METHOD FOR COMPACTING ASPHALT MATERIAL

Abstract

A method for compacting asphalt material (A) by means of at least one soil compactor (10) having at least one compactor roller with a motion generation arrangement assigned to the same, comprising the measures: a) detection of an asphalt temperature of the asphalt material (A) to be compacted, b) static compaction of the asphalt material (A) with a deactivated motion generation arrangement of the at least one compactor roller, if the asphalt temperature lies above an upper threshold temperature (O), c) static compaction of the asphalt material (A) with a deactivated motion generation arrangement of the at least one compactor roller, if the asphalt temperature lies below a lower threshold temperature (U),
wherein the upper threshold temperature (O) and/or the lower threshold temperature (U) is/are set depending on at least one surroundings parameter (T) influencing the cooling behavior of the asphalt material to be compacted.

Claims

1. Method for compacting asphalt material by at least one soil compactor having at least one compactor roller with a motion generation arrangement assigned to the same, comprising: a) detecting of an asphalt temperature of the asphalt material to be compacted, b) statically compacting of the asphalt material with a deactivated motion generation arrangement of the at least one compactor roller, if the asphalt temperature lies above an upper threshold temperature, c) statically compacting the asphalt material with a deactivated motion generation arrangement of the at least one compactor roller, if the asphalt temperature lies below a lower threshold temperature, wherein the upper threshold temperature and/or the lower threshold temperature is/are set depending on at least one surroundings parameter influencing the cooling behavior of the asphalt material to be compacted.

2. Method according to claim 1, wherein the upper threshold temperature and/or the lower threshold temperature is/are set depending on at least two surroundings parameters influencing the cooling behavior of the asphalt material to be compacted.

3. Method according to claim 1, wherein the upper threshold temperature and/or the lower threshold temperature is/are set depending on a surroundings temperature as the surroundings parameter influencing the cooling behavior of the asphalt material to be compacted.

4. Method according to claim 3, wherein the upper threshold temperature is increased at a decreasing surroundings temperature, and/or that the lower threshold temperature is decreased at decreasing surroundings temperature.

5. Method according to claim 1, wherein the upper threshold temperature and/or the lower threshold temperature is/are set depending on a wind speed as the surroundings parameter influencing the cooling behavior of the asphalt material to be compacted.

6. Method according to claim 5, wherein the upper threshold temperature is increased at an increasing wind speed, and/or that the lower threshold temperature is decreased at an increasing wind speed.

7. Method according to claim 1, wherein the asphalt material to be compacted is compacted using an activated motion generation arrangement of at least one compactor roller at an asphalt temperature lying in an intermediate temperature range, delimited by the upper threshold temperature and the lower threshold temperature.

8. Method according to claim 7, wherein, in an upper temperature range of the intermediate temperature range adjacent to the upper threshold temperature, the motion generation arrangement of at least one compactor roller is operated in a motion excitation operating state with a larger energy input, and that, in a lower temperature range of the intermediate temperature range adjacent to the lower threshold temperature, the motion generation arrangement of at least one compactor roller is operated in a motion excitation operating state (k) with a lower energy input.

9. Method according to claim 8, wherein the motion generation arrangement is drivable in a plurality of discrete motion excitation operating states with different energy inputs, and that the motion generation arrangement is operated in a motion excitation operating state with a larger energy input at an asphalt temperature lying above at least one intermediate threshold temperature lying in the intermediate temperature range, and is operated in a motion excitation operating state with a lower energy input at an asphalt temperature lying below the at least one intermediate threshold temperature.

10. Method according to claim 9, wherein the motion generation arrangement is drivable in two motion excitation operating states with different energy inputs, and that the motion generation arrangement is operated in a motion excitation operating state with a higher energy input at an asphalt temperature lying above the intermediate threshold temperature, and is operated in a motion excitation operating state with a lower energy input at an asphalt temperature lying below the intermediate threshold temperature.

11. Method according to claim 8, wherein at least one intermediate threshold temperature is set depending on at least one surroundings parameter influencing the cooling behavior of the asphalt material to be compacted.

12. Method according to claim 11, wherein the intermediate threshold temperature is set depending on the surroundings temperature as the surroundings parameter influencing the cooling behavior of the asphalt material to be compacted.

13. Method according to claim 12, wherein the intermediate threshold temperature is decreased at a decreasing surroundings temperature.

14. Method according to claim 11, wherein the intermediate threshold temperature is set depending on the wind speed as the surroundings parameter influencing the cooling behavior of the asphalt material to be compacted.

15. Method according to claim 14, wherein the intermediate threshold temperature is decreased at an increasing wind speed.

16. Method according to claim 7, wherein the motion generation arrangement is operable with an energy input continuously variable between a minimum energy input and a maximum energy input.

17. Method according to claim 16, wherein, for an asphalt temperature lying at or in the range of the upper threshold temperature, the motion generation arrangement is operated with a maximum energy input, and/or that for an asphalt temperature lying at or in the range of the lower threshold temperature, the motion generation arrangement is operated with a minimum energy input.

18. Method according to claim 1, wherein the motion generation arrangement assigned to at least one compactor roller is a vibration arrangement, and/or that the motion generation arrangement assigned to at least one compactor roller is an oscillation arrangement.

19. Method according to claim 18, wherein at least one soil compactor has two compactor rollers, wherein a vibration arrangement is assigned to each compactor roller, and/or that at least one soil compactor has two compactor rollers, wherein a vibration arrangement is assigned to one of the compactor rollers and an oscillation arrangement is assigned to the other compactor roller.

Description

[0030] The present invention is subsequently described in detail with reference to the appended figures. As shown in:

[0031] FIG. 1 a soil compactor with two compactor rollers usable for carrying out a method for compacting asphalt material;

[0032] FIG. 2 a depiction to illustrate the transition between different operating states of a motion generation arrangement provided in assignment to a compactor roller depending on the surroundings temperature;

[0033] FIG. 3 in one part a) the transition between different operating states for a soil compactor with two vibratory rollers, and in one part b) the transition between different operating states in a soil compactor with one vibratory roller and one oscillation roller;

[0034] FIG. 4 a depiction corresponding to FIG. 2 to illustrate the transition between different operating states, depending on wind speed.

[0035] In FIG. 1, a soil compactor, usable to compact asphalt material A, is generally designated with 10. Soil compactor 10 in the depicted embodiment is designed with a central compactor frame 12, on which an operator's station 13 is provided for an operator operating soil compactor 10. A compactor roller 14, 16 is respectively mounted to be rotatable about a respective roller axis of rotation on a front end area and on a rear end area of central compactor frame 12, wherein each of the two compactor rollers 14, 16 is pivotable with respect to central compactor frame 12 about a, for example, substantially vertical steering axle for steering soil compactor 10.

[0036] Soil compactor 10 advantageously has a motion generation arrangement assigned to each of two compactor rollers 14, 16. This type of motion generation arrangement may be designed as a vibration arrangement in order to generate a force or acceleration acting on respective compactor roller 14 or 16 substantially orthogonal to its respective roller axis of rotation. This type of vibration arrangement generally comprises an unbalanced mass arrangement, arranged in the interior of respective compactor roller 14 or 16 and rotatable about an unbalanced rotational axis, with a center of mass eccentric to the unbalanced rotational axis, which may advantageously correspond to the respective roller axis of rotation. Due to this type of vibration arrangement and the force or acceleration acting orthogonal to the roller axis of rotation, a periodic impacting load is exerted on asphalt material A to be compacted.

[0037] In one alternative embodiment, this type of motion generation arrangement may be designed as an oscillation arrangement, by means of which a periodically accelerating, back and forth oscillation torque is generated [in] respective roller 14 or 16 about its roller axis of rotation. Due to this type of periodic oscillation movement superimposed on the rotation of a respective compactor roller 14, 16 during movement of soil compactor 10 across asphalt material A to be compacted, a walking or kneading effect is generated, leading to an increase in the degree of compaction of asphalt material A. This type of oscillation arrangement may comprise, for example, two unbalanced mass arrangements with a center of mass, eccentric to the respective unbalanced rotational axis and rotatable about respective unbalanced rotational axes, wherein the two unbalanced rotational axes are eccentric to the roller axis of rotation, for example, lying diametrically opposite one another with respect to the roller axis of rotation and parallel to the same.

[0038] Soil compactor 10 may comprise, for example, a vibration arrangement assigned to each of two compactor rollers 14, 16. In one alternative embodiment, soil compactor 10 may comprise, for example a vibration arrangement assigned to one of two compactor rollers 14, 16 and may comprise an oscillation arrangement assigned to the other of two compactor rollers 14, 16.

[0039] In particular, if this type of motion generation arrangement is designed as a vibration arrangement, then this may be operated in different motion excitation operating states. It is assumed for the subsequent description that this type of vibration arrangement may be operated in two motion excitation operating states with different energy inputs, which is advantageously achieved in that, at a rotational speed of a respective unbalanced mass arrangement assumed to be substantially constant, the mass, acting on or combined with the center of mass, is switchable in the same. This switching may be induced, for example, by changing the rotational direction of the unbalanced mass arrangement and a relative circumferential movement of two mass parts of the unbalanced mass arrangement caused by this. Depending on the motion excitation operating state, the vibratory roller in this type of vibration arrangement may be operated with a larger excitation amplitude g or with a smaller excitation amplitude k. If the motion generation arrangement assigned to a compactor roller 14 or 16 is deactivated, then compactor roller 14 or 16 functions in a static operating state s, and thus compacts asphalt material A, traveled over by the same, merely with the static load exerted on this asphalt material A.

[0040] During spreading of asphalt material A, for example, during road construction by means of one or more asphalt pavers 18, the temperature of asphalt material A decreases in the area lying behind asphalt paver 18 at increasing distance from asphalt paver 18. This means that areas of different distances from asphalt paver 18 have different temperatures. In FIG. 2, the decrease of the asphalt temperature at increasing distance from asphalt paver 18 is illustrated by a decreasing thickness of depicted asphalt material A.

[0041] In order to be able to achieve a desired or optimal compaction result during compaction of asphalt material A, spread by asphalt paver 18, while taking into account, for example, a predetermined compaction plan for a compaction process, one or more soil compactors 10 work in different operating states in different temperature ranges. Thus, for example, only static compacting is used in an area directly following asphalt paver 18, in which asphalt material A has a comparatively high temperature. This means that, in this area, one or more motion generation arrangements, provided in this type of soil compactor 10, are deactivated. If the asphalt temperature drops below an upper threshold temperature O, in at least one of compactor rollers 14, 16, one motion generation arrangement assigned to the same may be activated, in order to compact already somewhat cooled down asphalt material A not only using the static load, but also by introducing energy generated by a motion generation arrangement assigned to one of respective compactor rollers 14, 16.

[0042] If the asphalt temperature drops below a lower threshold temperature U, this transitions back into a static operating state s, since further compaction of asphalt material A is no longer achievable at an asphalt temperature lying below lower threshold temperature U, even when operating a motion generation arrangement and the energy input induced thereby, but instead there is a risk that the structural integrity of the already compacted and cooled down asphalt material A is damaged.

[0043] In an intermediate temperature range Z, lying between upper threshold temperature O and lower threshold temperature U, the motion generation arrangement assigned to at least one of compactor rollers 14 or 16 is operated in soil compactor 10 in order to achieve the desired compaction of asphalt material A in this intermediate temperature range Z through the additional introduction of energy. It may thereby be advantageous to work with a larger energy input at a higher asphalt temperature, whereas then, when the asphalt temperature has already decreased in intermediate temperature range Z, it may be worked, for example, with a lower energy input. In the previously described case, in which the motion generation arrangement is a vibration arrangement, which may be operated in two motion excitation operating states g, k, with a larger energy input, thus a larger amplitude, and a smaller energy input, thus a smaller amplitude, then the transition between these two motion excitation operating states may be carried out at an intermediate threshold temperature M. If the asphalt temperature drops below this intermediate threshold temperature M, then the motion excitation operating state is switched from motion excitation operating state g with the larger amplitude to motion operating state k with the smaller amplitude. If the asphalt temperature also drops below lower threshold temperature U, the motion generation arrangement is transitioned into static compaction operation, in this case, a vibration arrangement is thus deactivated.

[0044] The temperature of asphalt material A spread by asphalt paver 18 depends strongly on surroundings parameters influencing the cooling behavior of asphalt material A. One of the surroundings parameters substantially influencing this cooling behavior is surroundings temperature T. At a low surroundings temperature T, asphalt material A cools down faster than at a higher surroundings temperature T. Wind speed W also substantially influences the cooling behavior of asphalt material A. A higher wind speed W leads to a significantly stronger energy discharge, and thus to a faster cooling down of asphalt material A, than a lower wind speed W.

[0045] By taking the surroundings parameter influencing this type of cooling behavior of asphalt material A into account, the different threshold temperatures O. M, U may be adjusted in order to guarantee that sufficient time is available, above all to carry out a compacting process with additional introduction of energy into asphalt material A, thus with an activated motion generation arrangement, for example, to be able to execute a compacting plan with, for example, a plurality of traverses. This adjustment or selection of different threshold temperatures O, M, U, depending on surroundings parameters, is subsequently described in detail with reference to FIGS. 2 to 4.

[0046] FIG. 2 shows the consideration of surroundings temperature T as the parameter influencing the cooling behavior of asphalt material A to be compacted. Three different surroundings temperatures T.sub.H, T.sub.T and T.sub.M are depicted in FIG. 2. T.sub.H is a state of a comparatively high surroundings temperature T, for example, in the range from 30 to 40° C. State T.sub.M may correspond to an intermediate surroundings temperature T, for example, in the range from 10 to 20° C., while state T.sub.T may correspond to a comparatively low surroundings temperature in the range of less than 10° C.

[0047] It is quite clear in FIG. 2 that upper threshold temperature O, dropping below which triggers a transition from a static compaction operation to a compaction operation with additional energy input, thus a motion excitation operating state, is increased at decreasing surroundings temperature T. This means that, at a low surroundings temperature T, working with a larger amplitude, for example, in motion excitation operating state g, is begun at a higher asphalt temperature, that at a higher surroundings temperature T. This leads to the fact that the temperature window, which is available for the compaction operation with additional energy input, is extended upward. Likewise, at a decreasing surroundings temperature T, lower threshold temperature U is displaced into lower temperatures. This means that, at a decreasing surroundings temperature T, the transition to a static compaction operation is delayed, which likewise leads to the fact that the temperature window available for the operating state with additional energy input is extended. Due to the extension of the temperature window lying between threshold temperatures O and U at decreasing surroundings temperature T, the faster cooling down of asphalt material A at decreasing surroundings temperature T is compensated, so that sufficient time is available, also at low surroundings temperatures, in order to suitably compact asphalt material A, for example, according to a predetermined compaction plan. The risk, that due to a time available for this work process being too short, which places an operator under time pressure, and thus stress-caused operating errors may occur, may thus be minimized or excluded.

[0048] It is further clear in FIG. 2 that intermediate threshold temperature M is also decreased at decreasing surroundings temperature T. This also means that, to carry out the compaction operation with a larger energy input or larger amplitude, a larger temperature window is available, thus compensating for a faster cooling down, and thus motion excitation operating state g, with a larger energy input, thus a larger amplitude, which is particularly important for a suitable compaction of asphalt material A, may be carried out in the predetermined measure.

[0049] FIG. 3a) illustrates predetermined values for upper threshold temperature O, intermediate threshold temperature M, and lower threshold temperature U for a soil compactor 10 with two compactor rollers 14, 16 designed as vibratory rollers for different surroundings temperatures or temperature ranges. In each case, column v respectively shows the operating state to be set for front compactor roller 14 and column h respectively shows the operating state to be set for rear compactor roller 16. Three layers, L1, L2, and L3, correspond to a three-layer structure, with support layer L1 to be arranged below, binder layer L2 to be arranged on support layer L1, and cover layer L3 to be arranged over binder layer L2 and providing the upper side.

[0050] It is clear in FIG. 3a) that, at an asphalt temperature lying above upper threshold temperature O, both compactor rollers 14, 16 are operated statically, thus, the motion generation arrangements assigned to the same are deactivated, which is also the case when the asphalt temperature lies below lower threshold temperature U. At an asphalt temperature lying in intermediate temperature range Z, thus between upper threshold temperature O and lower threshold temperature U, two compactor rollers 14, 16 or the motion generation arrangements respectively assigned to the same are operated in motion excitation operating state g with a large energy input, in motion excitation operating state k with a small energy input, or statically, depending on whether the asphalt temperature is above or below intermediate threshold temperature M, and depending on which of three layers L1, L2, L3 is to be compacted. It is also clear in FIG. 3a) that different threshold temperatures O, M, and U are selected for different surroundings temperatures T or ranges of surroundings temperature T, so that upper threshold temperature O increases at decreasing surroundings temperature T, while intermediate threshold temperature M and lower threshold temperature U decrease at decreasing surroundings temperature T.

[0051] FIG. 3b) correspondingly illustrates the selection of different threshold temperatures O, M, and U for a soil compactor 10, in which, for example, a vibration arrangement is assigned to front compactor roller 14, which is thus a vibratory roller, while an oscillation arrangement is assigned to rear compactor roller 16, which is thus an oscillation roller. The same temperature-dependent tendency of different threshold temperatures O, M, and U is clear in FIG. 3b). Further, it is also clear that the vibration arrangement assigned to front compactor roller 14 may be operated in different motion excitation operating states g and k, depending on different layers L1, L2, or L3 to be compacted. The oscillation arrangement assigned to rear compactor roller 16 is operated in this example only in a motion excitation operating state o, and may thus be either activated or deactivated. A switching of the oscillation arrangement between motion excitation operating states with different energy inputs is not provided in this exemplary embodiment.

[0052] FIG. 4 illustrates the consideration of wind or of wind speed W when setting different threshold temperatures O, M, U. Four different wind states or wind speeds W.sub.0, W.sub.1, W.sub.2 and W.sub.3 are depicted in FIG. 4. State W.sub.0 is thereby depicted as a wind-free state, while states W.sub.1, W.sub.2 and W.sub.3 depict states with an increasing wind speed W. A high wind speed W means a faster cooling down of asphalt material A and thus influences its cooling behavior in a way similar to a low surroundings temperature T. Correspondingly, at an increasing wind speed W and thus an increasingly faster cooling down of asphalt material A, upper threshold temperature O is increased in order to transition earlier, that is, at higher temperatures, from static compaction operation into a compaction operation with additional energy input. In the example illustrated here of a soil compactor 10 with a compactor roller 14 or 16 with a vibration arrangement assigned to the same, for example, motion excitation operating state g with a larger energy input, thus a larger amplitude, may be entered into upon exceeding the upper threshold temperature.

[0053] intermediate threshold temperature M, at which a switching is carried out from motion excitation operating state g with a large energy input to a motion excitation operating state k with a small energy input, is displaced to lower temperatures at increasing wind speed, so that the temperature window, available for carrying out the compaction operation using motion excitation operating state g with a large energy input, is a correspondingly larger temperature window compensating for the faster cooling down. Likewise, lower threshold temperature U, dropping below which triggers the transition into static compaction operation s, is displaced to lower temperatures at an increasing wind speed W.

[0054] The consideration of different parameters, to be take into consideration in the cooling behavior or asphalt material A, previously described with respect to FIGS. 2 to 4, may be combined in particularly advantageous ways. Thus, both surroundings temperature T and also wind speed W may be taken into consideration in setting threshold values O, M, and U. For example, a base value for respective threshold temperature O, M, or U may be respectively selected when taking surroundings temperature T into consideration on the basis of the tables illustrated in FIG. 3a) or 3b), which base value may be corrected by taking wind speed W into consideration, for example, it may be displaced or proportionally changed by a respectively predetermined temperature amount, depending on the wind speed. It is also possible to specify a base value, taking wind speed W into consideration, and adjusting this base value depending on the surroundings temperature, likewise the specification of correction values, which depend on wind speed W or surroundings temperature T and may then be used, for example, in addition to the specification of a respective threshold temperature.

[0055] The different values to be considered in the previously described method, thus the asphalt temperature, surroundings temperature T, and wind speed W, may be detected by suitable sensors, known in the prior art, and passed to a control unit in the form of respective detection signals. For example, the asphalt temperature may be detected by optical sensors, e.g., infrared sensors, while the surroundings temperature may be detected by a conventional temperature sensor, and the wind speed may be detected by a windmill with a rotational speed sensor assigned to the same. In the control unit, which may be designed with a microprocessor with a work program stored or executed therein, these variables may be processed in the previously described way, and automatically used to predetermine the suitable operating state for compactor rollers 14, 16 or the motion generation arrangements assigned to the same, depending on the temperature that asphalt material A currently has, which is to be respectively traveled over by soil compactor 10. The opportunity may thereby be provided for an operator to intervene in this automatic operation, in that the threshold temperatures, specified for the respectively prevailing surroundings conditions, may be additionally displaced, in a limited temperature range, by the operator in the direction of higher or lower temperatures.

[0056] Reference is further made to the fact that the previously described method may also be carried out when, for example, a vibration arrangement is operable in more than two different motion excitation operating states, so that multiple intermediate threshold temperatures may lie between the upper threshold temperature and the lower threshold temperature, which each depict a transition between motion excitation operating states with different energy inputs. This type of motion generation arrangement may also be designed so that no discrete, thus step-wise change of the energy input occurs during the transition between different motion excitation operating states, but instead a continuously variable adjustment is achieved of the energy introduced into a respective compactor roller and thus into the asphalt material. For example, this type of motion generation arrangement may be operated so that, upon dropping below the upper threshold temperature, it transitions from the previously carried out static compaction operation into a compaction operation with a maximum energy input, thus for example, a maximum excitation amplitude in a vibration arrangement or oscillation arrangement, and at a decreasing asphalt temperature, a linearly declining energy input is set, until a state of minimum energy input is reached upon dropping below the lower threshold temperature. This state of minimum energy input may, for example, correspond to a state of a deactivated motion generation arrangement, or may correspond to a state with a non-zero energy input.