Patent Application
20220136184
The present invention relates to a method for compacting asphalt material.
In order to compact asphalt material, for example in road construction, soil compactors are used, among others, which have at least one compactor roller with a motion generation arrangement assigned to the same. When the motion generation arrangement is deactivated, the asphalt material to be compacted is compacted statically by this type of compactor roller, thus by the weight load exerted by the compactor roller. When the motion generation arrangement is activated, additional energy is introduced into the compactor roller and via the same into the asphalt material to be compacted due to the excitation of the compactor roller to oscillate or due to the generation of a deflection movement of the compactor roller. The deflection movement or oscillation, generated by the motion generation arrangement, is superimposed on the rolling movement of the compactor roller during movement of a soil compactor across the asphalt material to be compacted.
This type of motion generation arrangement, provided in assignment to a compactor roller in a soil compactor used to carry out the method according to the invention, may be designed as a vibration arrangement, through which an acceleration or force is exerted on the compactor roller substantially orthogonal to a rotational axis of the compactor roller. This type of vibration arrangement may comprise in the interior of the compactor roller an unbalanced mass arrangement, with a center of mass eccentric to the unbalanced rotational axis, drivable by an unbalance drive to rotate about an unbalanced rotational axis. The unbalanced rotational axis may, for example, correspond to the rotational axis of the assigned compactor roller. In order to be able to set different operating states with different energy inputs for this type of vibration arrangement, and thus to be able to generate different vibration amplitudes in the assigned compactor roller, the unbalanced mass arrangement may comprise mass parts movable with respect to one another, so that the mass acting in the center of mass is changeable and/or the radial distance of the center of mass of the unbalanced mass arrangement to the unbalanced rotational axis is changeable. For example, to change the mass acting in the center of mass, two mass parts may assume different angular positions from one another about the unbalanced rotational axis depending on the direction of rotation of the unbalanced mass arrangement. Alternatively or additionally, to change the energy introduced into the compactor roller or into the asphalt material, the rotational speed of a respective unbalanced arrangement and thus the vibration frequency may be changed. Compactor rollers with these assigned vibration arrangements are generally designated as vibratory rollers. Soil compactors with compactor rollers with these assigned vibration arrangements are known from DE 10 2016 109 888 A1 and DE 10 2018 132 379 A1. Vibration arrangements are known from WO 2018/23633 A1 and also CN 201801803 U, which, by changing the direction of rotation, may be switched between two operating states with different positions of two mass parts of an unbalanced mass arrangement to one another, and thus masses acting in a different center of mass.
In one alternative embodiment, an oscillation arrangement may be assigned to this type of compactor roller, by means of said oscillation arrangement a periodically changing torque is generated to act on the compactor roller about its rotational axis. This type of oscillation arrangement may comprise multiple unbalanced mass arrangements, drivable by an unbalance drive to rotate about unbalanced rotational axes eccentric to the rotational axis of the assigned compactor roller. By matching the rotational movement of the unbalanced mass arrangements about the respectively assigned unbalanced rotational axes to one another, the periodically changing torque acting about the rotational axis of the compactor roller is generated in the circumferential direction. In these types of oscillation arrangements as well, each unbalanced mass arrangement may comprise mass parts movable with respect to one another so that the mass acting in the center of mass and/or the radial distance of the center of mass of the respective unbalanced mass arrangement to the unbalanced rotational axis is changeable, in order to change the energy introduced into the compactor roller and thus also into the asphalt material to be compacted, or to change the oscillation amplitude generated in the respective compactor roller. For example, to change the mass acting in a respective center of mass of a mass arrangement, two mass parts may assume different angular positions from one another about the respective unbalanced rotational axis depending on the direction of rotation of the unbalanced mass arrangement. Alternatively or additionally, to change the energy introduced into the compactor roller or into the substrate, the rotational speed of the unbalanced mass arrangements and thus the oscillation frequency may be changed. Compactor rollers having these assigned oscillation arrangements are generally designated as oscillating rollers. This type of oscillation arrangement or a soil compactor with a compactor roller having an oscillation arrangement assigned to the same is known, for example, from WO 2019/063540 A1. Oscillation arrangements are known from DE 10 2017 122 371 A1 and DE 10 2015 112 847 A1, in which the oscillation torque or the amplitude of the oscillation movement is substantially continuously variable. WO 2013/013819 A1 discloses an oscillation arrangement, in which, by changing the direction of rotation, a switching between operating states with different oscillation amplitudes is achievable by displacing mass parts in unbalanced mass arrangements eccentric to the rotational axis of a compactor roller. By arranging this type of unbalanced mass arrangement centrally to the rotational axis of a compactor roller, this could be used as a vibration arrangement.
A soil compactor roller, used to carry out the method according to the invention, has at least one compactor roller with this assigned motion generation arrangement arranged generally therein, for example, a motion generation arrangement as is known from the previously listed prior art. The motion generation arrangement may be designed as a vibration arrangement or as an oscillation arrangement. A combination of a vibration arrangement and an oscillation arrangement in one and the same compactor roller may also be provided. Furthermore, a soil compactor, used to carry out the method according to the invention, may have two compactor rollers, which have the same motion generation arrangements, thus a vibration arrangement or an oscillation arrangement respectively, or have different motion generation arrangements, so that a vibration arrangement is provided in one of the compactor rollers and an oscillation arrangement is provided in the other compactor roller.
It is the object of the present [invention] to provide a method for compacting asphalt material by means of at least one soil compactor having at least one compactor roller with a motion generation arrangement assigned to the same, with which a compaction state of the asphalt material to be compacted may be achieved which is substantially unimpaired by external influences.
According to the invention, this problem is solved by a method for compacting asphalt material by means of at least one soil compactor having at least one compactor roller with a motion generation arrangement assigned to the same, comprising the measures:
In the method according to the invention, it may be guaranteed by suitable adjustment of the upper threshold temperature or the lower threshold temperature, depending on the circumstances which influence the cooling behavior of the asphalt material, that sufficient time is available for the compacting measures to be carried out in the course of the method. In particular, it is ensured by adjusting the upper threshold temperature or the lower threshold temperature that a compaction with an activated motion generation arrangement is prevented in a state of the asphalt material, in which this is not suitable or logical. Further, by adjusting the upper threshold temperature or the lower threshold temperature depending on surroundings conditions, the temperature window, defined between these threshold temperatures, which takes into account the fact that the asphalt material gradually cools down, corresponds to a time window that provides sufficient time in order to be able to compact the asphalt material using an activated motion generation arrangement, for example, according to a compaction plan provided for this, between these threshold temperatures. A state may thus be avoided, in which this time window is too short, and thus the provided compaction plan may not be processed or there is a risk that an operator of a compactor makes mistakes in the operation of the soil compactor, due to the resulting time pressure.
An increased precision in the consideration of surroundings conditions during compaction of asphalt material may be achieved in that 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.
If 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, then a factor substantially influencing the gradual cooling down of the asphalt material may be taken into consideration.
In order to maintain the time window to be as large as possible for processing the asphalt material with an active motion generation arrangement, while taking the surroundings temperature into consideration, it is proposed that the upper threshold temperature is increased at a decreasing surroundings temperature, and/or that the lower threshold temperature is decreased at a decreasing surroundings temperature.
Another parameter substantially influencing the cooling behavior of asphalt material is wind speed. Therefore, according to the invention, the upper threshold temperature and/or the lower threshold temperature may be set depending on a wind speed as the surroundings parameter influencing the cooling behavior of the asphalt material to be compacted.
In order to also maintain the available time window to be as large as possible for carrying out a compaction process with an active motion generation arrangement, while taking the wind speed into consideration, it may be provided that 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.
The asphalt material to be compacted may be 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. Therefore, this may also primarily be carried out, since, at an asphalt temperature above the upper threshold temperature, the asphalt material is statically compacted according to the method according to the invention and therefore, this is already compacted to an extent that, upon reaching or dropping below the upper threshold temperature, and thereby at an always still comparatively warm asphalt material, the activation of a motion generation arrangement does not disadvantageously influence the structure of the asphalt material, but instead may actually cause further compaction.
In order to be able to use the state, in which the asphalt material has a sufficient, yet not too high flowability, to optimally introduce energy, it is proposed that, 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 with a smaller energy input.
For example, it may be provided that 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 smaller energy input at an asphalt temperature lying below the at least one intermediate threshold temperature.
This may be achieved in a structurally easy to realize embodiment of a soil compactor used to carry out a method according to the invention, in that the motion generation arrangement is operable in two, that is exactly or only two motion excitation operating states with different energy inputs, and that the motion generation arrangement is operated in the motion excitation operating state with a higher energy input at an asphalt temperature lying above the intermediate threshold temperature, and is operated in the motion excitation operating state with a lower energy input at an asphalt temperature lying below the intermediate threshold temperature.
In order to be able to see the cooling behavior of the asphalt material to be compacted or the circumstances influencing the same, also when switching between different motion excitation operating states, it may further be provided that 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.
For example, the intermediate threshold temperature may be set depending on the surroundings temperature as the surroundings parameter influencing the cooling behavior of the asphalt material to be compacted, wherein this may proceed such that the intermediate threshold temperature is decreased at a decreasing surroundings temperature.
Alternatively or additionally, the intermediate threshold temperature may also be set depending on the wind speed as the surroundings parameter influencing the cooling behavior of the asphalt material to be compacted. For example, the intermediate threshold temperature may be decreased at increasing wind speed.
In one alternative embodiment type of a soil compactor or a compactor roller, the motion generation arrangement assigned to the same may be operable with an energy input that is continuously variable between a minimum energy input and a maximum energy input. This enables a finely metered adjustment of the energy input to the changing degree of compaction or to the changing temperature of the asphalt material. For example, this continuous change of the energy input may be achieved in that two mass parts of an unbalanced mass arrangement are continuously displaced with respect to one another by an assigned actuator in order to thus correspondingly continuously change the position of the center of mass or the mass acting in the center of mass of this type of unbalanced mass arrangement.
In order to be able to introduce the energy necessary to achieve the desired degree of compaction of the asphalt material in this type of embodiment during the cooling down of the asphalt material, it is proposed that, for an asphalt temperature lying at or in the range of the upper threshold temperature, the motion generation arrangement is operated with 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 minimum energy input. The energy input may be changed between these two states, thus the state with the maximum energy input and the state with the minimum energy input, for example, linearly.
In this context, reference is made to the fact that, in the meaning of the present invention, a motion generation arrangement is then in a motion excitation operating state with maximum energy input, for example, when a maximum motion amplitude is generated at the assigned compactor roller, and/or the force or acceleration or the amplitude thereof acting on the compactor roller is maximal. Equally, in the meaning of the present invention, a motion generation arrangement is, for example, in a motion excitation operating state with minimum energy input, when the induced motion amplitude or the force or acceleration or amplitude thereof acting on the compactor roller is zero, or a minimal value other than zero when the motion generation arrangement is operated with a non-zero minimum value of the energy input. In this respect, a motion excitation operating state with a minimum energy input of zero may correspond to a deactivated state of a motion generation arrangement.
The at least one motion generation arrangement, assigned to a compactor roller, may be a vibration arrangement. Furthermore, the at least one motion generation arrangement, assigned to a compactor roller, may be an oscillation arrangement.
If the motion generation arrangement [is] a vibration arrangement, it is particularly advantageous to induce the change of the energy input primarily or exclusively by changing the amplitude of the vibration to be generated or the deflection movement of a compactor roller, while the vibration frequency, for example, may be maintained substantially constant, or it may be changed to adjust to the movement speed of a soil compactor across the asphalt material to be compacted.
Furthermore, at least one soil compactor used to carry out the method according to the invention may have two compactor rollers, wherein a vibration arrangement is assigned to each compactor roller. It may also be provided that, at least one soil compactor used to carry out the method according to the invention may have 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.
The present invention is subsequently described in detail with reference to the appended figures. As shown in:
In
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.
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.
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.
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.
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
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.
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.
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.
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.
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
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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.
The consideration of different parameters, to be take into consideration in the cooling behavior or asphalt material A, previously described with respect to
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.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 128 842.5 | Nov 2020 | DE | national |
