Patent Application
20210010206
The invention relates to a tamping assembly for a track tamping machine having tamping tool pairs, which are arranged on a girder guided vertically-adjustable in a tamping assembly frame and are formed as rocker arms, and the lower tamping pick ends of which, which are intended to plunge into a ballast bed, are drivable using an oscillating drive and can be hydraulically closed toward one another, wherein a hydraulic cylinder and possibly a distance sensor for determining the hydraulic cylinder position are associated with each of the tamping tools of a tamping tool pair, and the hydraulic cylinders form both the linear closing drive and also the oscillating drive of the tamping tools, and wherein electrohydraulic valves are provided for actuating the hydraulic cylinders, which comprise a mechanic hydraulic cylinder actuation valve part and an associated valve electronic unit.
Tamping assemblies penetrate the ballast of a rail bed using tamping tools in the region between two sleepers (divider), in the region of the support of the sleeper in the ballast under the rail, and compact the ballast by way of a dynamic vibration of the tamping picks between the opposing tamping picks, which are closable toward one another. Tamping assemblies can tamp one, two, or more sleepers in one work cycle (DE 24 24 829 A, EP 1 653 003 A2). According to the teaching of EP 1 653 003 A2, the closing drives acting as a linear drive are embodied in such a way that they generate not only a linear closing movement, but rather simultaneously also the vibration required for the tamping picks in a manner known from AT 339 358, EP 0 331 956, or U.S. Pat. No. 4,068,595. The closing speed, the oscillation amplitude, their form, and the frequency can thus be predetermined.
The movements of a tamping assembly comprise the vertical plunging of the tamping picks into the ballast, the closing movement during which the tamping pick ends are closed toward one another, and the overlaid dynamic oscillation which effectuates the actual compaction of the ballast grains. Using hydraulic cylinders for the closing movement, which moreover form the tamping drive, is known (AT513973A).
Optimum tamping frequencies for compaction are known to be between 25-40 Hz, wherein a penetration of the tamping picks into the ballast is possible more easily at higher frequencies, since only a lesser plunging shock occurs and thus the stress of the bearings of the tamping pick assembly can be reduced.
The known solutions of fully hydraulic linear tamping drives (AT513973A), which have a combination of hydraulic cylinder and a control valve constructed directly on the hydraulic cylinder for simultaneously generating the vibration and the closing movement are subjected to high accelerations generated by the vibration. In particular the control valves constructed directly on the cylinder and/or their actuation electronic unit integrated into the valve are thus highly stressed. The lifetime of the valves is thus shortened and the service life decreases. Another disadvantage is that the A, B lines of the hydraulic valve have to be integrated directly into the cylinder as boreholes.
The size and the costs of the special cylinder thus increase. The increasing size of the cylinder is a disadvantage with respect to the constricted space conditions in tamping assemblies. In addition, high pressure variations occur at the pressure lines and tank lines of the control valve, which additionally stress the control valve. These pressure peaks also stress the fittings of the hydraulic lines and the hydraulic lines themselves, on the other hand. This results in a reduction of the lifetime and also in the challenge of keeping the hydraulic screw connections leak-tight in the long term.
The invention is thus based on the object of refining tamping assemblies of the type described at the outset using simple means in such a way that the durability of the fully hydraulic tamping drive is significantly increased.
The invention achieves the stated object in that the valve electronic unit is mounted in a vibration-damped manner with respect to the hydraulic cylinder and/or the mechanic hydraulic cylinder actuation valve part by means of vibration dampers.
The valve electronic unit of the hydraulic control valve is constructed separately from the (electro-)mechanical part of the hydraulic control valve. The valve electronic unit can thus be mounted in a vibration-damped manner with respect to the hydraulic cylinder and/or the mechanical hydraulic cylinder actuation valve part. The vibration-damping mounting can be formed by corresponding rubber-elastic elements, by spring damper elements, or the like. The durability of the fully hydraulic tamping drive is significantly increased by this measure.
The valve electronic unit and the mechanic hydraulic cylinder actuation valve part can also be mounted in a vibration-damped manner with respect to the hydraulic cylinder by means of vibration dampers each as such or jointly.
One possible embodiment of the invention is to arrange the valve electronic unit and possibly the mechanical hydraulic cylinder actuation valve part spaced apart from the hydraulic cylinder, correspondingly in a vibration-damped manner. The mechanical hydraulic cylinder actuation valve part can also be arranged directly on the hydraulic cylinder in a vibration-damped manner by means of vibration dampers. Moreover, there is the option of arranging the valve electronic unit in a vibration-damped manner by means of vibration dampers directly on the mechanical hydraulic cylinder actuation valve part.
Moreover, it is advantageous if a hydraulic accumulator is arranged in a hydraulic pressure supply line to the mechanical hydraulic cylinder actuation valve part and/or if a hydraulic accumulator is installed in a hydraulic tank return line from the mechanical hydraulic cylinder actuation valve part. Wear-promoting pressure peaks can thus be reduced.
A valve constructed separately from the hydraulic cylinder moreover has the advantage according to the invention that a simple cost-effective cylinder of smaller construction can be used. The construction of hydraulic accumulators in the immediate vicinity of the hydraulic control valve reduces the pressure peaks in the hydraulic lines and thus also the stresses of the hydraulic control valve, the seals, the fittings, and the hydraulic lines themselves. The susceptibility to fault is strongly reduced by the vibration-damped mounting of the valve electronic unit, which is susceptible to malfunction.
The subject matter of the invention is illustrated by way of example in the drawings. In the figures
A distance sensor 17 is integrated into the hydraulic cylinder 11. An embodiment as an inductive distance sensor is shown here, wherein a position magnet 24 is provided, via which the deflection of the piston 21 is measured. If the cylinder chamber 23 is subjected to pressure P via the connection B, the piston moves to the left. If the pressure application of the piston via the valve 25 changes to the connection A, the piston 21 then moves to the other side. The valve electronic unit (13) is mounted in a vibration-damped manner on the mechanical hydraulic cylinder actuation valve part 12 via vibration dampers (D).
During the tamping, the tamping picks plunge into the ballast 4 of a track 1 and compact the ballast 4 under the sleepers 2. The sleepers 2 are fastened on the rails 6. The tamping arms 3 are articulated on the tamping box 7. The tamping box 7 is moved up and down on vertical guides 8 via a drive 9. In the figure, according to the invention, the mechanical hydraulic cylinder actuation valve part 12 is constructed separately from the shock-sensitive valve electronic unit 13. A control and regulation electronic unit 14 is connected to the distance sensors 17 via electrical connecting lines 16. In addition, the valve electronic parts 13 are actuated via the control lines 15. The control valve parts 12 which are directly in the special cylinder 11 are supplied using the pressure line P and the tank line T.
| Number | Date | Country | Kind |
|---|---|---|---|
| GM50009/2018 | Jan 2018 | AT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/AT2019/050001 | 1/8/2019 | WO | 00 |
