Abstract
The present invention relates to an attachment screed unit for a road paver, comprising a connecting screed, at least one adjusting screed which is adjustably mounted on the connecting screed and which is adjustable between a retracted position (P.sub.1) and an extended position (P.sub.2), as a result of which the paving width (b.sub.4) of the attachment screed unit can be set in a variable manner, and a hydraulic adjusting device, which is arranged in such a manner that it can adjust the at least one adjusting screed between the retracted position (P.sub.1) and the extended position (P.sub.2), the adjusting device comprising an electro-hydraulic unit which is arranged on the attachment screed unit (10), and the electric hydraulic unit comprising a separate hydraulic circuit with at least one hydraulic pump and an actuator. The present invention further relates to a road paver with such an attachment screed unit.
Claims
1. An attachment screed unit for attachment to a screed unit of a road paver, comprising: a connecting screed; at least one adjusting screed which is adjustably mounted on the connecting screed and which is adjustable between a retracted position (P.sub.1) and an extended position (P.sub.2) relative to the connecting screed, as a result of which the paving width (b.sub.4) of the attachment screed unit is variable; and a hydraulic adjusting device, which is arranged in such a manner that it can adjust the at least one adjusting screed between the retracted position (P.sub.1) and the extended position (P.sub.2), the adjusting device comprising an electro-hydraulic unit which is arranged on the attachment screed unit and comprises an electric connection via which the electro-hydraulic unit can be supplied with electric power, and the electro-hydraulic unit comprising a separate hydraulic circuit which is independent of, and not fluidly connected to, the hydraulic circuit of the road paver, with the hydraulic circuit being located entirely on the attachment screed, and with the electro-hydraulic unit having at least one electrically driven hydraulic pump and a hydraulic actuator which is driven by the hydraulic pump.
2. The attachment screed unit according to claim 1, wherein the electro-hydraulic unit comprises a power source.
3. The attachment screed unit according to claim 1, wherein the actuator is a linear drive.
4. The attachment screed unit according to claim 1, wherein the adjusting device is arranged in such a manner that it can continuously adjust the adjusting screed between the retracted position (P.sub.1) and the extended position (P.sub.2).
5. The attachment screed unit according to claim 1, wherein the attachment screed unit comprises an operator control device operable to allow an operator to set the paving width (b.sub.4) of the attachment screed unit.
6. The attachment screed unit (10) according to claim 1, wherein the connecting screed comprises on its face end an attachment device via which the attachment screed unit can be attached to a screed.
7. The attachment screed unit according to claim 6, wherein the attachment device comprises at least one fastening device on the face end of the connecting screed transversely to the working direction.
8. The attachment screed unit according to claim 7, wherein the fastening device comprises an engagement hook protruding beyond the face end.
9. The attachment screed unit according to claim 7, wherein the fastening device is a part of a quick-action connection that can be actuated mechanically.
10. A road paver having a screed unit and at least one attachment screed unit according to claim 1 which is mounted on the screed unit.
11. The road paver according to claim 10, wherein a respective attachment screed unit is directly arranged on each of the face ends of the screed unit situated opposite each other transversely to the working direction.
12. The road paver according to claim 10, wherein the at least one connecting screed of the attachment screed unit is connected to a rigid screed of the road paver via at least one intermediate screed.
13. The road paver according to claim 10, wherein a connection device is provided on the road paver via which an electric connection is provided for the connection of the attachment screed.
14. The attachment screed unit of claim 2, wherein the power source comprises a battery.
15. The attachment screed unit of claim 7, wherein the linear drive comprises a double-acting hydraulic cylinder or a rack-and-pinion drive.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The present invention will be explained below in closer detail by reference to the exemplary embodiments shown in the schematic drawings, in which:
(2) FIG. 1 shows a side view of a road paver;
(3) FIG. 2 shows a top view of a road paver having two attachment screed units according to a first embodiment;
(4) FIG. 3 shows a top view of a road paver having two attachment screed units according to a second embodiment;
(5) FIG. 4 shows a top view of a road paver having two attachment screed units according to a third embodiment;
(6) FIG. 5 shows a top view of an attachment screed unit according to a third embodiment;
(7) FIG. 6 shows a top view of an attachment screed unit according to an alternative embodiment; and
(8) FIG. 7 shows a top view of an attachment screed unit according to a further alternative embodiment.
(9) Like components are designated by like reference numerals. Components that are repeated are not designated separately in each drawing.
DETAILED DESCRIPTION OF THE INVENTION
(10) FIG. 1 shows a generic road paver 1 with a machine frame or chassis 2 and an operator platform 3. The road paver 1 further comprises an internal combustion engine (not shown), for example, a diesel engine, by means of which running gears 4 such as wheels or, as shown here, crawler tracks are driven via a suitable hydraulic system on the tractor. In working operation of the road paver 1, it lays and paves paving material in a layer in the working direction a, for example, for a road. To this end, the road paver 1 pushes with a push roller 32 a transport vehicle (not shown) in front of it, which is a dump truck, for example. The latter tips hot asphalt into the bunker or bucket 5 of the road paver 1. From the bunker 5, the asphalt is transported via scraper floors (not shown) through the tunnel situated in the interior of the road paver 1 to the rear and to the screed 6. The screed 6 on the illustrated road paver is in a lifted transport position. In working operation, the screed 6 is lowered toward the ground to be processed and floats on the material to be paved. The asphalt is distributed over the entire width of the screed 6 transversely to the working direction a, and is pre-compacted and smoothed by it. The pre-compacted asphalt layer is usually further compacted by road rollers (not shown) travelling behind the road paver until a complete, stable road surface has been produced.
(11) FIGS. 2 to 4 respectively show a top view of a road paver 1. The essential aspect in this case is that the road paver initially comprises a basic screed 7 which is arranged as a rigid screed, i.e., a screed without paving width adjustment, and which is fixed via towing arms 30 to the machine frame or the chassis 2 of the road paver 1. Attachment screed units 10 are attached directly or indirectly on the respective face ends, i.e., transversely to the working direction a, to said basic screed 7 in the different embodiments according to FIGS. 2 to 4. An attachment screed unit 10, which is arranged as an attachment module or attachment unit, respectively comprises a connecting screed 11 and an adjusting screed 12 which is mounted on the connecting screed 11 so as to be movable or adjustable horizontally and transversely to the working direction a, for example, by means of a three-point mounting system known in the art. The adjusting screeds 12 can be adjusted from the retracted position P.sub.1 to the extended position P.sub.2 on the connecting screed 11. As a result of the adjustment of the adjusting screeds 12, the paving width b.sub.3 of the attachment screed unit 10 is adjusted in a freely selectable manner between the two illustrated extreme positions P.sub.1, P.sub.2. The paving width b.sub.3 of the attachment screed unit 10 is smallest in the retracted position P.sub.1 and substantially corresponds to the paving width of the connecting screed 11. In the extended position P.sub.2 of the adjusting screed 12 which is shown in FIG. 3, the paving width b.sub.3 of the attachment screed unit 10 is greatest and substantially corresponds to the paving width of the connecting screed 11 plus the respective paving widths of the adjusting screed 12.
(12) The adjustment of the adjusting screeds 12 on the connecting screeds 11 transversely to the working direction a is respectively produced by an adjusting device which according to the present invention comprises an electro-hydraulic unit 15. The precise configuration of the adjusting device will be explained below in closer detail. As shown in the embodiment of FIG. 2 with respect to the power supply, the basic screed having a fixed paving width b.sub.1 is connected via the towing arms 30 to the machine frame of the tractor of the road paver. The basic screed is provided with a receptacle device on the face ends S of the basic screed 7 transversely to the working direction a, via which the connecting screeds 12 can be connected to the basic screed 7, preferably in a purely mechanical manner. The attachment device 16 is provided for this purpose on the face end of the connecting screed. The entire connection between the connecting screed 11 and the basic screed 7 is designated with reference numeral 34. The electro-hydraulic unit 15 of each attachment screed unit 10, which is arranged on the connecting screed 11, is respectively connected via an electric line 14 such as a cable to the on-board network 13 of the road paver 1 or its tractor. The electric line 14 is arranged in a space-saving manner in a cable drum on the attachment screed unit 10 and can be unrolled from said drum for the connection to the on-board network 13 in a rapid and uncomplicated manner. In FIG. 2, the attachment screed unit 10 which is on the right side as seen in the working direction a is in its retracted P1 position with minimal paving width, while the left attachment screed unit 10 is in its extended P2 position with maximum paving width. FIG. 2 thus illustrates that the total paving width B can be varied within a specific range by an adjustment of the adjusting screed 12 on the connecting screed 11. No hydraulic connection or other complex installation of the attachment screed units is necessary. Instead, it is only necessary to provide the mechanical coupling of the attachment screed units 10 with the rigid screed 7.
(13) In the embodiment according to FIG. 3, the basic screed 7 (a rigid screed in this case) is also fixed via the towing arms 30 to the machine frame or chassis 2 of the road paver 1. In order to extend the paving width b.sub.1 of the basic screed 7, extensions (intermediate screeds) in form of rigid attachment screeds 9 are mounted on its face ends situated transversely to the working direction a. They have an attachment screed width b.sub.2 by which the paving width b.sub.1 of the basic screed 7 is extended. In the embodiment of FIG. 3, a mechanical attachment screed 9 is respectively fixed to the ends of the basic screed 7 which are situated transversely to the working direction a, whereas in the embodiment of FIG. 4 further attachment screeds 9 are fixed to the outer ends of the attachment screeds 9 which are situated transversely to the working direction a. A respective attachment screed unit 10 is connected via the connecting screed 11 to the attachment screed units 10 at the ends of the attachment screeds 9 having fixed paving widths, which ends are situated on the outside transversely to the working direction a. The paving width b.sub.3 of the attachment screed unit 10 here also additionally increases the total screed width B, which is composed of the paving width b.sub.1 of the basic screed 7, the paving width b.sub.2 of the, in particular, mechanical, attachment screeds 9, and the paving width b.sub.3 of the attachment screed units 10. The total screed width B can be adjusted to the respective operating requirements by varying the paving width b.sub.3 of the attachment screed unit 10, i.e., by adjusting the adjusting screed 12 relative to the connecting screed 11.
(14) Since a respective attachment screed unit 10 is arranged on both sides or ends of the screed 6 which are situated transversely to the working direction a, an adjustment of the total screed width B can also be made asymmetrically. This is shown in FIG. 3, for example, in which the adjusting screed 12 of the attachment screed unit 10 which is situated on the right side in the working direction a is in the retracted position P.sub.1, whereas the adjusting screed 12 of the attachment screed unit 10 which is situated on the left side as seen in the working direction is situated in the extended position P.sub.2. In the embodiment of FIG. 4, however, the attachment screed unit 10 or its adjusting screed 12 which is situated on the right side as seen in the working direction a is in the extended position P.sub.2, whereas the attachment screed unit 10 or its adjusting screed 12 which is situated on the left side as seen in the working direction a is situated in a freely selected intermediate position between the maximum retracted position P.sub.1 and the maximum extended position P.sub.2. The electric lines 14 or cables for the electro-hydraulic units 15 of the respective attachment screed units 10 are laid through the attachment screeds 9 and the basic screed 7 up to the connection with the on-board network 13 of the road paver 1. Especially FIGS. 3 and 4 illustrate the considerable installation advantage which is achieved by the use of the attachment screed units 10 according to the present invention. Since the attachment screed units 10 merely require supply with electrical power for maintaining their functionality (which can also be provided by battery on the attachment screed unit 10 itself), the installation effort is very low and is limited to the mechanical connection via the connecting screed 11 on the one hand and, if necessary, the laying of an electric line to the on-board network of the tractor on the other hand. Consequently, no special precautions need to be taken for the installation on the basic screed 7 or the attachment screeds 9. The attachment screed units 10 according to the present invention merely need to be attached and still allow sufficient variability of the total paving width.
(15) FIGS. 5, 6 and 7 show individual embodiments of the attachment screed units 10 according to the sector W of FIG. 4 in detail and also apply similarly to the embodiments shown in FIGS. 2 and 3 with respect to the configuration and the function of the electro-hydraulic unit 15, in particular. It is a common feature of all embodiments that the adjusting screed 12 is situated in the extended position P.sub.2. An attachment device 16 is provided on the connecting screed 11 on the face end or on its narrow side in the horizontal plane, which attachment device is situated on the side of the connecting screed 11 beyond which the adjusting screed 12 cannot be moved, or which is opposite of the side beyond which the adjusting screed 12 can be adjusted relative to the connecting screed 11. The attachment device 16 is arranged in such a way that the connecting screed 11 and thus the attachment screed unit 10 can be attached via said attachment device either to a basic screed 7 or a mechanical attachment screed 9 for widening the entire screed width B. This can occur, for example, via screwed connections, retaining bolts, retaining hooks or similar elements. FIGS. 5, 6 and 7, respectively, disclose different details concerning the configuration of the electro-hydraulic unit 15 and the adjusting device 26 with the actuator 31.
(16) FIG. 6 shows an electro-hydraulic unit 15 with a fluid reservoir 18, an electric motor 19 for a hydraulic pump 20 and an electric connection 29, via which the electro-hydraulic unit 15 is connected to the electric line 14 and the on-board network 13 of the road paver 1. The electric motor 19 and the hydraulic pump 20 which is driven by the electric motor can also especially be arranged as a modular unit, so that the electric motor 19 is a part of the hydraulic pump 20. The electric motor 19 drives the hydraulic pump 20, which conducts the hydraulic fluid from the fluid reservoir 18 via the hydraulic lines 21 to the actuator 31, which in this case is a double-acting hydraulic cylinder 22, and pressurizes the same with hydraulic fluid. The hydraulic cylinder 22 connects the connecting screed 11 to the adjusting screed 12. The hydraulic cylinder 22 is either retracted or extended by pressurisation of the hydraulic cylinder 22 with hydraulic fluid by the hydraulic pump 20, and the adjusting screed 12 is thus adjusted between the retracted position P.sub.1 and the extended position P.sub.2.
(17) Furthermore, the attachment screed unit 10 comprises a highly schematically indicated operator control device 17 such as a control panel, via which an operator can control the adjustment of the adjusting screed 12. The adjustment of the adjusting screed 12 of the attachment screed unit 10 can be controlled directly by the operator on the operator control device 17 and is independent of other factors such as further attachment screed units 10 and the adjusting position of their adjusting screeds 12. It is thus possible for the operator to control the attachment screed unit 10 or the adjusting screed 12 of the attachment screed unit 10 according to the operating conditions directly present at the attachment screed unit 10 without having to consider other parts of the road paver 1.
(18) While the electric connection 29 is used in FIG. 5 for electrical contact of the electro-hydraulic unit 15, for example, for supplying the electric motor 19 and the control device 17, with the on-board network 13 of the road paver 1, such contact is not necessary in the embodiment of FIG. 6. A power source 23 in form of a battery is provided in this case, through which the electro-hydraulic unit 15 and especially the electric motor 19 and the control device 17 is supplied with power or current. The electric connection 29 can be integrated in this case in the electro-hydraulic unit for connection with the battery. No current-conducting connection is therefore necessary between the electro-hydraulic unit 15 and the road paver 1. The attachment screed unit 10 merely needs to be fixed via the attachment device 16 to the screed 6 of the road paver 1. Furthermore, it is merely necessary to connect the compacting devices in the attachment screed unit 10, for example, the tamping beam and the vibrating smoothing screed, to the respective mechanical drives of the said devices of the screed 6, whereas no hydraulic or electrical transmission of power to the attachment screed unit 10 is necessary. The electro-hydraulic unit is completely autonomous and does not require any power-transmitting connection to the tractor of the road paver for the adjustment of the screed width. A modification of the screed 6, i.e., the attachment or removal of the attachment screed units 10 can thus occur in an especially rapid and simple way. The operation of the actuator 31 or hydraulic cylinder 22 in the embodiment of FIG. 7 corresponds to the embodiment of FIG. 5.
(19) The embodiment of FIG. 7 shows an electro-hydraulic unit which is connected according to the embodiment in FIG. 5 via an electric connection 29 to the on-board network 13 of the road paver 1 or the tractor. The adjusting device 26 further comprises a hydraulic motor 24 which is driven by the hydraulic pump 20 and which supplies power in form of torque to a drive shaft 25. The drive shaft 25 transmits the torque to a rack-and-pinion drive 27 which utilises the torque in order to displace a toothed rack 28 transversely to the working direction a. The hydraulic motor 24 is arranged in reversible configuration, as a result of which the adjusting direction of the adjusting screed 12, i.e., the retraction or extension of the adjusting screed 12, can be controlled. It will be appreciated that other combinations of the power supply of the electro-hydraulic unit 15 with further embodiments of the actuator 31 as a linear drive can be considered. The advantages of the present invention are provided as long as the hydraulic adjustment of the adjusting screed 12 relative to the connecting screed 11 of the attachment screed unit 10 is separate from the hydraulic system of the road paver 1 (tractor), and the hydraulic fluid of the remaining hydraulic system of the road paver 1 (tractor) does not mix with the hydraulic fluid which is used for adjusting the adjusting screed 12 of the attachment screed unit 10.
(20) While the present invention has been illustrated by description of various embodiments and while those embodiments have been described in considerable detail, it is not the intention of Applicants to restrict or in any way limit the scope of the appended claims to such details. Additional advantages and modifications will readily appear to those skilled in the art. The present invention in its broader aspects is therefore not limited to the specific details and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of Applicants' invention.
