SOIL COMPACTION MACHINE WITH ELECTRIC MOTOR AND METHOD FOR OPERATION

Description

[0001] The invention relates to a soil compaction machine for compacting soil, in particular a tandem roller, a single-drum roller, a pneumatic-tyred roller, or a trench roller. Furthermore, the invention relates to a method for operating a soil compaction machine.

[0002] Soil compaction machines of this type are primarily used in road and path construction, as well as in the construction of airfields or runways, for example at airports. They usually have a machine frame and at least one chassis. The chassis typically comprises at least one roller drum, with which the soil compaction machine rolls over the soil during operation and compacts it. The outer peripheral surface of the roller drum can be smooth or structured, as is common with so-called crusher drums, which are used, for example, to crush rock. In addition to roller drums, rubber wheels are also used for soil compaction. The elastic deformability of rubber wheels creates a kneading and rolling effect, which in particular brings about pore closure on the soil surface.To drive the chassis, soil compaction machines typically include a travel drive, for example, a hydraulic motor that rotates the roller drum or wheel. Typical soil compaction machines are articulated or pivot-steered and also have a steering drive for adjusting the direction of travel of the soil compaction machine. The steering drive is typically also a hydraulic actuator that implements control commands entered by an operator, for example, via a steering wheel or joystick. It is also known to equip soil compaction machines of this type with a vibration drive that vibrates the roller drum or wheel to increase compaction performance. The corresponding vibration drives are also typically operated hydraulically.

[0003] To provide the drive power needed to operate the machine, especially the hydraulic components, on soil compaction machines of this type, an internal combustion engine is typically used. These are usually diesel engines, which provide the necessary energy to operate all other components of the soil compaction machine. To operate smaller electrical or electronic components, such as lighting systems or the on-board computer, an alternator is typically used, which is also driven by the internal combustion engine.

[0004] However, the disadvantages of operating soil compaction machines with a diesel combustion engine have recently become increasingly apparent due to the increasing demands placed on environmental and working conditions. Due to the pollutant emissions from diesel engines, soil compaction machines are subject to increasingly strict environmental regulations. Furthermore, the high noise emissions from combustion engines are increasingly perceived as unpleasant. The fundamentally poor efficiency of combustion engines and their high fuel consumption, which is exacerbated, for example, by the fact that it is not always possible to operate the combustion engines at their optimal performance point, are also problems facing manufacturers of modern soil compaction machines.

[0005] Soil compaction machines with at least one electric motor are known, for example from WO2019 / 174897A1, WO2015 / 094023A1, EP1524367A7, and US2013 / 006483A1. CN101392492A discloses a roller for which the rotor of an electric motor is connected to the roller drum and rotates synchronously with the roller drum. The drum shell interior can be filled with water. SU1237730A1 discloses a roller with an electric motor drive. EP3128076A1 discloses a roller drum with an electric motor drive for generating an oscillation torque. Furthermore, it is known to equip a vibratory roller with a hydraulic fluid pressure accumulator, as disclosed in DE102010006993A1.

[0006] Against this background of the prior art, the object of the present invention is to further improve a soil compaction machine with an electric motor and a method for operating a soil compaction machine with an electric motor. In particular, the efficiency is to be increased and fuel consumption reduced.

[0007] This object is achieved with a soil compaction machine and a method according to the independent claims. Preferred developments of the invention are specified in the dependent claims.

[0008] For example, an electric motor can be used to drive one or more hydraulic pumps, which in turn drive hydraulic motors. In this way, hydraulic motors, for example of the travel drive or the steering drive, can be indirectly driven by an electric motor. In other words, an electric motor can be designed to drive the travel drive and / or the steering drive. This can be done indirectly, for example, by driving a hydraulic pump. The electric motor itself is driven, for example, by an internal combustion engine, such as a diesel engine, which in turn drives a generator. The generator converts the drive energy from the internal combustion engine into electrical energy, which is either used directly to drive the electric motor or temporarily stored in an electrical energy storage device, such as an accumulator or a battery.Intermediate storage of electrical energy in an electrical energy storage unit is preferred. In this case, the combustion engine can be constantly operated at its optimal power point to power the generator. Fluctuations in the energy consumption of the electric motor depending on the operating situation of the soil compaction machine are compensated for by the electrical energy storage unit. This significantly reduces the amount of fuel required by the combustion engine, as the combustion engine does not have to constantly operate at different speeds.

[0009] Alternatively, according to a preferred embodiment, the soil compaction machine is designed without an internal combustion engine. The soil compaction machine therefore does not have an internal combustion engine. The electric motor, which, for example, drives one or more hydraulic pumps to operate the other machine components, is powered by an electrical energy storage device, such as an accumulator or a battery. As already described, the electric motor is used to drive other components of the soil compaction machine, such as hydraulic consumers. For this purpose, the electric motor, in turn, drives one or more hydraulic pumps, which operate one or more hydraulic motors. These, in turn, operate the travel drive and / or the steering drive and / or the vibration drive of the soil compaction machine, as well as possibly other components.

[0010] According to the invention, the soil compaction machine comprises a vibration drive designed to excite vibration on the wheel or roller drum, wherein the vibration drive comprises an electric motor and is exclusively electrically operated. The vibration of the wheel or roller drum is thus accomplished by an electric motor and not, as described above, by a hydraulic motor. The electric motor is therefore used directly for the vibration of the wheel or roller drum. The vibration drive of the soil compaction machine thus does not require hydraulics. The drive system for the vibration drive is thus fully electric. In addition, it can be provided that the travel drive and / or the steering drive comprises an electric motor and is exclusively electrically operated.In these embodiments, the movement of the soil compaction machine via the travel drive and / or the adjustment of the direction of travel of the soil compaction machine via the steering drive is accomplished by an electric motor and not, as described above, by a hydraulic motor. Thus, the travel drive and / or the steering drive of the soil compaction machine also operate without hydraulics.

[0011] According to a particularly preferred embodiment, the entire soil compaction machine is designed such that it can be operated exclusively electrically via electric motors. It therefore comprises neither an internal combustion engine nor a hydraulic system and therefore deviates from the conventional design. The corresponding soil compaction machine according to the invention is therefore designed to be both internal combustion engine-free and hydraulically free or hydraulic system-free. All components of the soil compaction machine that require a drive are operated by an electric motor, in particular, for example, the travel drive, the steering drive, and the vibration drive. In particular, these each have their own electric motor, which is supplied with electrical energy from an electrical energy storage device. By omitting an internal combustion engine, the soil compaction machine according to the invention does not cause any pollutant emissions.Furthermore, a significant reduction in noise is achieved. The use of electric motors results in higher efficiency, so less rated power is required. Furthermore, the variety of machine parts is reduced, especially when a hydraulic system is also omitted, making both the production and maintenance of the soil compaction machines according to the invention significantly more cost-effective. Service activities such as oil or filter changes are no longer necessary. The freed-up engine compartment can be used almost exclusively as storage space for accumulators / batteries, enabling long working hours and / or a more compact machine design.

[0012] Suitable electrical energy storage devices are accumulators or batteries, in particular. Rechargeable electrical energy storage devices, in particular accumulators, are particularly preferred. For example, the electrical energy storage device can be a lithium-ion battery or a nickel-metal hydride battery (NiMH).

[0013] It is particularly advantageous if the electrical energy storage device is designed and arranged on the soil compaction machine in such a way that it can be replaced in a few simple steps and, in particular, without the need for tools. Tool-free means that at least one fastening device is provided to secure the position of the respective energy storage device, which can be loosened and tightened exclusively manually. For this purpose, for example, special slots are provided on the soil compaction machine where the electrical energy storage device(s), which are equipped with complementary connections, can be easily inserted and contacted.

[0014] It is preferred if the electrical energy storage device(s), in particular battery packs, are designed as replaceable modules whose individual weight is a maximum of 15 kg, in particular a maximum of 10 kg. This ensures that the individual modules can be conveniently replaced manually on the machine and can also be transported to and / or from the machine without special tools.

[0015] In principle, the electric motor of the vibration drive can be located anywhere on the soil compaction machine. For example, the electric motor can be connected via a gearbox to a vibration exciter located in the wheel or roller drum, driving this from outside the wheel or roller drum. According to a preferred embodiment, however, the entire vibration drive with the electric motor is located inside the wheel or roller drum. In this way, electrical energy only needs to be fed from the outside, for example via a cable, into the interior of the wheel or roller drum to operate the electric motor of the vibration drive. This, in turn, causes the vibration exciter to rotate, which causes the vibrations. In this way, the otherwise unused space inside the wheel or roller drum can be utilized.

[0016] During operation of the soil compaction machine, the vibration, and thus the vibration drive, is regularly switched on and off. Rotating unbalanced masses are usually used as vibration exciters. These usually continue to rotate long after being switched off, which is perceived as disadvantageous. A recovery system is therefore provided for the energy stored in the rotating unbalanced masses. This system improves the energy balance of the soil compaction machine and also leads to a faster stoppage of the vibration exciter after being switched off. The invention provides that the vibration drive comprises an electric brake designed to shorten the run-on time of the vibration drive and recover electrical energy during braking.This can be achieved, for example, by having the electric motor act as a generator after the vibration drive is switched off, converting the rotational energy stored in the rotating vibration masses into electrical energy and, for example, feeding it into the electrical energy storage device. This removes energy from the vibration exciter, allowing it to come to a standstill more quickly. At the same time, the energy thus recovered is available for reuse, for example, when starting up the vibration drive, which not only makes operation more economical but also protects the environment.

[0017] According to the invention, the electric brake comprises a capacitor which is designed such that it can be charged during braking and the stored energy can be used to start the vibration drive. In particular, when the vibration drive is switched on, greater forces are required to set the unbalanced masses of the vibration exciter from a standstill into rotation. Therefore, power peaks are regularly demanded from the system. In order to provide the necessary energy during these power peaks, the capacitor can be used, which is charged when the vibration drive is switched off by using the electric motor as a generator. When the unbalanced masses of the vibration exciter start up, the energy stored in the capacitor is then used to compensate for the power peak, thus enabling smooth operation overall.

[0018] According to the invention, the at least one electric motor can be an asynchronous motor or a synchronous motor. However, synchronous motors are preferred due to their smaller design. Furthermore, water-cooled electric motors are preferred over air-cooled motors because water-cooled electric motors are up to three sizes smaller than air-cooled motors. Overall, the invention therefore provides that the at least one electric motor, in particular all electric motors, is a synchronous motor or an asynchronous motor and / or has a water cooling system.

[0019] In particular, if the combustion engine and / or the hydraulic system are omitted, spaces on the soil compaction machine that would traditionally be used by these components are freed up. These spaces can advantageously be used, for example, to house the electrical energy storage unit for supplying the electric motor(s) with electrical energy. For example, by omitting the combustion engine, space is freed up in the engine compartment, which can be used to house an electrical energy storage unit. In order to increase the possible uninterrupted working time of the soil compaction machines, it is preferred if the soil compaction machine has more than one electrical energy storage unit. In order to make optimal use of the available installation space on the machine, the multiple electrical energy storage units can, for example, have different sizes and be arranged in different locations.A combination of permanently installed and replaceable energy storage devices can also be provided, in particular energy storage devices that can be exchanged without tools. According to a preferred embodiment, the soil compaction machine is provided with at least two electrical energy storage devices that are arranged separately from one another at different locations on the soil compaction machine. For example, a plurality of electrical energy storage devices of different sizes can be provided and arranged wherever installation space is available. The different sizes of the electrical energy storage devices used also allow optimal use of different sized or small free spaces. The size of the electrical energy storage devices, for example in the case of accumulators / batteries, refers to both the size and the number of cells (secondary cells). For example, individual cells can also be installed as electrical energy storage devices.In addition, individual cells can be designed in different shapes or can be combined in different shapes to form a larger electrical energy storage device. In this way, the shapes of the electrical energy storage devices can be adapted to the respective conditions of the available installation space, which is thus used as completely and optimally as possible. Particularly preferably, the soil compaction machine thus comprises at least two mutually separate energy storage devices or at least two separate modules that have different shapes and / or different storage capacities. These at least two mutually separate energy storage devices are also preferably arranged at different locations in the soil compaction machine, in particular without physical contact with one another.

[0020] During operation, soil compaction machines typically experience strong vibrations and shocks. Although the wheels or roller drums are typically vibration-decoupled from the rest of the soil compaction machine, the vibrations of the undercarriages, particularly when they are set in vibration, are nevertheless transmitted at least slightly to the rest of the soil compaction machine. To prevent such shocks and vibrations from damaging the electrical energy storage devices, it is preferred that the electrical energy storage devices be designed to be shock-resistant. Furthermore, it is preferred that the electrical energy storage devices be arranged or mounted on the soil compaction machine in a shock-resistant or vibration-damped manner. For example, the energy storage device(s) can be attached to the machine via a damping element, such as a rubber buffer.In particular, it can be provided that a bearing frame is included, which is mounted on the machine frame via damping elements and is vibration-damped relative to the machine frame by the damping elements. This bearing frame is preferably used to accommodate and support at least one energy storage device. It is preferred if all energy storage devices of the soil compaction machine are mounted on the machine frame in a vibration-damped manner via at least one such bearing frame.

[0021] In particular, in the roller drums of the soil compaction machine, a large portion of the available space is usually unused. Therefore, according to a preferred embodiment, at least one electrical energy storage device is arranged in a wheel or a roller drum. "In a roller drum" preferably means that the electrical energy storage device is located in the interior of the roller drum, for example, between the two disc discs that seal the roller drum outward along its longitudinal direction. Such an arrangement is not a problem, especially with vibration-resistant energy storage devices, even if the corresponding roller drum is vibrated by a vibration exciter. If the soil compaction machine has two roller drums, it is also preferred that an electrical energy storage device is arranged in each of the roller drums.

[0022] Soldered joints represent a particular risk for damage, particularly due to vibrations. Soldered joints are necessary to establish electrical contacts between different components, in particular between individual cells of the electrical energy storage devices or between the electrical energy storage devices and electrical cables, for example, to the electric motors. Therefore, soldered joints of electrical contacts, in particular for contacting the electrical energy storage devices or their cells with one another, can comprise an elastic solder. Such elastic or flexible solder is characterized by the fact that, thanks to its elasticity, it can withstand even strong and continuous vibrations without being damaged.Flexible solders are therefore significantly better suited for use on soil compaction machines with vibration drives than conventional solders, which can only withstand the typical stresses encountered during operation of soil compaction machines for a short time and wear out or break relatively quickly. The use of a flexible or elastic solder significantly increases the service life of soldered joints and improves their specific application in soil compaction machines with vibration drives. Additionally or alternatively, it can be provided that the individual cells of an electrical energy storage device are connected to a circuit board by means of elastic contact elements, which establishes the electrical connection between the cells. Such elastic contact elements can, in particular, comprise a composition of at least one elastic polymer and particles of an electrically conductive material.The connected cells then form the electrical energy storage device. A flexible solder can optionally be used for this purpose, which then serves as an elastic contact element. This technology is used, for example, in the CONCHIFERA system from Invenox GmbH in Garching, Germany. The invention also extends to the use of such electrical energy storage devices, in particular according to the CONCHIFERA system, in a soil compaction machine.

[0023] In addition, the present invention provides various designs for charging the electrical energy storage devices. As already mentioned, for example, an internal combustion engine that drives a generator can be used for this purpose. However, it is preferred if the internal combustion engine is dispensed with entirely. It can therefore be provided that solar cells are used to charge the electrical energy storage device. For this purpose, for example, a unit of mobile solar panels can be provided that is set up separately from the soil compaction machine on the construction site and serves as a charging station for the soil compaction machine and in particular the electrical energy storage devices. In addition, solar cells can also be arranged on the soil compaction machine itself, in particular on the outer surface of the soil compaction machine, such as the roof of the driver's cab and / or on the hood or engine hood.According to this preferred embodiment, solar cells are provided, in particular on the roof of a driver's cab and / or on a hood of the soil compaction machine, which are designed to charge the at least two electrical energy storage devices. The solar cells on the soil compaction machine itself can be used throughout the entire working operation, as long as this takes place during daylight hours, to charge the electrical energy storage devices, thus extending the maximum operating time of the soil compaction machine before a separate charging process or replacement of the electrical energy storage devices is necessary.

[0024] Both additionally and alternatively, it can be provided that a connection is provided which is designed such that an external power source can be connected to the soil compaction machine. The soil compaction machine itself therefore comprises the connection, which can be designed, for example, in the form of a socket or a charging cable. The connection is designed such that the soil compaction machine can be contacted, for example, with a power cable connected to the general power grid. For example, the soil compaction machine can be charged via a power cable or even operated directly via the power cable. This is particularly advantageous when, for example, soil is compacted inside a building, for example in a hall. In this environment, power cables are typically available which can be used for the entire work process.Furthermore, it is preferred if a charging station is provided that can be electrically connected to the connection on the soil compaction machine. The charging station can, for example, be connected to the general power grid or, for example, comprise a generator driven by an internal combustion engine. The connection of the soil compaction machine and the charging station are designed such that they can be easily connected in a few simple steps, so that the soil compaction machine or at least one of the electrical energy storage devices can be charged with electrical energy from the charging station.

[0025] Additionally or alternatively, a particularly mobile energy source, for example a fuel cell, may also be present, which is designed to charge the at least two electrical energy storage devices. The electrical energy storage devices are therefore charged from the energy stored in the hydrogen via a hydrogen fuel cell and are therefore both very efficient and particularly environmentally friendly. In particular, a mobile charging station is provided which comprises the fuel cell and a hydrogen tank and which can be contacted either with at least one of the electrical energy storage devices or with the soil compaction machine itself in order to charge them. The mobile charging station with the fuel cell can, for example, also comprise a chassis for easier transport and a protective structure to protect the fuel cell and / or the hydrogen tank from the effects of the weather and / or vandalism.In addition to the mobile charging station with a fuel cell, other energy sources can also be incorporated into the charging station. Examples include liquefied petroleum gas, methane, or other fossil or synthetic fuels. Furthermore, the charging station can incorporate solar cells or a generator, such as an internal combustion engine or wind or water-powered generator. Such a solution offers the significant advantage of being completely emission-free, or at least CO2-free, for both charging and operating modes.

[0026] The concept outlined above is particularly suitable for so-called light tandem rollers, in particular light ride-on tandem rollers. Such rollers are characterized by a total weight of less than 5 t. At the same time, such rollers preferably have a front frame and a rear frame, which are steerably connected to one another via an articulated joint. A driver's cab is preferably arranged on the rear carriage. On the front carriage, however, the at least one electrical energy storage unit is preferably positioned, ideally concealed under a pivoting engine hood to enable easy access and, at the same time, an aesthetic design together with mechanical protection. Such tandem rollers have at least one drum, typically on the front carriage, and at least one further drum or a rubber wheel set, typically comprising three or more coaxially arranged rubber wheels, on the rear carriage.According to the invention, an electrical energy-conducting transmission connection is preferably provided across the articulated joint connecting the front and rear sections of the vehicle.

[0027] Particularly for such lightweight tandem rollers, it is preferred if the at least one electrical energy storage device is arranged at least partially in a region below the maximum vertical height of the at least one drum, in particular both drums. This is possible because the at least one electrical energy storage device, in particular in the case of a multi-cell structure, can be formed into comparatively complex three-dimensional shapes and can thus be adapted in particular to installation spaces that have previously been used very little in such machines. It has now been shown that in particular the installation space below the maximum vertical height of the at least one drum becomes accessible for the use of an electrical energy storage device to accommodate this energy storage device. This simultaneously improves the machine's center of gravity, since this installation space is comparatively low.This installation space can be used to accommodate one or more electrical energy storage units on either the front end or the rear frame, or on both frame elements. Although the at least one electrical energy storage unit can be permanently installed in this area, it is ideal if at least one additional access opening is provided through which the at least one energy storage unit can be accessed and replaced from the outside, even in this frame area.

[0028] Particularly for lightweight, articulated tandem rollers, it is further preferred if, when the operator's platform is mounted on the rear carriage, the area below the foot area of ​​the driver sitting in a seat on the operator's platform is used. This area is also characterized by a comparatively low position. On the other hand, the potentially available installation space in this area is comparatively large and easily accessible, so that an electrical energy storage unit with a comparatively high storage capacity can be positioned very effectively in this area. It is further preferred if, at the same time, an installation space section is used in this area that is below the maximum vertical height of the drum (or the rubber wheel set) on the rear carriage. It is also preferred if an access hatch is provided in the floor panel of the operator's platform, which allows access to the electrical energy storage unit installed beneath this floor panel.

[0029] The solution to the problem mentioned above is also achieved with a method for operating a soil compaction machine as described above. All features, advantages, and effects of the soil compaction machine according to the invention also apply in a figurative sense to the method according to the invention, so that reference is made to the explanations regarding the soil compaction machine only to avoid repetition. The method according to the invention comprises the step of driving, in particular exclusively driving, at least one chassis and / or the steering and / or a vibration drive of the soil compaction machine via an electric motor, wherein the electric motor (11) is an asynchronous motor or a synchronous motor and / or has a water cooling system.As already described for soil compaction machines, this drive can be achieved via the electric motor, for example, by driving a hydraulic pump, which in turn drives a hydraulic motor for the traction drive or steering drive. However, it is preferred that the electric motor directly drives the movement of the chassis or steering, thus eliminating the need for a hydraulic system.

[0030] It is also preferred for the method if the entire soil compaction machine is driven exclusively by electric motors, i.e. if the soil compaction machine is operated both without an internal combustion engine and without hydraulics or hydraulic systems.As already mentioned, preferred embodiments of the method comprise all embodiments of the soil compaction machine and in particular the excitation of a vibration in a wheel or a roller drum via an electric motor, in particular arranged in the wheel or in the roller drum; and / or the operation of an electric motor in a wheel or a roller drum by an electrical energy storage device likewise arranged in the wheel or in the roller drum; and / or the braking of a vibration drive in a wheel or a roller drum via an electric motor, in particular with recovery of electrical energy during braking; and / or the charging of at least one electrical energy storage device via recovery of electrical energy during braking and / or solar cells and / or a fuel cell and / or an external power source.The method according to the invention also leads to more efficient and cleaner operation of the soil compaction machine.

[0031] The invention is explained in more detail below with reference to the exemplary embodiments shown in the figures. They show schematically: Figure 1 : a soil compaction machine designed as a tandem roller; Figure 2 : a soil compaction machine designed as a roller; Figure 3 : a soil compaction machine designed as a rubber-tyred roller; Figure 4 : a soil compaction machine designed as a trench roller; Figure 5 : a flow chart of the procedure; and Figure 6 : a soil compaction machine designed as a light tandem roller.

[0032] Identical or functionally identical components are designated by the same reference numerals in the figures. Recurring components are not designated separately in each figure.

[0033] The Figure 1-4 and 6show soil compaction machines 1 according to the invention, wherein the Figure 1 a tandem roller, Figure 2 a roller train, Figure 3 a rubber-tyred roller, Figure 4 a trench roller and Figure 6a lightweight tandem roller is illustrated. Even if exhaust systems or exhausts can be seen in some of the figures, these figures naturally also schematically illustrate the embodiments in which combustion engines are dispensed with. The soil compaction machines 1 comprise a machine frame 3 and chassis 6, some of which are designed as roller drums 5 or wheels 7. With the chassis 6, the soil compaction machines 1 move in working direction a over a soil 8 that is to be compacted. The working direction a is selected here as the forward direction, but of course the soil compaction machines 1 can also compact the soil 8 backwards, i.e., opposite to the working direction a. The soil compaction machines 1 of the Figure 1-3also have a driver's cab 2 in which an operator can stay to control the soil compaction machine 1. The trench roller of the Figure 4 on the other hand, does not have a driver's cab 2, as it is a remote-controlled device.

[0034] To drive the chassis 6 and thus for the movement of the soil compaction machines 1, travel drives 4 are provided on the running gears 6. For example, each running gear 6 can have a travel drive 4 provided for this running gear 6. In addition, the steerable running gears 6 of the tandem roller are provided with Figure 1 and the rubber-wheeled roller according to Figure 3 Steering drives 9 are provided, which drive a steering movement of the drives 6 according to the control commands of an operator. The roller train according to Figure 2 and the trench roller according to Figure 4In contrast, they have an articulated joint, via which the steering of the soil compaction machine 1 takes place. In these machines, the steering drive 9 is located on the articulated joint and pivots the front and rear machine parts and in particular the chassis 6 for steering the soil compaction machine 1. In addition, vibration drives 16 are typically provided in the roller drums 5 of the soil compaction machines 1, which are designed to set vibration exciters in rotation, which excite vibration of the roller drums 5, thereby improving the compaction of the soil 8.

[0035] Typically, the travel drive 4, the steering drive 9, and the vibration drive 16 are hydraulic drives, for example, hydraulic motors, which are operated by a hydraulic pump arranged elsewhere on the soil compaction machine 1. According to a first embodiment of the invention, these hydraulic pumps are driven by at least one electric motor 11. This at least one electric motor 11 is supplied with electrical energy, for example, by an internal combustion engine, in particular a diesel internal combustion engine, via a generator. According to a preferred embodiment, an electrical energy storage device 10 is interposed between the generator and the at least one electric motor 11, which is charged by the generator and supplies the electric motor 11 with electrical energy.With this embodiment, the combustion engine can always operate at the same, optimal power point and constantly charge the electrical energy storage device 10 via the generator. Power peaks generated by the electric motor 11 are balanced by the energy stored in the electrical energy storage device, so that the engine speed does not need to be changed throughout the entire operating period. This significantly improves the efficiency of the combustion engine's operation.

[0036] An alternative embodiment of the invention provides that the soil compaction machine 1 does not have an internal combustion engine, i.e., is designed without an internal combustion engine. To operate the at least one electric motor 11, at least one, in particular several, electrical energy storage devices 10 are provided, which are designed, for example, as rechargeable accumulators or batteries.

[0037] A further embodiment of the invention provides that the soil compaction machine 1 no longer has a hydraulic system, i.e., is operated hydraulically or without a hydraulic system. In this case, the travel drive(s) 4, the steering drive(s) 9, and the vibration drive(s) 16 each comprise an electric motor 11 that performs the function of the respective drives. 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 running gears 6, the steering movement of the steering drive 9, and the vibration exciter of the vibration drive 16.In a first variant of this embodiment, an internal combustion engine is still present, which provides the electrical energy for the electric motor(s) 11 via a generator with an interposed electrical energy storage device 10. In a second and preferred variant of this embodiment, however, the soil compaction machine 1 is designed to be both hydraulic-free and internal combustion engine-free. It therefore has neither an internal combustion engine nor a hydraulic system. All functions of the soil compaction machine 1 are performed by at least one electric motor 11 and in particular by several electric motors 11. In this way, the variety of parts of the soil compaction machine 1 is significantly reduced, which simplifies manufacture and maintenance.By omitting an internal combustion engine and also by omitting the hydraulic system, considerable installation space is freed up, which can be used for the arrangement of electrical energy storage devices 10.

[0038] It is particularly advantageous if all available installation space on the soil compaction machine 1 is used to arrange electrical energy storage devices 10. For example, it is provided that several electrical energy storage devices 10 of different shapes and sizes are arranged at different locations on the soil 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 electrical energy storage devices 10 in different shapes, the shape of the electrical energy storage device 10 can be adapted to the respective installation location. This also allows optimal use of angled, flat, or small free spaces. For this purpose, for example, individual cells of the accumulators are arranged differently relative to one another and soldered together.In order to increase the shock resistance of the electrical energy storage devices 10, a flexible or elastic solder is used and / or electrically conductive elastic connecting elements are used for the electrically conductive connection of individual battery cells, which, for example, comprise an elastic polymer and electrically conductive particles dispersed therein.

[0039] The vibration drive 16 typically drives a vibration exciter comprising rotating imbalances whose rotation excites vibration in the roller drum 5. When the vibration drive 16 is switched off, the imbalances typically continue to run for a longer time due to their inertia. In this case, it is particularly advantageous to provide an electric brake 12, which, on the one hand, reduces the run-on time of the vibration drive 16, i.e., brakes the vibration drive 16 or the imbalances as soon as vibration operation has been switched off, and, on the other hand, recovers electrical energy from the trailing rotation of the imbalances. The electric brake 12 is implemented, for example, such that the electric motor 11, which is used to drive the vibration drive 16, also acts as a generator, which generates electrical energy from the rotation of the imbalances and feeds this energy into the electrical energy storage device 10.In this way, the vibration exciter comes to a standstill more quickly and operation is made more economical overall thanks to the recovered electrical energy.

[0040] For additional energy generation, solar cells 13 in the form of solar panels are preferably provided on the soil compaction machine 1. These are located, for example, on the roof of the operator's cab 2 or at other locations on the exterior cladding of the soil compaction machine 1, for example, on one or more hoods. The solar cells 13 can be used to charge the electrical energy storage devices 10 throughout the entire working operation of the soil compaction machine 1, provided, of course, that work is carried out during daylight hours.

[0041] Furthermore, a connection 15 for an external power source is preferably provided on the soil compaction machine 1. The connection 15 on the soil compaction machine 1 can be designed, for example, in the form of a socket or a charging cable. Via a complementarily designed socket or a complementarily designed charging cable, the soil compaction machine 1 can be connected, for example, to the general power grid via the connection 15, via which the electrical energy storage devices 10 can then be charged. Alternatively, it is also possible, for example, to connect the soil compaction machine 1 to an energy source, for example a fuel cell 14, via the connection 15 and to charge it via this. In the exemplary embodiments shown, the Figure 1-4the fuel cell 14, together with its hydrogen tank, is designed as part of a charging station 23, wherein the charging station can also comprise other energy sources. The charging station 23 has, on the one hand, a receptacle for the fuel cell 14 and its hydrogen tank, so that in particular the hydrogen tank is shielded from environmental influences. In addition, the charging station has a complementary device for connecting 15 to the soil compaction machine 1, so that the charging station 23 can be electrically contacted with the soil compaction machine 1 in such a way that the fuel cell 14 charges the electrical energy storage device 10 of the soil compaction machine 1. The charging station 23 is designed, in particular, as a mobile charging station and can be moved by an operator, for example by hand. For this purpose, the charging station 23 also has wheels, for example.

[0042] Figure 5shows the flowchart of method 17. Method 17 begins with the driving 18 of at least one chassis 6 and / or the steering and / or a vibration drive 16 of soil compaction machine 1 via an electric motor 11. In particular, the driving 18 of the entire soil compaction machine 1 takes place via electric motors 11. This means that soil compaction machine 1 is designed to be free of an internal combustion engine and also free of hydraulics or hydraulic systems. This is followed by the excitation 19 of a vibration in a wheel 7 or a roller drum 5 via an electric motor 11. Electric motor 11 is arranged in particular inside wheel 7 or roller drum 5. This electric motor 11 is also operated 20 in particular by an electrical energy storage device 10 arranged in wheel 7 or roller drum 5.Braking 21 of a vibration drive 16 in the wheel 7 or in the roller drum 5 is also carried out via an electric motor 11, in particular with recovery of electrical energy during braking 21. During operation or between work steps, the charging 22 of at least one electrical energy storage device 10 takes place via the recovery of electrical energy during braking and / or via solar cells 13 and / or via a fuel cell 14 and / or another external power source. In addition, replaceable electrical energy storage devices 10 can also be used, for example so-called portable batteries. These can be charged in an external charging station 23 while the soil compaction machine 1 continues to operate with replaced electrical energy storage devices 10. In this way, downtimes for charging the electrical energy storage devices 10 are avoided.All in all, the invention therefore enables economical operation of the soil compaction machines 1, which also meets modern requirements for pollutant and noise emissions, and either reduces or even completely avoids the use of fossil fuels.

[0043] Figure 6shows a soil compaction device 1 designed as a lightweight tandem roller. This class of soil compaction machine is characterized by a total weight of less than 5t and is particularly well suited to the application of the concept described above. In principle, reference is made to the previous explanations regarding the soil compaction machine 1. What is essential for the lightweight tandem roller is the structure comprising a front frame 3a and a rear frame 3b, which are connected to one another in a conventional manner via an articulated joint. The operator's station 2, comprising an operator's station floor 2a, a steering column 2b, and a driver's seat 2c, is arranged on the rear carriage 3b. The operator's station floor 2a is located approximately at the level of the maximum vertical extension H ("upper apex") of the two drums 6 and 7.at the height of the highest point of one of the two drums 6, determined from the ground surface 8 in the vertical direction to the upper apex of the drum 6 standing on the ground surface. It should now be 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 apex of at least one of the two drums 6, can be used to at least partially and in particular to at least completely accommodate an electrical energy storage device 10 (specifically the electrical energy storage devices 10b in the front carriage and 10c in the rear carriage). The special feature of the electrical energy storage device 10c is that it is arranged on the rear carriage, in particular directly below the operator's cab 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 preferably arranged in the respective region of the front vehicle and / or the rear vehicle which lies in the direction of travel between the two drums and below the maximum vertical extension of one of the two drums 6.

[0044] The tandem roller also includes a hood 24 on the front of the vehicle. This is Fig. 6 shown closed position into an open position. An electrical energy storage device 10a, arranged substantially above the virtual horizontal described above, is arranged beneath the engine hood 24, in addition to or as an alternative to the two energy storage devices 10b and 10c. This energy storage device is preferably larger in capacity than the two energy storage devices 10b and / or 10c, but can also comprise several independently replaceable subunits. Optimal access is achieved via the engine hood 24.

Claims

1. A ground compaction machine (1) for compacting a ground (8), in particular a tandem roller, a single-drum roller, a rubber-wheeled roller or a trench roller, comprising - a machine frame (3); - at least one travel unit (6) with a wheel (7) or a roller drum (5), - a travel drive (4) for driving the travel unit (6), and - a steering drive (9) for adjusting the traveling direction of the ground compaction machine (1), - at least one electric motor (11), wherein the at least one electric motor (11) is an asynchronous or a synchronous motor and / or has water cooling, and wherein the ground compaction machine (1) comprises a vibratory drive (16) configured to excite a vibration at the wheel (7) or roller drum (5), the vibratory drive (16) comprising the electric motor (11) and being operated exclusively electrically characterized in that the vibratory drive (16) comprises an electric brake (12) configured to shorten the coast-down time of the vibratory drive (16) and to recover electric energy during braking, and in that the electric brake (12) comprises a capacitor configured such that it is chargeable during braking and the stored energy can be used to start the vibratory drive (16).

2. The ground compaction machine (1) according to claim 1, characterized in that it comprises at least one of the following features: - the travel drive (4) comprises an electric motor (11) and is operated exclusively electrically; and / or - the steering drive (9) comprises an electric motor (11) and is operated exclusively electrically.

3. The ground compaction machine (1) according to any one of the preceding claims, characterized in that the vibratory drive (16) with the electric motor (11) is arranged inside the wheel (7) or the roller drum (5).

4. The ground compaction machine (1) according to any one of the preceding claims, characterized in that the entire ground compaction machine (1) is configured such that it can be operated exclusively electrically via electric motors (11).

5. The ground compaction machine (1) according to any one of the preceding claims, characterized in that all electric motors (11) are synchronous motors and / or have a water cooling.

6. The ground compaction machine (1) according to any one of the preceding claims, characterized in that the ground compaction machine (1) comprises at least two electric energy storage devices (10) arranged separately from each other at different positions on the ground compaction machine (1).

7. The ground compaction machine (1) according to claim 6, characterized in that the electric energy storage devices (10) are shock-resistant and / or are arranged on the ground compaction machine (1) in a vibration-damped manner.

8. The ground compaction machine (1) according to any one of claims 6 or 7, characterized in that at least one electric energy storage device (10) is arranged inside the wheel (7) or the roller drum (5).

9. A method (17) for operating a ground compaction machine (1) according to any one of the preceding claims, comprising the step of: - driving (18), in particular exclusively 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), wherein the electric motor (11) is an asynchronous or a synchronous motor and / or has water cooling.

10. The method (17) according to claim 9, characterized by at least one of the following steps: - exclusively driving (18) the entire ground compaction machine (1) via electric motors (11); and / or - exciting (19) a vibration in a wheel (7) or a roller drum (5) via an electric motor (11) arranged in particular inside the wheel (7) or inside the roller drum (5); and / or - operating (20) an electric motor (11) inside a wheel (7) or a roller drum (5) using an electric energy storage device (10) also arranged inside the wheel (7) or inside the roller drum (5); and / or - braking (21) a vibratory drive (16) inside a wheel (7) or a roller drum (5) via an electric motor (11), in particular with recovery of electric energy during braking; and / or - charging (22) at least one electric energy storage device (10) via recovery of electric energy during braking and / or solar cells (13) and / or a fuel cell (14) and / or another external power source.