Machine and method for stabilizing ballast track

Abstract

A machine for stabilizing a track (7) having a ballast bed (8) includes a machine frame (5) supported on a rail running mechanism (6) and a stabilizing unit (13) capable of rolling on rails (10) of the track (7) by means of unit rollers (14), the stabilizing unit (13) including an exciter (15) for generating a dynamic impact force and a pressure device (19) for generating a load (F) acting on the track (7). The pressure device (19) is connected to a control device (20) for periodically varying the load (F) during the stabilization process. By periodically varying the load (F), proximal and distal regions of the load input are alternately affected, resulting in improved compaction results compared to a constant load. A method for stabilizing a ballast track is also provided.

Description

[Technical field]

[0001] The present invention relates to a machine for stabilizing a track having a ballast bed, the machine comprising a machine frame supported on a rail running mechanism and a stabilizing unit capable of rolling on the rails of the track by means of unit rollers, the stabilizing unit comprising an exciter for generating dynamic impact forces and a pressing device for generating loads acting on the track. The invention further relates to a method for carrying out the stabilization process with the machine. [Background technology]

[0002] In order to restore or maintain a predetermined track condition, the track with the ballast bed is periodically treated by a compactor, which travels along the track and lifts the track frame formed from sleepers and rails to an overcorrected target position by means of a lifting / adjusting unit. The new track position is fixed by compacting the track with the compactor unit. Here, a sufficient and particularly uniform load capacity of the track ballast is an important and fundamental prerequisite for the stability of the track condition during train operation.

[0003] Therefore, machines are usually used to stabilise the track after the compaction process. The track is loaded with a static load and locally vibrated. This vibration leads to the particles in the grain structure becoming mobile and able to shift, resulting in a tighter bearing. The ballast compaction achieved in this way increases the load-bearing capacity of the track and anticipates track subsidence due to compaction. An increase in lateral resistance also accompanies compaction. A corresponding method is disclosed in EP 1 817 463 A1.

[0004] A number of machines for stabilizing tracks are already known from the prior art. In so-called dynamic track stabilizers, a stabilizing unit, which is arranged between two rail running mechanisms, is pressed by a pressing device with a vertical load onto the track to be stabilized. Via the unit rollers, the lateral vibrations of the stabilizing unit are transmitted to the track under continuous forward running.

[0005] A corresponding machine is known, for example, from WO 2019 / 158288. Here, the stabilizing unit comprises an exciter with at least two unbalanced masses driven with a variably settable phase shift. By means of the variably settable phase shift, the impact force acting on the track can be varied in a targeted manner. The stabilizing unit is supported with a constant force against the machine frame by a hydraulic pressure drive. Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to improve the machine of the type mentioned at the beginning in order to improve the compaction results of the track ballast and to obtain additional information for the compaction control that is incorporated into the operation in order to determine the track condition. Furthermore, a corresponding method is to be presented. [Means for solving the problem]

[0007] These objectives are achieved according to the invention by the characterizing features of the independent claims 1 and 5. The dependent claims give advantageous embodiments of the invention.

[0008] Here, the pressing device is connected to a control device for periodically changing the load during the stabilization process. The frequency of the periodic change of the load is much lower than the vibration frequency of the exciter. The improvement of the compaction result achieved thereby is governed by soil mechanics. In the new track ballast, so-called ballast flow occurs under dynamic pressing. In this state, the ballast particles of the granular structure are rearranged and come to a denser bearing. By periodically increasing the load, the ballast flow in the load input area is locally blocked, which leads to a temporary longer-reaching compaction action. By periodically changing the load, the near and far regions of the load input are alternately affected. This results in an improved compaction result compared to a constant load. In other words, in the case of a constant load, the ballast flow leads to an increased dynamic decoupling between the dynamic excitation and the far-reaching regions of the load input.

[0009] The essential advantage of the invention is manifested during ballasting with changing ballast and substrate properties, since the cyclically varying load according to the invention leads to optimal compaction results even under changing conditions. In particular, in old and dirty track ballast where no ballast flow occurs, the invention shows a significant improvement in ballast compaction.

[0010] In an advantageous development of the invention, a number of sensors are arranged to detect the course of the forces acting on the track from the stabilizing unit, the measurement signals of which are fed to an evaluation device which is arranged to determine characteristic quantities derived from the course of the forces. The stabilizing unit and the ballast track form a dynamic interaction system, the movement of which makes it possible to obtain information about the characteristics of the track ballast state. This allows for a dynamic compaction control which is integrated into the work and a determination of the track state, and additional information is provided by deliberately changing the process parameters. The load substantially influences the friction between the sleeper bottom and the track ballast. In the evaluation of the compaction control associated with the process, therefore, a clearer distinction can be made between the ballast stiffness, the ballast state and the lateral displacement resistance.

[0011] A further improvement is obtained in that a closed control loop is provided with a controller, an actuator for the pressing device and a measuring device for detecting the process parameter for closed-loop control of the process parameter. The closed-loop control of at least one process parameter allows the stabilization process to be automatically adapted to changed conditions in the dynamic interaction system of the stabilization unit, the track frame and the track ballast.

[0012] An advantageous extension is obtained by arranging a further stabilisation unit with a further pressing device connected to a control device to generate a periodically changed load, which gives the possibility of coordinating the operation of the two stabilisation units with each other in order to obtain better compaction results.

[0013] In the method according to the invention for carrying out the stabilization process using the above machine, the stabilization unit is used to vibrate the track and a pressure device is used to apply a periodically varying load to the track during the stabilization process.

[0014] For dynamic compaction control and for determining the track state, it is advantageous if a sensor is used to detect the force curve acting on the track from the stabilization unit, and the measurement signal of the sensor is evaluated by means of an evaluation device in order to determine characteristic quantities derived from the force curve.

[0015] Another improvement of the method is obtained by setting a vibration frequency for the exciter that is adjusted to the interval of the periodically varying load. It is especially useful when several stabilization units are arranged one behind the other, taking into account the travel speed as well. When optimally adjusted, the vibration frequency of the exciter is at least a power of 10 higher than the frequency of the periodically varying load.

[0016] Advantageously, at least two stabilization units, each of which has its own pressure device and which are arranged one behind the other, are driven together, with each pressure device achieving a dedicated course of the load acting on the track.

[0017] Two advantageous operating modes are obtained by driving the two pressing devices synchronously or asynchronously, so that the two stabilizing units exert the same load on the track in synchronous mode and different loads in asynchronous mode. The synchronous mode is preferred for compaction control accompanying the process. The advantage of the asynchronous mode is that the machine frame is subjected to a constant load, since the two stabilizing units are not supported against the machine frame at the same time and with the same reaction force.

[0018] This method with multiple stabilization units is improved by setting an interval for the periodically changing load that is adjusted to the running speed of the machine. It is advantageous to adjust the interval of the load pulses to the running speed, so that the places treated with the smallest load by the leading stabilization unit are treated with the largest load by the trailing stabilization unit and vice versa.

[0019] This adjustment is possible for both synchronous and asynchronous modes. Within this bandwidth, the interval of pulsed loads is selected so that the stabilizer influence areas overlap (do not change too slowly), but the rate of load change allows for subsequent steady state oscillation conditions in dynamic orbit stabilization (do not change too quickly).

[0020] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0021] [Figure 1] FIG. 2 shows a stabilizer with two stabilization units. [Diagram 2] FIG. [Diagram 3] FIG. 13 shows a displacement-time diagram of the pressing path of the stabilization unit in synchronous mode with the longest pressing interval (fundamental vibration) together with the corresponding stabilization unit arrangement. [Figure 4] FIG. 13 shows the displacement-time diagram of the pressing path of the stabilization unit in synchronous mode with the second longest pressing interval (first harmonic vibration) together with the corresponding stabilization unit arrangement. [Diagram 5] FIG. 13 shows a displacement-time diagram of the pressing path of the stabilization unit in asynchronous mode with the longest pressing interval (fundamental vibration) together with the corresponding stabilization unit arrangement. [Figure 6] FIG. 1 shows the displacement-time diagram of the pressing path of the stabilization unit in the asynchronous mode with the third longest pressing interval (second harmonic vibration) together with the corresponding arrangement of the stabilization unit. [Figure 7] FIG. 13 shows the load variation over time of two stabilization units in synchronous mode at fundamental and harmonic frequencies with the accompanying displacement diagrams for a constant travel speed. [Figure 8]FIG. 2 shows the time evolution of different loads of two stabilization units in asynchronous mode plotted in succession at the fundamental and three harmonics with the accompanying displacement diagrams, when the travel speed is constant. [Figure 9] FIG. 13 is a diagram of the horizontal vibration amplitude of the stabilization unit versus load. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The machine according to the invention is configured as a free-standing stabilizer 1 (FIG. 1) or as a combined machine with a compactor 2 (FIG. 2) and a stabilizer 1 connected thereto. In the case of the free-standing stabilizer 1, this has a dedicated travel drive 3 and a dedicated cockpit 4. The machine 1 has a machine frame 5 which can run on a track 7 on a rail running mechanism 6.

[0023] The track 7 is a ballasted track with a track frame housed in a ballast track bed 8. The track frame consists of sleepers 9 and rails 10 fixed thereon. To correct the track position, the track frame is lifted to a new position by a lifting / adjusting unit 11 of the compactor 1. Fixing the track frame in the new position is performed by compacting the track ballast under the sleepers 9 with a compaction unit 12.

[0024] In order that after the treatment the new track position remains stable and the lateral slip resistance of the track 7 reaches the required level again after the maintenance, a stabilizer 1 is used, also called Dynamic Track Stabilizer (DGS). The aim is to bring the track ballast, which has been partially loosened by the compaction of the track 7, into a stable and denser state by means of the stabilizer 1 and then optimally compacting it.

[0025] For this purpose, the stabilizing machine 1 shown in FIG. 1 has two stabilizing units 13 arranged one behind the other and equipped with unit rollers 14 which press against the rail 10. In a simple form, only the stabilizing units 13 are arranged. In operation, each stabilizing unit 13 is vibrated in the track transverse direction by an exciter 15. The unit rollers 14 transmit vibrations to the track frame, whereby the track 7 is dynamically excited. The track ballast vibrates in the influence area 16 of the stabilizing units 13, which leads to compaction of the ballast. The vibration frequency of the exciter 15 is generally in the range of 33 Hz to 42 Hz.

[0026] For controlling the stabilizing unit 13 and the travelling drive 3, the stabilizer 1 has a machine control 17 which is possibly connected to a machine control 17 of the compactor 2. Furthermore, both the compactor 2 and the stabilizer 1 have a chord measuring system 18 for determining the track position.

[0027] Each stabilizing unit 13 is supported on the machine frame 5 by a pressure device 19. The pressure device 19 comprises, for example, two hydraulic cylinders which are pivotally mounted on both sides on the side beams of the machine frame 5. By means of the pressure device 19, the associated stabilizing unit 13 is pressed against the track 7 with a vertical load F (vertical load).

[0028] According to the invention, this cyclical change of the load F is carried out during the stabilization process. This targeted application of cyclical variations improves the compaction result compared to a stabilization process with a static vertical press. For this purpose, the press device 19 is connected to a control device 20, which in particular is configured with a control program in such a way that the cyclically changed manipulated variables are set for the press device 19. Advantageously, the control device 20 is connected to or integrated in the machine control 19, so that the travel speed v of the stabilization machine 1 and the cyclical change of the load F are coordinated with each other. The frequency of the cyclically changed load F is, for example, 1 Hz and is therefore significantly lower than the vibration frequency of the exciter 15, which is 33 Hz to 42 Hz.

[0029] It makes sense that each treated section of the track 7 will be subjected to different dynamic states occurring at the minimum load F, the maximum load F and in the transition areas between them. This will allow favourable soil mechanical behaviour to be exploited. Consider a time interval i for a load cycle of load F. This interval i of the cyclically changed load F must be adjusted to the distance a of the two stabilising units 13, to the way they operate (synchronous or asynchronous) and to the travelling speed v of the stabilising machine 1. In particular, it is ensured that at each point where the leading stabilising unit 13 is loaded with a maximum load F, the trailing stabilising unit 13 is loaded with a minimum load F and vice versa.

[0030] Here, the compactable influence area 16 plotted in Figures 3 to 8 is taken into consideration. On the one hand, gaps should not occur for optimal compaction (interval i is too long), and on the other hand, too fast load changes may prevent the desired stationary vibration state of the dynamic horizontal vibration (interval i is too short).

[0031] A steady vibration state is important for the successful application of the compaction control integrated into the operation. The load variation according to the invention expands the compaction control and the determination of the track state with additional possibilities. Details of the determination of the characteristic quantities for the compaction control and for the determination of the track state are evident from the Austrian patent application A331 / 2018, the content of which is incorporated herein by reference. In the stabilization unit 13, a sensor 21 for detecting the measurement signals and an evaluation device 22 for the determination of the characteristic quantities are arranged.

[0032] In synchronous mode, the same load F is cyclically applied to all stabilization units 13. As a result, the stabilization units 13, the track frame and the underlying track ballast form a joint dynamic interacting system, which facilitates the interpretation of the measurement results within the framework of the dynamic compaction control implemented in the operation.

[0033] However, alternating loading of the machine frame 5 may be undesirable. In the asynchronous mode, this alternating loading disappears, since the resultant force of the two stabilizing units 13 on the machine frame 5 remains constant. Only the load F is cyclically redistributed between the two stabilizing units 13, so that loading one stabilizing unit 13 necessarily entails unloading the other stabilizing unit 13. In this case, one stabilizing unit 13 reaches its maximum value max of the load F when the other stabilizing unit 13 reaches its minimum value min of the load F.

[0034] In Fig. 3 to Fig. 6 the pressing relationship is shown in a unified diagram. In the lower area the spatial arrangement of the stabilizing units 13 can be seen. Above this are arranged the respective time-displacement diagrams, in which the displacement s of the stabilizer 1 is shown against the time t. For a constant running speed v, there is a direct correlation between the displacement s (position) of each stabilizing unit 13 and the time t. Therefore, the displacement s is plotted on the horizontal axis and the time t on the vertical axis. Here, the following relation for the speed v is given by the displacement interval Δs and the time interval Δt, i.e. v=Δs / Δt holds true.

[0035] What can be seen in each diagram is the position of the stabilization unit 13 at each time point. Furthermore, the minimum pressure min (minimum load F) and the maximum pressure max (maximum load F) along the pressure path 23 of the front stabilization unit 13 and along the pressure path 24 of the rear stabilization unit 13 are plotted together with the time t and the displacement s (position). This makes it possible to create favorable conditions where the rear stabilization unit 13 has the minimum pressure min at the position where the front stabilization unit 13 has the maximum pressure max, and vice versa.

[0036] If the stabilization units 13 operate in synchronous mode (FIGS. 3 and 4), the maximum pressures max of the two stabilization units 13 occur at the same time point. The same applies to the minimum pressures min. In asynchronous mode, at the time point when one stabilization unit 13 has a maximum pressure max, the other stabilization unit 13 has a minimum pressure min (FIGS. 5 and 6).

[0037] In all operating modes, the advantageous condition formulated for different pressures min, max applies in the same place. The longest interval i of the periodically changed load F for which this condition is met is the interval i corresponding to the fundamental oscillation of the variable load F. This interval i is independent of the distance a of the stabilization unit 13, the running speed v and the operating mode (synchronous or asynchronous).

[0038] Corresponding to the diagram of FIG. 3, in the synchronous mode, the interval i of the fundamental vibration with the distance a between the stabilizing units 13 and the running speed v of the stabilizer 1 0 Regarding the following relation, i 0 =2×a / v is obtained. In the pressure paths 23, 24 of each stabilization unit 13, the harmonic vibrations are n whereas in synchronous mode, the following equation: i n =(2×a / v) / (2×n+1) n=1,2,3,… holds true. The first harmonic vibration is shown in figure 4. It is advantageous to select the harmonic vibration when the driving speed v is low and the distance a between the stabilization units 13 is large.

[0039] In asynchronous mode, the interval between fundamental vibrations i 1 Regarding (Figure 5), the following relationship exists: i 1 =a / v is obtained. In general, each interval i in asynchronous mode nFor the pressing paths 23, 24 of the two stabilizing units, the following equation is satisfied: i n =a / (n×v) n=1,2,3,… holds true.

[0040] In case of a large spacing a of the stabilization units 13 with gaps between the individual influence areas 16, a higher frequency harmonic oscillation of the load F to be changed is advantageously selected (FIG. 4 for synchronous mode).

[0041] Even when the speed v is very low, it may be effective to select a higher frequency harmonic vibration of the load F. In Fig. 6, the third harmonic (referred to as the second harmonic vibration) (n=3) is shown as an example for the asynchronous mode.

[0042] 7 and 8 show the load F over time. The geometrical relationship of the stabilization unit 13 is shown below for a constant running speed v and is given by the following relationship: t=s / v It has. Figure 7 shows the corresponding interval i 0 The fundamental oscillation for the synchronous mode, with a / v = 2 × a / v, is shown in solid line. The first harmonic oscillation is shown in dashed and dotted line, with a shorter interval i 1 = (2 × a / v) / 3. The second harmonic oscillation is shown by the dashed line and is spaced apart by the interval i 2 =(2×a / v) / 5.

[0043] For the asynchronous mode, FIG. 8 shows in solid lines the course of the load F for one stabilization unit 13 (pressing path 23) and in dashed lines the course of the load F for another stabilization unit 13 (pressing path 24). The fundamental vibration n1 and the three first harmonic vibrations n2, n3, n4 are shown next to each other in time order. 1 ,i 2 ,i 3 ,i 4 Here again, we have the following: in =a / (n×v) n=1,2,3,… holds true.

[0044] In FIG. 9, the additional use of the change in load F when using dynamic compaction control integrated into the operation is shown. The horizontal vibration amplitude y of the stabilization unit 13 DGS The idea based on this horizontal vibration amplitude y DGS varies depending on the load F. The horizontal vibration amplitude y of the stabilization unit 13 DGS replaces all measured and calculated quantities described in the Austrian patent application A331 / 2018 as well as additional measurements such as ambient vibrations (magnitude and shape of wave propagation).

[0045] When the load F increases, the amplitude y DGS Then, when the load is reduced, the amplitude y DGS increases again in the second section 26. Due to hysteresis, these two sections 25, 26 do not extend on the same line. However, the two sections 25, 26 have a discernible inflection point 28 in the narrow load region 27, which indicates a system modification in the dynamic interaction system of stabilization units-track frame-track ballast. The position of this system modification is an additional indicator of the ballast condition and correlates with the lateral slip resistance of the track 7. This indicator can also be used for the automatic control of process parameters.

Claims

1. 1. A machine for stabilizing a track (7) having a ballast bed (8), comprising a machine frame (5) supported on a rail running mechanism (6) and a stabilizing unit (13) capable of rolling on rails (10) of the track (7) by means of unit rollers (14), the stabilizing unit (13) comprising an exciter (15) for generating a dynamic impact force and a pressing device (19) for generating a load (F) acting on the track (7), the pressing device (19) being connected to a control device (20) for periodically varying the load (F) during the stabilization process, the pressing device (19) being set to coincide with an interval (i) of the periodically varying load (F) and a vibration frequency of the exciter (15).

2. 2. The machine according to claim 1, characterized in that a number of sensors (21) are arranged for detecting the course of a force (F) acting on the track (7) from the stabilization unit (13), the measurement signals of the sensors (21) being supplied to an evaluation device (22), the evaluation device (22) being configured to determine characteristic quantities derived from the course of the force.

3. 3. The machine according to claim 1 or 2, characterized in that for closed-loop control of a process parameter, a closed control loop is provided with a controller, an actuator for the pressure device (19) and a measuring device for detecting the process parameter.

4. 4. The machine according to claim 1, further comprising a further stabilising unit (13) provided with a further pressing device (19) connected to the control device (20) for generating a periodically varying load (F).

5. 5. A method for carrying out a stabilization process with a machine according to any one of claims 1 to 4, characterized in that the stabilization unit (13) is used to oscillate the track (7), characterized in that during the stabilization process, a periodically varying load (F) is applied to the track (7) by means of the pressing device (19) at intervals (i) and that the exciter (15) is set to a vibration frequency which is adjusted to the intervals (i) of the periodically varying load (F).

6. 6. The method according to claim 5, characterized in that a force profile acting on the track (7) from the stabilization unit (13) is detected by means of a sensor (21) and a measurement signal of the sensor (21) is evaluated by means of an evaluation device (22) in order to determine a characteristic quantity derived from the force profile.

7. 7. The method according to claim 5 or 6, characterized in that two stabilizing units (13) arranged one behind the other and each equipped with its own pressing device (19) are driven together.

8. 8. The method according to claim 7, characterized in that the two pressing devices (19) are driven synchronously or asynchronously, whereby the two stabilizing units (13) apply the same load (F) to the track in synchronous mode and different loads (F) in asynchronous mode.

9. 9. A method according to claim 7 or 8, characterized in that for the load (F) which is changed periodically, intervals (i) are set which are adjusted to the running speed (v) of the machine.

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