The invention relates to a method and a tamping unit for tamping a track according to the features cited in the introductory part of claims 1 and 5, respectively.
A tamping unit of this type is known from EP 1 653 003 A1, wherein, for tamping a track, tamping tines are moved towards one another in pairs. This squeezing motion for ballast compaction is carried out with the aid of a hydraulically actuatable squeezing cylinder. A vibration is superimposed hydraulically on the linear squeezing motion in order to thus achieve easier penetration into the ballast as well as improved compaction.
It is the object of the present invention to provide a method and a tamping unit of the kind mentioned at the beginning with which it is possible to improve the hydraulic generating of vibrations.
According to the invention, this object is achieved with a method or a tamping unit of the specified type by means of the features cited in the characterising part of claims 1 and 5, respectively.
With the combination of features according to the invention, an optimisation of the parameters required for the generation of vibrations is possible independently of the squeezing motion of the tamping tines. An improvement particularly with regard to the energy balance can be achieved if the vibration piston is effective as a spring-mass system. Using such an energy store, it is possible to significantly reduce the high hydraulic energy expenditure intrinsically required for generating vibrations. A further advantage resulting therefrom can be seen in reduced noise emission.
Additional advantages of the invention become apparent from the dependent claims and the drawing description.
The invention will be described in more detail below with reference to an embodiment represented in the drawing.
A tamping machine 1, visible in
The tamping unit 6 shown enlarged in
The squeezing drives 14, shown in detail in
Arranged in each squeezing drive 14 or squeezing cylinder 18, in addition to the squeezing piston 19 provided for the squeezing motion 8, is a vibration piston 24 designed for generating the vibrations. This vibration piston 24, in the two variants according to
As visible in
An oil chamber 31—formed by the cylinder bottom 25, the cylinder ring 27 and the piston rod 26 of the vibration piston 24—can be charged with high pressure via a hydraulic line 32 for generating a first oscillatory motion 33. An end position damping 34 is arranged on the vibration piston 24 and/or on the squeezing piston 19.
By corresponding positioning of the valve 22 and actuation of an oil chamber 44 delimited by the squeezing piston 19 and vibration piston 24, the squeezing piston 19 together with the squeezing piston rod 20 is set in motion which, in the course of the squeezing motion 8, brings together the two tamping tines 11 lying opposite one another in pairs (see
Via the hydraulic line 32, the volume flow for the vibration, or rather for the first oscillatory motion 33, is led to the oil chamber 31. In this, the vibration is generated by means of a rapidly switching valve 35. Said valve 35 can switch through the high pressure side in impulse-like fashion, causing the vibration piston 24 to be shifted towards the right and the mechanical spring 30 to be tensioned.
With the valve 35 in zero position, a connection to a storage container is established. In this position, a swimming position is possible. In further sequence, the spring 30 can now reset the vibration piston 24 (with a movement in the direction towards the cylinder bottom 25), and the hydraulic oil is discharged into the storage container. Thus, the role of the energy store 29 is taken over by the mechanical spring 30 (alternatively, the energy store 29 may also have the form of a bubble storage or the like). Thus, the vibration piston 24 and the springs 30 form an energy conservation system 36 in the shape of a spring-mass system. Ideally, the system 36 is operated near the resonant frequency of the spring-mass system. With the pressure relief valve 23, a squeezing pressure for the squeezing motion and thus a dynamic counter cushion is built up.
The advantage of the described solution versus the known fully hydraulic squeezing drives lies in the fact that the vibratory motion can be carried out independently of the motion of the squeezing cylinder 19. It is generally known that, in the known hydraulic drive, as a result of the superimposition of the squeezing—and vibratory motion, the volume stream becomes so high that the structural size of the valve becomes unnecessarily large, and the entire volume stream of the superimposed vibration is transformed into heat. This leads to high energy consumption.
It is further known or proven by measurements that, in the case of heavy encrustation of the ballast to be tamped, the oscillation amplitude with a known fully hydraulic system cannot be maintained (avoiding this disadvantage is only possible by increasing the structural size). The reason for this lies in the fact that no energy can be stored in the system in the short term.
In contrast to the indicated disadvantages in the known embodiments, an energy store is available in the power concept according to the invention by means of the spring-mass system (formed by the springs 30 and the vibration piston 24). This corresponds energetically to the function of a rotating oscillating mass, known from the prior art, having an eccentric drive for producing a tamping tine vibration. Furthermore in an advantageous way, the squeezing motion can be carried out independently of the oscillation amplitude of the vibration. This results in a simplified design of the valve for the squeezing cylinder 18.
In the variant of embodiment according to
The squeezing piston 19 and the squeezing piston rod 20 connected thereto have a bore 38, preferably extending coaxially to the axis 17, for the passage of a vibration impulse generating the first oscillatory motion 33 of the vibration piston 24 (see also
In the embodiments according to
Controlling or regulating the present invention is carried out by means of simple and robust sensors, and the required values for the controlling or regulating are determined by means of a model predictive system (observer). From known physical values which are easy to measure, or from the control values, the not-measured values of an observed reference system are determined.
Number | Date | Country | Kind |
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A 758/2015 | Nov 2015 | AT | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2016/001761 | 10/24/2016 | WO | 00 |