EP3861170A1

EP3861170A1 - Method for controlling a ground compaction machine and ground compaction machine

Info

Publication number: EP3861170A1
Application number: EP19786719.5A
Authority: EP
Inventors: Manfred Darscheid
Original assignee: Bomag GmbH and Co OHG
Current assignee: Bomag GmbH and Co OHG
Priority date: 2018-10-04
Filing date: 2019-09-30
Publication date: 2021-08-11
Anticipated expiration: 2039-09-30
Also published as: EP3861170B1; WO2020069769A1; DE102018007825A1

Abstract

The invention relates to a method (22) for controlling a ground compaction machine (1), in particular for preventing compaction flaws, comprising the steps of: exciting (23) a vibration at a vibration frequency (f) in at least one compaction wheel (5) by means of a excitation means (13), advancing (24) the ground compaction machine (1) over ground (8) to be compacted at a movement speed (v), and modifying (28) the movement speed (v) and/or the vibration frequency (f) by determining and monitoring (25) the number of vibration impacts for each route covered (IPF) from the travel speed (v) and the vibration frequency (f), comparing (26) the determined number of vibration impacts for each route covered (IPF) with predefined limit values (IPF_max, IPF_min, IPF_end), and reducing (27) the vertical vibration amplitude (A) of the compaction wheel (5) when at least one of the limit values (IPF_max, IPF_min, IPF_end) is exceeded or not met. The invention further relates to a ground compaction machine (1) having a control unit (15) which is designed for carrying out the method (22) and/or carries out said method.

Description

METHOD FOR CONTROLLING A SOIL COMPACTION MACHINE AND SOIL

COMPRESSOR

The invention relates to a method for controlling a soil compaction machine, in particular to avoid compaction errors. In addition, the invention relates to a soil compaction machine with a control unit which is designed to carry out the method and / or carries it out.

Generic soil compaction machines are designed, for example, as road rollers, in particular special tandem rollers or single drum rollers. They are used in road and path construction to compact the subsurface, for example hot layers of asphalt or soil. For this purpose, the soil compaction machines typically have compaction bandages that are designed, for example, as roller bandages with a hollow cylindrical base body. The compression bandages can either have smooth, round surfaces, or can also be designed polygonally or with projections projecting beyond the circumference of the hollow cylindrical base body as breaker bandages. One or more compaction bandages can be provided on a soil compaction machine. It is also possible that a compaction bandage is used in combination with wheels or other running gear. The generic soil compacting machines are in particular designed to be self-propelled and comprise a drive motor, which is typically a diesel internal combustion engine. Among other things, this drives the compaction drum, so that when the soil compaction machines are in operation, the soil compaction machine travels over a soil to be compacted at a driving speed.

[0003] In order to increase the compaction performance of the generic soil compaction machines, typically a vibration is excited with at least one vibration frequency a compaction bandage by means of an excitation device. The excitation device is also referred to as a vibration exciter and comprises, for example, one or more circular exciters and can in particular be designed as a directional oscillator. By exciting a vibration on the compaction drum, the compaction performance can be increased many times compared to simply crossing the soil compaction machine over the soil to be compacted. A generic excitation device is known for example from the applicant's EP 2 1 72 279 A1.

In the work of the soil compaction machines there is often a change in the driving speed and / or the vibration frequency. This can lead to undesired effects or even compaction errors. If, for example, the driving speed is reduced while the vibration frequency remains the same, the compaction drum performs an increased number of vibrations due to the vibrations over a shorter distance. In this way, compaction is more intensive on this shorter route than if the roller were traveling faster at the same vibration frequency. This goes so far that the roller literally presses dents into the soil to be compacted at too slow speed and / or particles in the substrate material to be compacted are appreciably destroyed and thereby reduced. If, on the other hand, the soil compacting machine runs too fast at a given vibration frequency, relatively few vibrations are carried out over a long distance, which means that the individual vibrations or impacts are too far apart. This can lead to the formation of waves in the ground. The problem with this is that it is hardly possible to compensate for these bumps once they have arisen. Even if the affected areas are crossed several times, it cannot always be ensured that the compaction errors have been eliminated. This is made even more difficult by the fact that too much compression is disadvantageous, so that it is not possible to drive over the affected area as often as desired. During the compaction work, the operator of the soil compaction machine must devote a large part of his attention to ensuring that no compaction errors occur. This distracts him from the actual compaction work.

This problem occurs in particular in hybrid systems, which are used more and more frequently due to the increasingly strict environmental regulations. Soil compaction machines, which are designed, for example, as hydraulic or electrical hybrids, typically have a drive motor designed for lower power, which is supported during work when power peaks occur with energy from an intermediate store, for example a hydraulic pressure store or an electrical store. However, the energy contained in the buffer is not sufficient to bridge a peak in power, either because the peak power is too great or lasts too long, the requested power exceeds the maximum power provided by the drive motor. In this case, the driving speed and / or the vibration frequency of the soil compacting machine must typically be reduced. In this way, hybrid systems increasingly experience the problem described above that driving is too fast or too slow for a given vibration frequency or that the vibration frequency is too high or too low for a given driving speed.

It is therefore the object of the present invention to provide a method for controlling a soil compaction machine and a soil compaction machine in which the formation of unevenness in the soil to be compacted up to compaction errors is reliably avoided. At the same time, this should be possible with as little effort as possible for the operator of the soil compacting machine and in particular improve the use of hybrid systems.

The object is achieved with a method and a soil compaction machine according to the independent claims. Preferred further developments are specified in the dependent claims.

Specifically, the solution succeeds in a method mentioned at the outset by determining and monitoring the number of vibrations per route traveled from the speed and the vibration frequency, comparing the specific number of vibrations per route traveled with predetermined limit values and reducing the vertical vibration amplitude the compression bandage if at least one of the limit values is exceeded or fallen below. In the present case, a period of those vibrations is referred to as a vibration shock, in which the compression bandage is placed by the excitation device. A vibration shock therefore includes, for example in the case of a vibration in the vertical direction, a lowering of the compaction bandage from a neutral position downwards, then a lifting of the compaction bandage back to the neutral position and upwards beyond this with a subsequent lowering of the compaction bandage to the neutral position Position. The number of such vibration shocks per distance traveled is then specified, for example, as vibration shocks per meter or per foot and is referred to as the IPF value (from the English: “impacts per foot”). In the present case, the designation IPF value is independent of the one used Length unit is used so that the unit used in each case must be specified with concrete values.A value that indicates the vibrations per meter is therefore also referred to as the IPF value. A basic idea of the invention is therefore based on determining and monitoring the IPF value. As a result, the IPF value can be used as a control variable in the process. The number of vibration beats per distance traveled is calculated from the known variables of the driving speed and the vibration frequency. Specifically, the IPF value corresponds to the division of the vibration frequency by the driving speed. Since the driving speed and the vibration frequency are typically measured continuously, the IPF value can also be continuously determined and monitored. Knowing the IPF value makes it possible to compare the current value with a setpoint, a setpoint range or with limit values. For example, limit values can be specified, such as a maximum IPF value and a minimum IPF value, between which the currently measured IPF value, which is therefore present on the soil compacting machine, should ideally be found during work. In this area, the number of vibration shocks per distance traveled is set so that the vibration shocks applied to the soil to be compacted are far enough apart to not carry out excessive compaction at one point and are close enough to one another so that the soil is compacted uniformly takes place without waves.

If, on the other hand, this range of the permissible IPF value is left, since the current IPF value either exceeds the maximum limit value or falls below the minimum limit value, the vertical vibration amplitude of the compression bandage is reduced in the method according to the invention. The vertical vibration amplitude corresponds to the vibration component of the compaction drum that vibrates or is aligned in the vertical direction. “Vertical” here means perpendicular to an essentially flat ground. In particular, this vertical vibration or vertical vibration amplitude brings a particularly high level of compaction power into the soil, With a circular oscillator that vibrates equally strongly in all directions, the vertical vibration amplitude therefore corresponds to the current overall amplitude. With a directional oscillator, for example, the direction of the oscillation can be freely adjusted so that the oscillation can be adjusted, for example, between full vertical alignment and full horizontal alignment .. An oscillation of a directional oscillator can always be a superposition of a horizontal and a vertical vibration. In the case of such a directional oscillator, the vertical vibration amplitude always corresponds to that part of the vibration which is oriented in the vertical direction. By reducing the vertical vibration amplitude, according to the invention, a lower compaction power is achieved on the ground is applied. This prevents compaction errors, since a too strong punctiform compaction is excluded, both with too large and too small an IPF value. In the case of a directional oscillator in particular, this likewise means that it can continue to be operated at a constant frequency, as a result of which there is no need to reduce the vibration frequency and subsequently start the excitation device again. This has advantages both with regard to the drive motor, which can thereby be operated more precisely in the optimal power range, and with regard to comfort for an operator.

The inventive method is carried out for example by a control unit of the soil compacting machine. The control unit can either be formed as a separate control unit, or can be integrated, for example, in an on-board computer of the soil compaction machine. In particular, the method is carried out automatically by the control unit without an operator having to enter further control commands. However, the control unit can be designed, for example, to switch the method according to the invention on and off. Either the control unit itself or the on-board computer of the soil compaction machine therefore has a control element by means of which the method can be switched on or off. This control element can be both a switch and only part of a digital or virtual user interface. The control unit can also comprise a display device which, for example, shows an operator the current IPF value and / or the steps currently taken by the control unit as part of the method. This display device can also be implemented, for example, on a screen of the on-board computer.

In principle, the vertical vibration amplitude can be reduced with any excitation device capable of this. For example, excitation devices can be used which have different discrete stages with different vibration frequencies. These levels can then be used if the corresponding limit values are fallen short of or exceeded. It is particularly advantageous and therefore preferred that the vertical vibration amplitude is reduced continuously. This is the case, for example, with an excitation device such as that used by the applicant's "BOMAG Asphalt Manager". With such an excitation device, the present invention can be used in a particularly flexible manner. For example, an optimal range between the IPF value can be used here a maximum IPF value and a minimum IPF value can be set as limit values in which the method does not yet reduce the vertical vibration amplitude. If these limit values are exceeded or undershot, a sharp reduction in the vertical vibration amplitude does not have to occur suddenly be carried out, but for example reducing the vertical vibration amplitude are carried out, the amount by which the vibration amplitude is reduced being proportional to the exceeding or falling below the limit value by the current measured IPF value. In this way, the method adjusts the compaction performance by the vibration of the compaction bandage in a particularly flexible manner to the respective operating situation of the soil compaction machine.

It has been shown that an optimal compression, in which no reduction of the vertical vibration amplitude is necessary, for example in a range of 30-55 vibrations per meter, preferably 35-50 vibrations per meter and very particularly preferably from 40-45 Vibration shocks can occur per meter. Another preferred range is also 30-42 vibrations per meter. These values are therefore preferred, in particular also in pairs, as indicated, for the minimum and the maximum limit value of the IPF value. Preferred values for the minimum limit are therefore 25, 30, 35 or 40 vibrations per meter and for the maximum limit 55, 50, 45 or 40 vibrations per meter. If the maximum limit value is exceeded or the minimum limit value is undershot, the vertical vibration amplitude is reduced according to the invention. In the present application, the maximum limit is referred to as IPF _max , the minimum limit as IPF _min .

In an extreme case, the vertical vibration amplitude can be reduced until the vertical vibration amplitude disappears completely. In particular, it is preferred that the vertical vibration amplitude is reduced to zero when a critical limit value for the number of vibration shocks per distance traveled is exceeded or undershot. The critical limit is also referred to as IPF _{end in the} present case. Since it is provided according to the invention that the vertical vibration amplitude is reduced both when the current IPF value is too low and when the current IPF value is too high, there is both a low critical limit value, at which the vertical vibration amplitude is reduced to zero as well as a high critical limit value, when exceeded the vertical vibration amplitude is reduced to zero. The low critical limit is, for example, 30, preferably 25, particularly preferably 20, vibration shocks per meter. The high critical limit is, for example, 55, preferably 60, particularly preferably 65, vibration shocks per meter. A particularly preferred embodiment of the present invention provides that the reduction of the vertical vibration amplitude between the maximum limit value I PFmax and the high critical limit value and / or between the minimum limit value IPF _min and the low critical limit value linear between the maximum possible at the Excitation device adjustable vertical vibration amplitude and one vertical vibration amplitude of zero. Another advantage of reducing the vertical vibration amplitude to zero is that the invention then realizes an automatic shutdown in which, for example when the machine stops and is at a standstill, the vertical vibration amplitude is automatically set to zero, that is to say completely switched off . In this way, an operator can easily bring the machine to a standstill while driving and does not have to remember to switch off the vibration in order not to compact any dents in the ground. This effect also occurs in the case of reversing runs which frequently occur in the working operation of the soil compaction machines, in which the operator does not have to constantly switch the excitation device on and off as a result of the invention. This increases the ease of use of the soil compaction machine.

In the operation of the soil compaction machine it happens that power peaks occur, for example when starting the machine and when, for example, slopes or embankments are driven up. If, due to such an operating situation, more power is suddenly demanded from the soil compacting machine, it often happens that the speed and / or the vibration frequency are changed, in particular reduced, in the short term in order to meet the power requirement. In these situations, the method according to the invention can considerably simplify the control of the soil compaction machine. It is therefore preferred that the changing of the driving speed and / or the vibration frequency takes place due to an increased requested performance of the soil compacting machine. Particularly in the case of these changes, which are sometimes difficult to predict by the operator, it is particularly practical if, in case of doubt, the method automatically reduces the vertical vibration amplitude without the operator having to take any action. In this way, compaction errors can be avoided efficiently.

As already explained at the beginning, the problem of occurring power peaks and the consequent occasional overloading of the drive motor is particularly problematic in hybrid systems. It is precisely these systems which therefore benefit particularly greatly from the present invention, which ensures that no compression errors occur even when power peaks occur and the machine's reactions to a change in the driving speed and / or the vibration frequency. In a preferred embodiment, the soil compaction machine is thus designed as a hybrid, in particular an electrical or hydraulic hybrid. In particular, the soil compacting machine comprises an intermediate store, and before the change in the driving speed and / or the vibration frequency, when the requested power of the soil compacting machine is increased, additional power is released. tion through the buffer. The intermediate store can be, for example, an electrical store, such as a rechargeable battery, or a hydraulic store, for example a pressure store. The release of additional power is therefore carried out either by the release of additional electrical energy or, for example, by the release of pressurized fluid that is under pressure in the buffer store. In this way, power peaks that typically occur in FHybrid systems are to be bridged.

Often, however, the energy stored in the buffer is not sufficient to completely bridge the peak power. For example, the uphill journey takes longer than it can be maintained by the drive motor and the intermediate store under the current operating parameters. In order to fully exploit the entire potential of the hybrid system, it is preferred in this case that the driving speed and / or the vibration frequency are only changed after the energy stored in the intermediate store has been completely used up, if there is still an increased requested performance of the soil compacting machine. In this way, the vertical vibration amplitude is only then reduced by the method, as a result of which it is possible to work longer with a high vertical vibration amplitude and thus high compression performance. In this way, the method according to the invention is particularly efficient, particularly in interaction with a hybrid system.

It is also provided in a preferred embodiment of the invention that the state of charge of the buffer is also used to control the method. The state of charge of the buffer store is therefore detected by means of a suitable sensor. On the basis of the state of charge, a decision is then made, for example by the control unit, as to whether a peak power can be bridged by using the energy stored in the intermediate store or whether a reduction in the vertical vibration amplitude is necessary immediately. In particular, the transition from releasing additional power or energy from the buffer store to reducing the vertical vibration amplitude can be controlled by the control unit on the basis of the measured state of charge of the buffer store. Regardless of the state of charge of the buffer, the necessary measure is always taken to avoid compression errors.

In principle, the method can be used in such a way that only and exclusively a reduction of the vertical vibration amplitude is carried out. In other words, the vertical vibration amplitude can only be increased by the operator himself, for example using a control command. This can serve as an additional security measure, so not without the will of the Operator is compacted more suddenly again. In order to further relieve the operator, however, it is alternatively preferred that the vertical vibration amplitude be increased when the at least one limit value is again exceeded or undershot. If, for example, the currently measured IPF value is again above the minimum critical limit value or below the maximum critical limit value, the vertical vibration amplitude can be increased again from zero. The continuous adjustment of the vertical vibration amplitude between the critical limit values and the maximum or minimum limit value can be carried out essentially the other way around as the reduction already described above. In this way, the compaction performance currently applied to the soil is always adapted to the current operating situation without an operator having to intervene.

In particular, the potential of the machine is best exploited if maximum compression is carried out in the optimal range between the maximum and the minimum limit value. This means in particular that the vertical vibration amplitude is adjusted to its maximum value when the number of vibration shocks per distance traveled is in a predetermined optimal range, in particular between the limit values IPF _max and IPF _min . If the soil compaction machine is in the desired optimal range, this condition is also used for maximum compaction performance.

The inventive method reduces the vertical vibration amplitude, which is caused by the excitation device on the compaction drum. This reduction typically also reduces the power consumption of the excitation device. If, for example, only a horizontal vibrator is excited by a directional oscillator, the power consumption of the excitation device can decrease by half compared to the case in which only vertical vibrations are excited. In this way, additional power is released in the drive train of the soil compacting machine, which can then be used for other purposes. In a preferred embodiment it is provided, for example, that the power saved by reducing the vertical vibration amplitude is used to increase the driving speed and / or the vibration frequency. In this way, a slowdown of the soil compaction machine and / or a reduction in the vibration frequency can be at least partially counteracted. Overall, the speed of the soil compaction machine is reduced less strongly, for example, which in turn makes the work operation more efficient.

Here too, however, the particular efficiency of the invention when used with a hybrid system is again evident. A particularly preferred embodiment provides that the through the reduction of the vertical vibration amplitude saved power is used to charge the buffer. In particular in the case of a long-lasting peak in power, in which the energy stored in the intermediate store has already been used up, the intermediate store is correspondingly empty. If the vertical vibration amplitude then has to be reduced as a result of a change in the driving speed and / or the vibration frequency on the basis of the current IPF value then measured, the power released can at least be used to charge the buffer store. In this way, a charged buffer is available again at the next peak performance, so that the efficiency of the hybrid system increases.

Especially starting and braking the excitation device can be disruptive in the working operation of the soil compacting machine. It is therefore preferred that the vibration frequency of the vibration of the at least one compression bandage is kept substantially constant. In particular, this is kept constant. Essentially, in the present case means that there may be operational fluctuations, but no externally induced or controlled changes to the vibration frequency are made. In this way, the excitation device can always be driven in the same way and, for example, it does not have to be coupled when reversing. Of course, at the same time, this means that the driving speed is reduced in order to bridge these during peak loads. In the method according to the invention, therefore, preferably only the driving speed is changed and the vibration frequency is kept constant. Alternatively, it is also possible to change the vibration frequency and in particular the vibration frequency and the driving speed. The vibration frequency can also be reduced in order to bridge a power peak. However, care must be taken to ensure that the vibration frequency is not reduced to the resonance frequency of the drum, so that the machine is not damaged. Even if the vibration frequency changes, it is therefore preferred that it is changed only in such a way that the excitation device is operated in a supercritical manner in working mode. In particular, it is preferred to reduce the vibration frequency if the vertical vibration amplitude is essentially zero, that is to say the vibration is only oriented horizontally, for example. In this case, reducing the vibration frequency can also reduce wear. In this case, the damage otherwise to be feared for the work result is also less. By changing the vibration frequency and / or the driving speed, the control unit can regulate and control compliance with the optimal IPF value in a particularly flexible manner.

In addition, the present invention also makes it possible to always operate the drive motor as close as possible to its optimum power point, since one possibility is given is to overcome load peaks without changing a power output by the drive motor. It is therefore preferred that an output or the speed of a drive motor of the soil compacting machine is kept substantially constant. In particular, the power output or the speed is kept constant. Here, too, essentially means that, although operational fluctuations are possible, for example, no externally induced or controlled changes in the power output or the speed are carried out. Such optimal operation of the drive engine extends its service life and at the same time reduces fuel consumption.

The object mentioned above is also achieved by a soil compaction machine with a control unit which is designed to carry out the method according to the invention and / or carries it out. The method according to the invention is therefore used to control the floor milling machine, which is designed for this use and comprises at least one control unit which is able to carry out the method. All of the features, effects and advantages described above for the method also apply in a figurative sense to the soil compacting machine according to the invention. At the same time, all of the features, effects and advantages described for the soil compaction machine also apply to the method according to the invention. It is therefore only to avoid repetition that reference is made to the other statements.

The soil compacting machine comprises in particular a machine frame, a drive motor, at least one compaction drum, an excitation device for exciting a vibration on the compaction drum with a vibration frequency, and a frequency sensor for measuring the vibration frequency and a route sensor for measuring the distance traveled. The frequency sensor and the route sensor are connected to the control unit and, in particular continuously, supply the latter with corresponding measured values of the vibration frequency and the distance traveled. These are used by the control unit when carrying out the method.

As has also been explained above, the soil compaction machine is very particularly preferably in the form of a hybrid, in particular a hydraulic hybrid, with an intermediate store. Especially with such a hybrid system, the present invention is particularly advantageous. The invention is explained in more detail below on the basis of the exemplary embodiments shown in the figures. They show schematically:

Figure 1 is a side view of a tandem roller;

Figure 2 is a side view of a single drum roller;

FIG. 3: a diagram of the drive and the control unit of a soil compaction machine;

Figure 4: the time sequence of the method with a gradual increase in the driving speed;

Figure 5: the timing of the method with a gradual reduction in Fahrgeschwin speed;

Figure 6: the timing of the process when using a hybrid system; and

Figure 7: a flow chart of the method.

The same or equivalent components are denoted in the figures with the same reference numerals. Repeating components are not identified separately in each figure.

Figures 1 and 2 show generic and inventive soil compaction machines 1. The soil compaction machine 1 of Figure 1 is designed as a tandem roller, that of Figure 2 as a roller train. The soil compaction machines 1 comprise a driver's cab 2 and a machine frame 3, and a drive motor 4, which is typically a diesel combustion engine. The drive motor 4 drives, among other things, a chassis which comprises at least one compression drum 5 fastened to the machine frame 3 via a drum holder 6. In the case of the tandem roller from FIG. 1, this has a compression bandage 5 both at the front and at the rear. The single drum compactor according to FIG. 2 has a front compacting drum 5 and comprises two wheels 7 on its rear chassis axis. In working mode, the ground compacting machine 1 is driven over the ground 8 to be compacted, for example in the forward direction a. Of course, it is also possible to compress against the forward direction a, i.e. backwards. An excitation device is arranged in at least one of the compaction bandages 5 of the soil compaction machines 1, which sets the respective compaction bandage 5 in oscillations, in particular vibrations. In this way the compaction performance is increased. In order to measure the respective vibration frequency of the compaction bandage 5, the soil compaction machines 1 have frequency sensors 33, in particular one frequency sensor 33 per compaction device. tion bandage 5. In addition, the soil compaction machines 1 are able to detect which distance they have covered. For this purpose, they have a route sensor 34. This can either determine the route from the driving speed or, for example, be designed as a rotation sensor on the wheels 7 or the compression bandages 5. In addition, the soil compaction machines 1 comprise a control unit 15, which is connected to the frequency sensor 33 and the route sensor 34. The control unit 15 is designed to carry out the method according to the invention or carries it out. In particular, the method according to the invention is carried out individually for each compaction bandage 5 or alternatively for all compaction bandages 5 of a soil compaction machine 1.

Figure 3 shows schematically the drive of the soil compaction machine 1 and its connection to the control unit 1 5. On the drive motor 4, a traction pump 9 and a vibration pump 10 are arranged. Both are driven by the drive motor 4. The traction pumps 9 are connected to the traction motor 11 by a hydraulic line 19, which drives at least one wheel 7 or at least one compaction drum 5 of the soil compaction machine 1. The vibration pump 10 is also connected via a hydraulic line 19 to a vibration motor 12, which supplies the excitation device 13 with energy via a mechanical coupling 20, so that the excitation device 13 vibrates the compression bandage 5 during operation. On the excitation device 1 3, an amplitude control 14 is also provided via a mechanical coupling 20, via which the vibration amplitude, in particular the vertical vibration amplitude of the compression bandage 5, which is caused by the excitation device 1 3, is adjustable. According to a particularly preferred embodiment, the soil compaction machine 1 is designed as a hybrid system. For this purpose, it is provided that a pump / motor unit 16 is also arranged on the drive motor 4, which is connected via hydraulic lines 19 to a charge / discharge valve 17 and via this to an intermediate store 18, for example a hydraulic pressure store. If excess power is available in the drive train of the soil compaction machine 1, the pump / motor unit 16 acts as a pump and charges the buffer store 18 via the charge / discharge valve 1 7. In the case of power peaks which exceed the power output of the drive motor 4, in contrast, in Intermediate storage 18 stored energy are released via the charge / discharge valve 1 7, so that the pump / motor unit 16 operates as a motor and introduces additional power, for example in the form of a torque, into the drive train. Power peaks can be bridged as long as the energy stored in the buffer 18 is sufficient. FIG. 3 also shows the control unit 15 and its connection to the frequency sensor 33 and to the route sensor 34. In addition, the control unit 15 is, however, also connected to other components of the drive with control lines 21. In the present case, the control lines 21 are, for example, electrical lines via which both control commands and recorded measurement values can be transported. The control unit 15 is, for example, in particular designed to measure the vibration frequency of the excitation unit 13, for example via the frequency sensor 33, and the distance traveled, for example via the route sensor 34. In addition, the control unit 15 is designed to control the amplitude controller 14 in such a way that, according to the method, it performs a reduction or an increase in the vertical vibration amplitude as a function of the measured or calculated current IPF value.

Figure 4 shows the system and its response over time with a gradual increase in driving speed v. The abscissa of all the diagrams indicated indicated the time t. The diagrams are arranged in such a way that the individual marked times along the abscissa coincide in all diagrams. This also applies to FIGS. 5 and 6. At the beginning of the sequence shown in FIG. 4, in the diagram to the left of the point in time ti, the soil compacting machine 1 is in the normal operating mode and travels over the soil 8 to be compacted at a constant driving speed v 1 3 excites an oscillation on the compression bandage 5, the vibration frequency f of which remains essentially constant throughout the entire process. In the exemplary embodiments shown, the peak power is therefore compensated for by adapting the driving speed v, as will be described below. Alternatively, however, the vibration frequency f could also be changed, either alone or together with the driving speed v. At time ti, the operator of the soil compaction machine 1 accelerates. The vehicle speed v increases until a constant, increased vehicle speed v is reached again. Because the vibration frequency f remains constant and the driving speed v is increased, the number of vibrations per distance covered, i.e. the IPF value, decreases (see diagram below). However, the IPF value is still above a minimum limit value IPF _min , so that, as shown in the diagram above, the vertical vibration amplitude A also remains constant, for example at its maximum value that can be set on the excitation device 13. At time t ₂ , the operator accelerates the soil compacting machine 1 further. This time, the driving speed v increases in such a way that, due to the constant vibration frequency f, the IPF value drops below the predetermined minimum limit value IPF _min . This happens at time t3. The control unit that determines the IPF value from the driving speed calculated v and the vibration frequency f, notices that the IPF value has fallen below the minimum limit IPF _min and therefore initiates a reduction in the vertical vibration amplitude A at time t ₃ , as shown in the top diagram. The vertical vibration amplitude A is therefore changed (in all the exemplary embodiments shown in the figures) as a function of the IPF value by the control unit. The change in the vertical vibration amplitude A is therefore slightly offset in time from the change in the IPF value and occurs later, since the vertical vibration amplitude A is regulated or controlled as a function of the IPF value. The soil compacting machine 1 is further accelerated by the operator until time t _t , until a constant driving speed v is then reached again. The reduction of the vertical vibration amplitude A by the control unit 15 is therefore also continued until the time t _t , at which the IPF value also no longer changes. Between the times t _t and t ₅ , the floor sealing machine 1 or the excitation device 13 is therefore operated with a reduced vertical vibration amplitude A. Between these, this remains essentially constant at the times. At time t ₅ , however, the soil compaction machine 1 is accelerated again. This time the acceleration goes so far that the IPF value drops below the critical limit value IPF _{end at the time} . Up to this point, the control unit 15 has continuously reduced the vertical vibration amplitude A in proportion to the drop in the IPF value. The method according to the invention is either designed such that when the critical limit value IPF _end is reached, the vertical vibration amplitude of the A becomes just zero, or the method according to the invention is designed such that the control unit 15 uses the amplitude control for 10 to control the vertical vibration amplitude A. when the critical limit value IPF _end is reached, no matter what the previous value of the vertical vibration amplitude A was. In the exemplary embodiment shown, the vertical vibration amplitude A just reaches zero when the IPF value falls below the critical limit value, in this case the low critical limit value IPF _end . Only at time t ₇ is the driving speed v of the soil compaction machine 1 reduced again by the operator, so that the IPF value at time te rises again above the critical limit value IPF _end . From this point in time, the vertical vibration amplitude A is increased again, from zero in the exemplary embodiment shown. Between the times te and te, the excitation device 13 is therefore operated with a constant vibration frequency f but with a vertical vibration amplitude A equal to zero. For example, the excitation device 1 3 only generates horizontal vibrations during this time. The increase in the vertical vibration amplitude A corresponds proportionally to the increase in the IPF value until, at time t _9, the soil compaction machine 1 was braked in such a way that the IPF value rose again above the minimum limit value IPFmin. From this point on, the vertical vibration amplitude A is increased until it is again takes its maximum value from the beginning of the process shown. The soil compaction machine 1 is in the optimal operating state and applies the maximum compaction power to the soil 8 to be compacted.

Figure 5 shows the course of a similar situation as Figure 4, wherein the case of a gradual reduction in driving speed v is shown in Figure 5. Such a reduction in driving comfort v can occur, for example, in order to bridge the power peaks of the soil compacting machine 1 that arise during working operation, for example when it has to drive up a slope. In a figurative sense, the above explanations for FIG. 4 also apply to FIG. 5, which is why only the differences are discussed. At time ti, the soil compaction machine 1 is braked in accordance with FIG. 5. However, the driving speed v remains so high that the IPF value increases, but remains below the maximum limit value IPF _max . For this reason, the slowed down compaction machine 1 is still in the optimal range, so that the vertical vibration amplitude A remains constant. Only by the time point t ₂ entering further deceleration is then at time t _3, the maximum limit value IPF _max of the IPF value is exceeded, so that here also reducing the vertical vibration amplitude A is initiated by the control unit 1. 5 Here, too, there follows an operation of the soil compaction machine 1 with a constant, reduced vertical vibration amplitude A between the times U and t ₅ , since the currently calculated IPF value is between the maximum limit value IPF _max and the critical limit value IPF _end , in particular that high critical limit. As a result of the further reduction in the driving speed v from the time t ₅ , the IPF value finally increases at the time te beyond the critical limit value IPF _end , as a result of which the vertical vibration amplitude A is set to zero. Here too, compaction errors are avoided. From the time t _? The soil compaction machine 1 is accelerated again, so that the time _falls below the critical limit value IPF _end at time te and also falls below the maximum limit value IPF _max from time t ₉ . When the critical limit value IPF _end is undershot, the vertical vibration amplitude A is increased again proportionally to the increase in the IPF value. From falling below the maximum limit value IPF _max , the control unit 15 then again sets the maximum vertical vibration amplitude A. The compaction in the optimal operating condition of the soil compaction machine 1 can then be continued.

The particularly advantageous integration of the method according to the invention in a flybrid system is illustrated in FIG. The upper four diagrams correspond to those of FIGS. 4 and 5 and show the vertical vibration amplitude A, the vibration frequency f, the driving speed v and the IPF value. In particular, the sequence shown corresponds to the case with a Reduction of the driving speed v according to FIG. 5, although the process is simplified. At the beginning of the sequence shown in FIG. 6, the soil compacting machine 1 is in normal working mode, it is traveling at a constant driving speed v and compresses the soil 8 with a constant vibration frequency f. As shown in the bottom diagram, the drive motor 4 is operated with a constant power output E or with a constant speed. The power required for the entire operation of the soil compaction machine 1, that is to say the required power L, at this point in time lies below the power output E achieved by the drive motor 4. At the time ti, the requested power L of the soil compaction machine 1 increases. The reason for this can be, for example, that the soil compaction machine 1 has to compact uphill. As long as the requested power L remains below the power output E generated by the drive motor, nothing happens for the time being. At time t2, however, the requested power L exceeds the power output E of the drive motor 4. At this time, the flybrid system of the soil compaction machine 1 is noticeable. Specifically, the intermediate storage 18 releases additional energy or power and feeds it into the drive train of the soil compaction machine 1. The power output H of the buffer store 18 increases. The additional power output H from the buffer store 18 allows the increased power requirement of the soil compacting machine 1 to be covered. For this reason, the soil compacting machine 1 can continue its operation without being affected. At time t _3, however, the energy reserves of the intermediate storage 18 approach their end and the power output H from the intermediate storage 18 decreases. From this point in time, the required power of the soil compaction machine 1 can no longer be covered by the combination of the drive motor E and the intermediate store 18. In order to maintain work, the power required must be reduced elsewhere. According to the invention, this is preferably done at the driving speed v, which is reduced from the time t _{3 in} order to absorb the increased power requirement. Since the vibration frequency f remains constant, the IPF value also increases as the driving speed v decreases. As already explained above in connection with FIG. 5, the IPF value at the time t exceeds the maximum limit value IPF _max , so that from this point in time the control unit 15 reduces the vertical vibration amplitude A, which is constant up to the time tu was held. The driving speed v is reduced until the available power is sufficient for the operation of the soil compacting machine 1. This is achieved at time t ₅ , so that the driving speed v can be kept constant from here. The rise in the IPF value therefore also ends at time t ₅ , so that the reduction in the vertical vibration amplitude A is also stopped at time t ₅ . The vertical vibration amplitude A can now remain constant. Later, the increased power requirements decrease again, for example because the floor clearing machine 1 moves from a slope to a level, so that the requested power L falls again below the power E output by the drive motor 4 at the time te. At this point in time, the vehicle speed v can then be increased again, which leads to a decrease in the IPF value and an associated increase in the vertical vibration amplitude A, as already described above.

FIG. 6 shows a further advantage of the method. As already explained above, the excitation device 1 3 consumes less power when the vertical vibration amplitude A is reduced. The power thus available can be used elsewhere on the soil compaction machine 1. For example, two different possibilities are shown in FIG. 6. On the one hand, the power that is released can be used to reduce the driving speed v of the soil compaction machine 1 less. This is shown by the dashed line in the diagram of the vehicle speed v. The dashed curve shows the course of the driving speed v when the power released by reducing the vertical vibration amplitude A is used to maintain a higher driving speed v. The solid line, on the other hand, shows the case in which the additional power is not invested in the driving speed v. By using the power released by reducing the vertical vibration amplitude A, a higher driving speed v can be set, so that the compression process as a whole becomes more efficient. As an alternative to this, however, it is also possible to use the power released by reducing the vertical vibration amplitude A to load the buffer store 18. This is also indicated in the diagram of the power output H from the buffer store 18 by the dashed line. The dashed line illustrates a loading process of the buffer store 1 8, since the dashed line runs below the zero line of the power output H running parallel to the time axis. The negative power output shown corresponds to a charging process. The intermediate store 18 is loaded over the entire period in which the vertical vibration amplitude A is reduced, since less power is required by the excitation device 13 over this entire period and the excess power is therefore available for loading the intermediate store 18. In this way, the buffer store 18 can be at least partially recharged immediately after the energy stored in it has been completely consumed, so that an at least partially charged buffer store 18 is again available at the next power peak.

FIG. 7 shows an exemplary flow diagram of the method 22 according to the invention. The method 22 comprises the excitation 23 of a vibration on a compression bandage 5 by the excitation. gereinrichtung 1 3 and the movement 24 of the soil compacting machine 1 over the soil 8. If the soil compacting machine 1 is designed as a hybrid system, power or energy can be released from an intermediate storage 18 in step 22 to bridge a power peak. For various reasons, the driving speed v and / or the vibration frequency f can change 28 in work mode, for example if the energy in the intermediate store 18 is not sufficient to completely bridge the increased power requirement of the soil compaction machine 1. Due to a change 28 in the driving speed v and / or the vibration frequency f, the current IPF value of the soil compacting machine 1 also changes, which is determined and monitored in step 25. The determined IPF value is then compared in step 26 with predetermined limit values IPF _max , IPF _min , IPF _end . If the measured IPF value lies in an optimal range between the minimum limit value IPFmi _n and the maximum limit value IPF _max , nothing happens and work continues undisturbed. If, on the other hand, the measured IPF value is below the minimum limit value IPFmin or above the maximum limit value IPF _max , the vertical vibration amplitude A is reduced 27 in the first case and the vertical vibration amplitude A increases 29 in the second case. In the case of increasing the vertical vibration amplitude A, the method 22 starts again. If, on the other hand, the vertical vibration amplitude A is reduced in step 27, the power consumption of the excitation device 13 decreases and, owing to the reduced power requirement, excess energy is available, which can be used in step 30, for example, to increase the driving speed v and / or the vibration frequency f increase or at least buffer their reduction. As an alternative to this, it is also possible to use the energy saved in step 31 to charge the buffer store 18. All in all, the present invention succeeds in efficiently preventing the occurrence of compaction errors in the working operation of the soil compaction machine 1. At the same time, virtually no operator attention is required for this, which increases the ease of use of the soil compacting machine 1. In particular when used with a hybrid system, these advantages are particularly evident.

Claims

PATENT CLAIMS

1. A method (22) for controlling a soil compaction machine (1), in particular for avoiding compaction errors, comprising the steps:

a) excitation (23) of a vibration with a vibration frequency (f) in at least one compression bandage (5) by means of an excitation device (13),

b) moving (24) of the soil compaction machine (1) over a soil (8) to be compacted at a driving speed (v), and

c) changing (28) the driving speed (v) and / or the vibration frequency (f), characterized by the

d) determining and monitoring (25) the number of vibrations per distance traveled (IPF) from the vehicle speed (v) and the vibration frequency (f), e) comparing (26) the determined number of vibrations per distance traveled (IPF) with specified limit values (IPF _max , IPF _min , IPF _end ) and

f) reducing (27) the vertical vibration amplitude (A) of the compression bandage (5) if the minimum and _maximum values (IPF _max , IPFmin, IP-

F end)

2. The method (22) according to claim 1,

characterized,

that the vertical vibration amplitude (A) is continuously reduced (27).

3. The method (22) according to one of the preceding claims,

characterized,

that the vertical vibration amplitude (A) is reduced to zero when the critical limit (IPF _end ) of the number of vibrations per distance traveled (IPF) is exceeded or fallen below.

4. The method (22) according to any one of the preceding claims,

characterized,

that the changing (28) of the driving speed (v) and / or the vibration frequency (f) is due to an increased requested power (L) of the soil compacting machine (1).

5. The method (22) according to any one of the preceding claims,

characterized,

that the soil compacting machine (1) comprises an intermediate store (18) and before the change (28) of the driving speed (v) and / or the vibration frequency (f) with an increased requested power (L) of the soil compacting machine (1) a release (18) of additional power through the buffer (18).

6. The method (22) according to claim 5,

characterized,

that only after complete consumption of the energy stored in the intermediate store (18) does the change (28) of the driving speed (v) and / or the vibration frequency (f) take place if there is still an increased requested power (L) of the soil compaction machine (1) .

7. The method (22) according to any one of the preceding claims,

characterized,

that the vertical vibration amplitude (A) is increased (29) when the at least one limit value (IPFma _x , IPFmin, IPF _end ) is again exceeded or undershot.

8. The method (22) according to any one of the preceding claims,

characterized,

that the vertical vibration amplitude (A) is adjusted to its maximum value when the number of vibrations per distance traveled (IPF) is in a predetermined optimal range, in particular between the limit values (IPF _max , IPF _min ).

9. The method (22) according to any one of the preceding claims,

characterized,

that the power saved by reducing (27) the vertical vibration amplitude (A) is used to increase (30) the driving speed (v) and / or the vibration frequency (f).

10. The method (22) according to any one of the preceding claims,

characterized,

that the power saved by reducing (27) the vertical vibration amplitude (A) is used for charging (31) the intermediate store (18).

11. The method (22) according to one of the preceding claims,

characterized,

that the vibration frequency (f) of the vibration of the at least one compression bandage (5) is kept essentially constant.

12. The method (22) according to one of the preceding claims,

characterized,

that a power output (E) of a drive motor (4) of the soil compacting machine (1) is kept essentially constant.

13. Soil compacting machine (1) with a control unit (15) which is designed to carry out the method (22) according to one of the preceding claims and / or carries it out.

14. Soil compacting machine (1) according to claim 13, with a machine frame (3), a drive motor (4), at least one compaction bandage (5), an excitation device (13) for exciting vibration on the compaction bandage (5) with a vibration frequency (f ), a frequency sensor (33) for measuring the vibration frequency (f) and a route sensor (34) for measuring the distance traveled.

15. Soil compacting machine (1) according to one of claims 13 or 14, which is designed as a hybrid, in particular special hydraulic hybrid, with an intermediate store (18).