SOIL-COMPACTING MACHINE HAVING AN ELECTRIC MOTOR AND METHOD FOR OPERATION

Abstract

The present invention relates to a ground compaction machine for compacting a ground, in particular a tandem roller, a single-drum roller, a rubber-wheeled roller or a trench roller, comprising a machine frame, at least one travel unit with a wheel or a roller drum, a travel drive for driving the travel unit, and a steering drive for adjusting the traveling direction of the ground compaction machine, the ground compaction machine comprising at least one electric motor. The present invention also relates to a method for operating a ground compaction machine.

Claims

1. A ground compaction machine for compacting a ground, comprising: a machine frame; at least one travel unit with a wheel or a roller drum; a travel drive for driving the travel unit; and a steering drive for adjusting the traveling direction of the ground compaction machine, wherein the ground compaction machine comprises at least one electric motor.

2. The ground compaction machine according to claim 1, wherein the ground compaction machine comprises at least one of the following features: the at least one electric motor is configured to drive the travel drive and/or the steering drive; the travel drive comprises an electric motor and is operated exclusively electrically; the steering drive comprises an electric motor and is operated exclusively electrically; and/or the ground compaction machine comprises a vibratory drive configured to excite a vibration at the wheel or roller drum, the vibratory drive comprising an electric motor and being operated exclusively electrically.

3. The ground compaction machine according to claim 2, wherein the vibratory drive with the electric motor is arranged inside the wheel or the roller drum.

4. The ground compaction machine according to claim 2, wherein the vibratory drive comprises an electric brake configured to shorten a coast-down time of the vibratory drive and to recover electric energy during braking.

5. The ground compaction machine according to claim 4, wherein the electric brake comprises a capacitor configured such that the capacitor is chargeable during braking and the stored energy can be used to start the vibratory drive.

6. The ground compaction machine according to claim 2, wherein the vibratory drive comprises a hydraulic energy storage device configured to shorten a coast-down time of the vibratory drive and to recover hydraulic energy during braking.

7. The ground compaction machine according to claim 1, wherein the entire ground compaction machine is configured such that the ground compaction machine can be operated exclusively electrically via electric motors.

8. The ground compaction machine according to claim 1, wherein the at least one electric motor is a synchronous motor and/or has water cooling.

9. The ground compaction machine according to claim 1, wherein the ground compaction machine comprises at least two electric energy storage devices arranged separately from each other at different positions on the ground compaction machine.

10. The ground compaction machine according to claim 9, wherein the electric energy storage devices are shock-resistant and/or are arranged on the ground compaction machine in a vibration-damped manner.

11. The ground compaction machine according to claim 9, wherein at least one electric energy storage device is arranged inside the wheel or the roller drum.

12. The ground compaction machine according to claim 1, wherein soldered connections of electric contacts for contacting the electric energy storage devices or their cells among each other, comprise an elastic solder.

13. The ground compaction machine according to claim 1, wherein the ground compaction machine comprises at least one of the following features: solar cells are provided on a roof of an operator platform and/or on a hood of the ground compaction machine which are configured to charge the at least two electric energy storage devices; a mobile energy source, is provided which is configured to charge the at least two electric energy storage devices; and/or a connector is provided which is configured such that an external power source can be connected to the ground compaction machine.

14. A method for operating a ground compaction machine according to claim 1, comprising the step of: driving at least one travel unit and/or the steering and/or a vibratory drive of the ground compaction machine via an electric motor.

15. The method according to claim 14, characterized by at least one of the following steps: exclusively driving the entire ground compaction machine via electric motors; exciting a vibration in a wheel or a roller drum via an electric motor arranged inside the wheel or inside the roller drum; operating an electric motor inside the wheel or the roller drum using an electric energy storage device also arranged inside the wheel or inside the roller drum; braking a vibratory drive inside the wheel or the roller drum via an electric motor with recovery of electric energy during braking; and/or charging at least one electric energy storage device via recovery of electric energy during braking and/or solar cells and/or a fuel cell and/or another external power source.

16. The ground compaction machine according to claim 1, wherein the ground compaction machine comprises one of a tandem roller, a single-drum roller, a rubber-wheeled roller or a trench roller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be explained in more detail below by reference to the embodiment examples shown in the figures. In the schematic figures:

[0031] FIG. 1 shows a ground compaction machine configured as a tandem roller;

[0032] FIG. 2 shows a ground compaction machine configured as a single-drum roller;

[0033] FIG. 3 shows a ground compaction machine configured as a rubber-wheeled roller;

[0034] FIG. 4 shows a ground compaction machine configured as a trench roller;

[0035] FIG. 5 is a flow chart of the method; and

[0036] FIG. 6 shows a ground compaction machine configured as a lightweight tandem roller.

[0037] Like components or components acting in a like manner are designated by like reference numerals in the figures. Recurring parts are not designated separately in each figure.

DETAILED DESCRIPTION OF THE INVENTION

[0038] FIGS. 1 to 4 and 6 show ground compaction machines 1 according to the present invention, with FIG. 1 illustrating a tandem roller, FIG. 2 illustrating a single drum roller, FIG. 3 illustrating a rubber-wheeled roller, FIG. 4 illustrating a trench roller, and FIG. 6 illustrating a lightweight tandem roller. Although some of the figures show, for example, exhaust systems or exhausts, these figures obviously also schematically illustrate those embodiments in which combustion engines are dispensed with. The ground compaction machines 1 may comprise a machine frame 3 and travel units 6, which are configured as roller drums 5 or as wheels 7. During working operation, the ground compaction machines 1 travel in working direction a over a ground 8 to be compacted using the travel units 6. The working direction a is in this case selected as the forward direction, although the ground compaction machines 1 can obviously also compact the ground 8 in reverse, i.e., against the working direction a. The ground compaction machines 1 of FIGS. 1 to 3 also have an operator platform 2 in which an operator may be located to control the ground compaction machine 1. The trench roller of FIG. 4, on the other hand, does not have an operator platform 2 as it is a remote-controlled unit.

[0039] Travel drives 4 are provided on the travel units 6 for driving the travel units 6 and thus for locomotion of the ground compaction machines 1. For example, each travel unit 6 may be provided with a travel drive 4 provided for that travel unit 6. Moreover, steering drives 9 are provided on each of the steerable travel units 6 of the tandem roller according to FIG. 1 and the rubber-wheeled roller according to FIG. 3, which drive a steering movement of the travel units 6 in accordance with the control commands of an operator. The single-drum roller according to FIG. 2 and the trench roller according to FIG. 4, on the other hand, have an articulated joint via which the ground compaction machine 1 is steered. In these machines, the steering drive 9 is located at the articulated joint and drives a swiveling of the front and rear machine parts and, in particular, of the travel units 6 for steering the ground compaction machine 1. Moreover, vibratory drives 16 are typically provided inside the roller drums 5 of the ground compaction machines 1, which are configured to rotate vibration exciters that excite vibration of the roller drums 5, thereby improving compaction of the ground 8.

[0040] Typically, all of the travel drive 4, the steering drive 9 and the vibratory drive 16 are hydraulic drives, such as hydraulic motors, which are operated by a hydraulic pump located elsewhere on the ground compaction machine 1. According to a first embodiment of the present invention, these hydraulic pumps are now driven by at least one electric motor 11. Said at least one electric motor 11 is supplied with electric energy by an internal combustion engine, in particular a diesel internal combustion engine, via a generator, for example. According to one embodiment of the present invention, an electric energy storage device 10 is interposed between the generator and the at least one electric motor 11, which is charged by the generator and which supplies the electric motor 11 with electric energy. In this embodiment, the internal combustion engine can always be operated at the same, preferably optimum, power point and constantly charge the electric energy storage device 10 via the generator. Power peaks incurred at the electric motor 11 are compensated for by the energy stored in the electric energy storage device, so that the speed of the internal combustion engine does not need to be changed throughout working operation. This can significantly improve operational efficiency of the internal combustion engine.

[0041] According to an alternative embodiment of the present invention, the ground compaction machine 1 does not have an internal combustion engine, i.e., is configured without an internal combustion engine. For operating the at least one electric motor 11, at least one, in particular multiple, electric energy storage devices 10 are provided, which are configured, for example, as rechargeable accumulators or batteries. In this embodiment, too, the at least one electric motor 11 drives at least one hydraulic pump, which in turn supplies hydraulic energy to the likewise hydraulic travel drive 4, the steering drive 9 and the vibratory drive 16.

[0042] According to another embodiment of the present invention, the ground compaction machine 1 no longer has a hydraulic system, i.e., operates without hydraulics or a hydraulic system. In this case, the travel drive(s) 4, the steering drive(s) 9, and the vibratory drive(s) 16 each may comprise an electric motor 11 that performs the function of the respective drives. Thus, in this case, the electric motor 11 replaces the conventional hydraulic motor of the hydraulic system. The electric motor 11 therefore directly drives, for example, the rotation of the travel units 6, the steering movement of the steering drive 9 and the vibration exciter of the vibratory drive 16. In a first variant of this embodiment, an internal combustion engine is nevertheless still present, which provides the electric energy for the electric motor(s) 11 via a generator with interposition of an electric energy storage device 10. In a second and preferred variant of this embodiment, however, the ground compaction machine 1 is configured without hydraulics or an internal combustion engine. It therefore has neither an internal combustion engine nor a hydraulic system. All functions of the ground compaction machine 1 are performed by the least one electric motor 11 and, in particular, multiple electric motors 11. In this manner, the variety of parts of the ground compaction machine 1 is significantly reduced, which simplifies manufacturing and maintenance. Dispensing with an internal combustion engine and also dispensing with the hydraulic system makes considerable installation space available, which can be used to arrange electric energy storage devices 10.

[0043] It is particularly advantageous if the entire installation space made available on the ground compaction machine 1 is used for the arrangement of electric energy storage devices 10. For example, a plurality of electric energy storage devices 10 of different shapes and different sizes may be arranged at different positions on the ground compaction machine 1, for example in the storage space conventionally used as the engine compartment and/or also, for example, in the interior of the roller drum 5. By using electric energy storage devices 10 of different shapes, the shape of the electric energy storage device 10 can be adapted to the particular mounting location. Even angled, flat or small open spaces can thus be utilized to an optimum extent. For this purpose, for example, individual cells of the accumulators are arranged differently to each other and are soldered together. To increase the shock resistance of the electric energy storage device 10, a flexible or elastic solder is used and/or current-conducting elastic connecting elements are used for the current-conducting connection of individual battery cells, which have, for example, an elastic polymer and current-conducting particles dispersed therein.

[0044] The vibratory drive 16 typically drives a vibration exciter comprising rotating imbalance masses which, by their rotation, excite a vibration in the roller drum 5. When the vibratory drive 16 is switched off, the imbalance masses typically coast down for a longer time due to their inertia. In this case in particular, it is therefore advantageous to provide an electric brake 12 which, on the one hand, reduces the coast-down time of the vibratory drive 16, i.e., brakes the vibratory drive 16 or the imbalance masses as soon as the vibration operation has been switched off, and, on the other hand, recovers electric energy from the coast-down rotation of the imbalance masses. For example, the electric brake 12 is implemented such that the electric motor 11 used to drive the vibratory drive 16 also acts as a generator which recovers electric energy from the rotation of the imbalance masses and feeds it into the electric energy storage device 10. In this manner, the vibration exciter comes to a stop more quickly and operation is made more economical overall thanks to the recovered electric energy.

[0045] For further energy generation, solar cells 13 in the form of solar panels are preferably provided on the ground compaction machine 1. They are located, for example, on the roof of the operator platform 2 or at other locations on the external cladding of the ground compaction machine 1, for example on one or more hoods. Via the solar cells 13, the electric energy storage devices 10 can be charged during the entire working operation of the ground compaction machine 1, provided, of course, that work is carried out in daylight.

[0046] Moreover, a connector 15 for an external power source is provided on the ground compaction machine 1. The connector 15 on the ground compaction machine 1 may be in the form of a socket or a charging cable, for example. Via a complementary socket or a complementary charging cable, the ground compaction machine 1 can be connected to the general power grid via the connector 15, for example, via which the electric energy storage devices 10 can then be charged. Alternatively, it is also possible, for example, to use the connector 15 to connect the ground compaction machine 1 to an energy source, for example a fuel cell 14, from which it can be charged. In the shown embodiment examples of FIGS. 1 to 4, the fuel cell 14 together with its hydrogen tank is configured as part of a charging station 23, although the charging station may also comprise other energy sources. On the one hand, the charging station 23 has a receptacle for the fuel cell 14 and its hydrogen tank, so that the hydrogen tank, in particular, is shielded from environmental influences. In addition, the charging station has a device complementary to the connector 15 of the ground compaction machine 1, so that the charging station 23 can be electrically contacted with the ground compaction machine 1 such that the fuel cell 14 charges the electric energy storage devices 10 of the ground compaction machine 1. The charging station 23 is configured, in particular, as a mobile charging station and can be moved by an operator, for example manually. For this purpose, the charging station 23 also has wheels, for example.

[0047] FIG. 5 shows the flowchart of the method 17. The method 17 starts with driving 18 at least one travel unit 6 and/or the steering and/or a vibratory drive 16 of the ground compaction machine 1 via an electric motor 11. In particular, the entire ground compaction machine 1 is driven 18 via electric motors 11. This means that the ground compaction machine 1 has neither an internal combustion engine nor hydraulics or a hydraulic system. This step is followed by exciting 19 a vibration in a wheel 7 or a roller drum 5 via an electric motor 11. The electric motor 11 is arranged, in particular, inside the wheel 7 or the roller drum 5. Operating 20 this electric motor 11 is, in particular, likewise performed by an electric energy storage device 10 arranged inside the wheel 7 or inside the roller drum 5. Braking 21 of a vibratory drive 16 inside the wheel 7 or inside the roller drum 5 is likewise performed via an electric motor 11, in particular with recovery of electric energy during braking 21. During working operation or also between working processes, charging 22 of at least one electric energy storage device 10 is performed via recovery of electric energy during braking and/or via solar cells 13 and/or via a fuel cell 14 and/or via another external power source. In addition, replaceable electric energy storage devices 10 may also be used, for example, so-called suitcase batteries. These may be charged in an external charging station 23 while the ground compaction machine 1 resumes operation with replaced electric energy storage devices 10. In this manner, downtimes for charging the electric energy storage devices 10 are avoided. All in all, therefore, the present invention makes it possible to operate the ground compaction machines 1 in an economical manner that also meets modern requirements regarding pollutant and noise emissions, and either reduces or even completely avoids the use of fossil fuels.

[0048] FIG. 6 shows a ground compaction apparatus 1 configured as a lightweight tandem roller. This class of ground compaction machines is characterized by a total weight of less than 5 t and is particularly suitable for the application of the concept described above. Generally, reference is made to the preceding description of the ground compaction machine 1. An essential characteristic of the lightweight tandem roller is, in particular, the structure consisting of a front frame 3a and a rear frame 3b, which are connected to one another in a manner known per se by means of an articulated joint. The operator platform 2, comprising a platform floor 2a, a steering column 2b and an operator seat 2c, is arranged on the rear carriage 3b. The platform floor 2a is located approximately at the height of the maximum vertical extension H (“upper apex”) of the two drums 6 or at the height of the highest point of one of the two drums 6, determined starting from the underlying ground 8 in the vertical direction to the upper apex of the drum 6 standing on the underlying ground. It is emphasized that the installation space within the machine frame 3 in the front carriage 3a and/or in the rear carriage 3b, which is below a virtual horizontal boundary line running through the maximum vertical extent H or the upper vertex of at least one of the two drums 6, can be used for at least partial and, in particular, at least complete accommodation of an electric energy storage device 10 (more specifically the electric energy storage devices 10b in the front carriage and 10c in the rear carriage). The special characteristic of the electric energy storage device 10c is that it is arranged on the rear carriage, in particular directly, below the platform floor 2a. The energy storage device 10b, on the other hand, is positioned in the front carriage. The energy storage device 10b and/or the energy storage device 10c is/are arranged in the respective region of the front carriage and/or the rear carriage that lies between the two drums in the traveling direction and below the maximum vertical extension of one of the two drums 6.

[0049] The tandem roller further comprise a hood 24 on the front carriage. Said hood can be swung open from the closed position shown in FIG. 6 to an open position. An electric energy storage device 10a arranged substantially above the virtual horizontal described above is arranged under the hood 24 as a supplement or alternative to the two energy storage devices 10b and 10c. The capacity of the latter is larger than that of the two energy storage devices 10b and/or 10c, but it may also comprise multiple subunits that can be replaced independently of one another. The hood 24 in this case provides for optimum access.

[0050] While various aspects in accordance with the principles of the present invention have been illustrated by the description of various embodiments, and while the embodiments have been described in considerable detail, they are not intended to restrict or in any way limit the scope of the present invention to such detail. The various features shown and described herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The present invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope of the general inventive concept.