the adjusting wheel  50  can transmit the torque to further unit sections of the compacting unit  4  synchronously to set eccentric bushings mounted there corresponding to the eccentric bushing  17  of  FIG. 3C . 
     In  FIG. 3C , the phase adjustment  26  set by means of the adjusting mechanism  35  is transmitted to the machine element  16  via the two adjusting wheels  50 ,  51  and the synchronous belt  41 , which machine element assumes a corresponding angle of rotation φ on the eccentric shaft  8 . The machine element  16  is connected to the eccentric bushing  17  via the claw clutch  27 . The phase adjustment  26  set at the machine element  16  is thereby transmitted to the eccentric bushing  17 , based on which the desired tamper stroke  11  can be set. 
     The schematic representation of  FIG. 3D  shows that the adjusting mechanism  35  is arranged according to  FIG. 3 , that means it can generate the phase adjustment  26  between the drive wheel  39  and the machine element  16 . According to  FIG. 3D , for each unit section of the compacting unit  4 , a separate adjusting mechanism  35  can be arranged, so that the respective tamper strokes  11  of the unit sections can be activated independently.