Soil milling machine with compressor driven by a maintenance motor and method for operating such a soil milling machine

Abstract

Soil milling machine (1) for milling soil material (7), comprising - a main drive motor (4), - a first drive train (11) driven by the main drive motor (4), and - a milling drum (9) driven by the main drive motor (4) via the first drive train (11) and rotatably mounted in a milling drum box (8) for milling soil material (7) during operation of the soil milling machine (1), characterized in that a maintenance motor (12) is provided which, separately from the main drive motor, drives a compressor (14) for providing compressed air via a second drive train (13), wherein the compressor (14) can be driven exclusively by the maintenance motor (12) via the second drive train (13) and wherein the maintenance motor (12) drives an energy converter (25), which in turn drives the compressor (14), and that the energy converter (25) provides either electrical or hydraulic energy to drive the compressor (14).

Description

[0001] The invention relates to a ground milling machine for milling soil material, comprising a main drive motor, a first drive train connected to the main drive motor, and a milling drum driven by the main drive motor via the first drive train and rotatably mounted in a milling drum housing for milling soil material during operation of the ground milling machine. The invention also relates to a method for operating such a ground milling machine.

[0002] Generic soil milling machines, in particular road milling machines, recyclers, stabilizers or surface miners, are known, for example, from EP 1 983 105 A2 and EP 1 936 033 B1. Such self-propelled soil milling machines typically comprise a machine frame or chassis, undercarriages, for example tracked drives or wheels, and an operator's platform. They also have a main drive motor, which is usually an internal combustion engine, for example a diesel engine. The essential element of a soil milling machine is a milling drum, usually mounted in a hood-shaped milling drum box, comprising a hollow cylindrical support tube, on the outer surface of which a plurality of milling tools, for example in interchangeable holders, are arranged in a known manner. During operation of the soil milling machine, the milling drum is driven by the main drive motor and rotated about a rotational axis running horizontally and transversely to the working direction.This drives the milling tools into the subsoil, milling it open. During milling, the soil milling machine moves forward in the working direction, milling away soil material. The resulting loose milled material is either left behind in the milling track or transported forward or backward in the working direction, for example, via a discharge conveyor, onto a transport vehicle.

[0003] During operation of the soil milling machine, the milling tools are repeatedly driven into the subsoil. The milling tools are subject to high wear. It is therefore often necessary to remove the worn milling tools from the milling drum and replace them with new ones. This is usually done manually by an operator who drives the milling tools out of their holders directly on the milling drum and replaces them with new ones. While the operator is busy changing the milling tools, the milling drum is usually uncoupled from the main drive motor. It is now absolutely necessary to prevent the milling drum from being accidentally coupled to the main drive motor and starting up, for example due to a coupling fault. Otherwise, the operator could be injured by the milling drum being accelerated to high speeds very quickly by the main drive motor. This risk of accident must be eliminated.

[0004] Furthermore, the milling tools are usually driven out of their holders using pneumatic tools, such as a pneumatic hammer. The compressor that supplies the compressed air for these pneumatic tools is usually powered by the main drive motor of the ground milling machine. However, the storage capacity of the accumulator is often insufficient to supply enough compressed air for a complete changeover process. It is then necessary to restart the main drive motor so that the compressor driven by the main drive motor can supply compressed air. However, the main drive motor must then be switched off again to complete work on the milling drum to avoid any danger to the operator. This is not only impractical but also unnecessarily delays maintenance work on the milling drum.In practical use, the main drive motor is therefore simply left running for convenience, whereby the operator is then exposed to a considerable risk of being injured by an unintentionally starting milling drum if the clutch is defective.

[0005] The object of the present invention is therefore to provide a ground milling machine of the type mentioned above that both reduces the risk of accidents for the operator when changing the milling bit and simultaneously enables a simple and rapid milling tool change. Furthermore, a method for operating such a ground milling machine is to be provided.

[0006] The problem is solved with a ground milling machine or a method according to the independent claims. Preferred developments are specified in the dependent claims.

[0007] Specifically, the solution for a soil milling machine of the type mentioned above, which is in particular a road milling machine, a recycler, a stabilizer, or a surface miner, is achieved by having a maintenance motor that, separate from the main drive motor, drives a compressor to provide compressed air via a second drive train. The compressor is integrated into the soil milling machine in such a way that it can only be driven by the maintenance motor via the second drive train. The first drive train, driven by the main drive motor, cannot therefore be used to drive the compressor.This allows the compressor to be operated by the maintenance motor, particularly for changing bits when the main drive motor is switched off, thus providing sufficient compressed air. At the same time, the risk of the milling drum inadvertently resuming its milling rotation during maintenance operation is eliminated by switching off the main drive motor. A "drive train" in this case refers to a functional unit between the energy source (usually an internal combustion engine) that generates the drive energy required for the drive, and the driven end consumer, such as a tracked drive, a working device, particularly the milling drum, etc. The drive train often includes, for example, mechanically acting means, such as gears, etc., for transmitting drive energy.The drive train can also be branched and, for example, comprise a drive input driven by the respective drive motor and a plurality of outputs. According to the invention, in addition to the first drive train, which is driven by the main drive motor and which, among other things, supplies the milling drum of the soil milling machine with drive energy, there is a further, second drive train whose energy source is the separate maintenance motor independent of the main drive motor. The second drive train thus draws its drive energy exclusively from the maintenance motor and not from the main drive motor. The first and second drive trains of the soil milling machine can be operated independently of one another by the main drive motor (first drive train) and the maintenance motor (second drive train).Independent means that the first and second drive trains run separately from each other until they reach the respective driven end consumer. Therefore, the main drive motor does not need to be running to operate the second drive train and all the consumers connected to it. Conversely, it is also not necessary to run the maintenance motor when the soil milling machine is in operation.

[0008] Working mode refers to the operation of the soil milling machine in which the main drive motor rotates the milling drum, causing the milling drum to mill soil material in the working direction of the soil milling machine. During working mode, the soil milling machine typically moves in the working direction with the milling drum lowered into the subsoil, milling soil material with the milling drum. Working mode is therefore essentially characterized by the movement of the soil milling machine while the milling drum simultaneously mills soil material, with the power for working mode being provided primarily by the main drive motor.

[0009] In addition to working mode, the soil milling machine can also be in maintenance mode. During maintenance mode, the soil milling machine does not move but remains in one place. During maintenance mode, for example, the milling tools on the milling drum are replaced. The milling drum is rotated slowly and step by step so that an operator can reach all milling tools on the outer surface of the milling drum in order to replace worn milling tools with new ones. The milling drum can be rotated manually or, in particular, by a drive, whereby the drive here is preferably provided by the maintenance motor when the main drive motor is switched off, in the manner described in more detail below. Maintenance mode is therefore essentially characterized by the soil milling machine not moving and the milling drum being raised from the subsoil for the milling tool to be changed.Especially during maintenance operations, compressed air is often required, especially for removing the milling bits to be replaced from their holders using a pneumatic hammer. According to the invention, the compressed air required for this is now provided by the compressor, which is driven exclusively by the maintenance motor.

[0010] This special arrangement now allows the main drive motor to remain completely switched off during maintenance operations, as the compressor, driven by the maintenance motor, ensures a continuous supply of compressed air. This significantly reduces the risk to the maintenance personnel, as it eliminates the danger of the milling drum suddenly accelerating beyond the speed suitable for milling operations, for example, due to a defective clutch, and potentially injuring the operator in front of the milling drum. The compressed air generated by the compressor can be used, for example, to drive pneumatic tools for changing milling tools. These pneumatic tools can be used, for example, to drive the milling cutters from the quick-change toolholders.Because the compressor is driven exclusively by the maintenance engine via the second drive train, the operation of the maintenance engine is sufficient during maintenance mode to continuously supply compressed air through the compressor for maintenance work. The main drive motor, on the other hand, can be switched off completely. Because the compressor is supplied with power exclusively by the maintenance engine, there is no reason at all for the operator to leave the main drive motor running during maintenance mode. Accidents caused by the milling drum starting up uncontrollably via the main drive motor are thus reliably avoided. Furthermore, fuel can be saved if the usually very powerful main drive motor is switched off during maintenance mode of the soil milling machine and only the usually lower-powered maintenance motor needs to be operated.

[0011] A basic idea of ​​the invention is therefore the provision of a main drive motor for working mode and a separate maintenance motor specifically for maintenance mode, so that the main drive motor can be completely switched off during maintenance mode. The maintenance motor and the second drive train driven by it are preferably designed such that they can drive all consumers required for servicing the ground milling machine during maintenance mode. The consumers required for servicing the ground milling machine during maintenance mode are therefore explicitly not supplied with power by the main drive motor or the first drive train, at least during maintenance mode.The first and second drive trains are separated from each other, in particular functionally and / or spatially, in such a way that the main drive motor cannot drive the consumers required for servicing the ground milling machine during maintenance operation. This eliminates the need to operate the main drive motor during maintenance operation. The described advantages also arise from the temporal separation of the operation of the main drive motor and the maintenance motor and the respective drive trains. One consumer required for servicing the milling drum during maintenance operation is, in particular, the compressor for providing compressed air, for example, for pneumatic tools.

[0012] As already mentioned, the main drive motor of a soil milling machine of this type is usually an internal combustion engine. The maintenance motor, on the other hand, can in principle be any type of engine. For example, it would be conceivable for the maintenance motor to be an electric motor, powered, for example, by a battery that is charged by the main drive motor during operation of the soil milling machine, or powered, for example, by an external power source. However, it is preferred that both the main drive motor and the maintenance motor be internal combustion engines, particularly diesel engines. Ideally, the main drive motor is significantly larger in power than the maintenance motor, in particular by a factor of greater than 10:1.Preferably, the two combustion engines are further arranged such that they are supplied with fuel from a common fuel tank via at least partially separate fuel lines. The main drive engine and the maintenance engine are thus both connected to the same fuel tank via at least partially separate fuel lines, from which they draw the same fuel, for example, diesel. By providing only one fuel tank for the main drive engine and the maintenance engine, the operation of the soil milling machine can be considerably simplified.

[0013] The compressor and any other consumers driven by the maintenance motor can be driven directly by the maintenance motor or, for example, via a suitable gearbox. In practice, however, it has proven particularly advantageous if the maintenance motor is not used directly to drive the compressor, but indirectly. The maintenance motor drives an energy converter as an intermediate energy stage, which in turn drives the compressor. The energy converter is characterized by the property that it converts one form of energy, for example mechanical energy, into another form of energy, for example hydraulic, pneumatic or electrical energy. It is preferred if the energy converter is designed in such a way that it converts mechanical energy from the maintenance motor into electrical or hydraulic energy to drive the compressor.According to the invention, a generator or a hydraulic pump, for example, can be used for this purpose. The maintenance motor thus drives, for example, a generator via its maintenance motor shaft, which generates electrical energy that is transmitted via electrical lines to the consumers, for example the compressor, and used to drive the consumers, for example the compressor. It is also possible for the maintenance motor to drive a hydraulic pump via its maintenance motor shaft, which thereby provides hydraulic energy in a hydraulic circuit in which this hydraulic energy is distributed via hydraulic lines to consumers, for example a hydraulic motor of the compressor, and used to drive the consumers, for example the compressor.

[0014] In principle, the second drive train can be designed such that the compressor is the only consumer driven by the maintenance motor. In this case, the maintenance motor drives exclusively the compressor. However, it is advantageous if the second drive train of the maintenance motor is designed and used to drive at least one further consumer in addition to the compressor. In particular, one or more of the following consumers are preferably considered for this purpose: a maintenance drive for slowly and gradually rotating the milling drum about its axis of rotation and / or a water pump for filling a water tank and / or for operating a cleaning device and / or a lifting drive for lifting the milling drum into a transport position and / or a roof drive for lowering or raising a roof, etc. Preferred consumers driven by the maintenance motor are explained in more detail below.

[0015] During maintenance operation of the soil milling machine, the milling drum is rotated slowly and gradually around its rotational axis to make all milling tools accessible to the operator for changing the milling tools. This can generally also be done manually, for example. However, it is preferred if this rotation of the milling drum during maintenance operation is driven by the maintenance motor. This can be achieved, for example, purely mechanically via a suitable gear system through which torque from the maintenance motor is transmitted to the milling drum. To drive the milling drum, the second drive train can, for example, be designed such that it drives a maintenance shaft specifically designed for maintenance operation of the milling drum, for example on the input side of a reduction gear.Alternatively, it is also possible for the maintenance motor to operate a maintenance drive via the energy converter, which in turn rotates the milling drum around its rotational axis. The maintenance drive can be an electric motor or a hydraulic motor, for example.

[0016] If the maintenance motor for driving the milling drum during maintenance operation partially uses gear sections that are also used by the main drive motor to drive the milling drum during work operation, there is a partial functional overlap between the first drive train and the second drive train. This functional area preferably represents the only area in which the first and second drive trains partially overlap functionally. Specifically, the maintenance motor can, for example, drive part of the first drive train via the second drive train on a reduction gear or similar arranged upstream of the milling drum, thereby causing the milling drum to rotate. However, even in this development of the invention, the first drive train and the second drive train are completely separate from one another except for the drive of the milling drum.The fundamental separation of the drive trains is therefore still present here, even if the second drive train is also capable of rotating the milling drum. In particular, the operation of the first and second drive trains, or rather the main drive motor and the maintenance motor, is temporally separated from one another according to the invention.

[0017] It has also proven advantageous if the maintenance motor drives a water pump in addition to the compressor, which can be used, for example, to fill a water tank on the soil milling machine. This water is sprayed into the milling drum housing during operation of the soil milling machine, for example, to cool the milling drum and / or to mix water into the milled material. The water pump can also be used during maintenance of the soil milling machine, for example, to operate a high-pressure cleaner with which cleaning work can be carried out on the soil milling machine.

[0018] A third type of operation, in addition to work mode and maintenance mode, is transport mode for the soil milling machine. During transport mode, the soil milling machine is moved from one location to another, for example between construction sites, between different locations within a construction site, etc. During transport mode, the milling drum must be raised off the ground. Usually, the milling drum housing is also raised off the ground to enable the soil milling machine to be transported without the milling drum housing or milling drum colliding with the ground or dragging against it. Particularly if the main drive motor of the soil milling machine is damaged during work mode and can no longer be operated, it is often problematic that the milling drum or milling drum housing can no longer be lifted off the ground.It is therefore difficult to tow such a defective soil milling machine from the construction site. Therefore, it is advantageous if the maintenance motor or the second drive train is designed in such a way that it is also capable of operating a lifting drive for raising the milling drum into a transport position. In other words, the maintenance motor or the second drive train is capable of moving both the milling drum and the milling drum housing from a lowered position into the ground, in which soil material is normally milled, into a transport position above the ground, disengaged from the soil material. With the milling drum housing and the milling drum in the transport position, it is then possible to tow the soil milling machine.The drive for the height adjustment of the milling drum, the soil milling machine itself and / or the milling drum box / milling drum hood can thus also represent a functional overlap area of ​​the first and the second drive train, wherein the second drive train is then preferably designed in such a way that the drive of the respective height adjustment takes place via the second drive train driven by the maintenance motor.

[0019] To further facilitate transport of the soil milling machine and to comply with legal regulations regarding the maximum machine height during transport, it is also advantageous if a roof drive for lowering or raising a roof can be operated by the maintenance motor. In particular, the roof drive is designed in such a way that it can ideally move the entire operator's platform of the soil milling machine vertically downwards or fold it to the side, forwards, or backwards, thus reducing the overall height of the machine. It is also possible for the roof drive to only move the roof of the operator's platform downwards or fold it to the side, thus also reducing the overall height of the machine.

[0020] The aforementioned additional consumers can generally be supplied with torque and operated directly by the maintenance motor via shafts. However, it is particularly advantageous if the at least one additional consumer is driven by the energy converter. The at least one additional consumer is thus supplied with energy either electrically or hydraulically by the energy converter and is thus only indirectly driven by the maintenance motor. Because no mechanical transmissions are required to operate the additional consumer, only electrical or hydraulic lines, these designs are particularly flexible and space-saving.

[0021] In general, it is possible for each described consumer of the second drive train, including the compressor, to be individually powered or operated either purely mechanically with torque from the maintenance motor or with electrical or hydraulic energy via the energy converter. It is also possible to drive almost any number of consumers with torque from the maintenance motor and simultaneously drive the other consumers via the energy converter. It would also be conceivable for all consumers that draw their energy from the maintenance motor to be operated exclusively through torque transmission from the maintenance motor.In contrast, however, it is preferred if the maintenance motor is designed such that it directly drives only the energy converter, and all consumers driven by the maintenance motor are connected to the energy converter in such a way that they are supplied with energy via it. Thus, only the energy converter is directly driven by the maintenance motor. All consumers that draw their energy from the maintenance motor, however, are supplied with the energy provided by the energy converter, particularly in the form of electrical and / or hydraulic energy. The electrical or hydraulic lines required for this are more space-saving and flexible than mechanical transmissions.

[0022] Like all devices driven by the maintenance motor, the milling drum can also be driven mechanically using the torque of the maintenance motor or indirectly via the energy converter during maintenance operation of the soil milling machine. However, it is preferred if the maintenance drive for rotating the milling drum is a hydraulic motor or an electric motor. In other words, the maintenance drive of the milling drum is powered by the energy converter using either electrical or hydraulic energy. This allows for particularly safe and easily controllable rotation of the milling drum during maintenance operation of the soil milling machine.

[0023] By separating the first and second drive trains in such a way that the consumers required exclusively during maintenance operation of the soil milling machine can be supplied with drive energy from the maintenance motor via the second drive train, it is possible to completely forgo operation of the main drive motor during maintenance operation of the soil milling machine. When the main drive motor is switched off, the risk of the milling drum being inadvertently operated at high power, which poses a danger to the operator during maintenance work on the milling drum, is eliminated. This design already provides a very high level of safety.To prevent the main drive motor from continuing to run or accidentally starting the soil milling machine during maintenance in the hustle and bustle of a construction site, it is preferable to have a safety circuit designed such that the maintenance motor and / or the compressor can only be operated when the main drive motor is switched off. The at least one safety circuit therefore ensures that the maintenance motor and / or the compressor can only be switched on when the main drive motor is not running or is switched off. If the maintenance motor cannot be started, all consumers required for maintenance operation that are powered by the maintenance motor are not operational. Maintenance operation cannot therefore be carried out at all while the main drive motor is running.If, however, only the compressor cannot be switched on as long as the main drive motor is not switched off, then the pneumatic tool for ejecting the milling tools from the tool holders cannot be used, making it impossible to change the milling tools directly on the milling drum. This prevents the operator from performing any work directly on the milling drum and is thus protected from the milling drum being accidentally started by the main drive motor. Preferably, the safety circuit is designed in such a way that other maintenance work, such as refilling the water tank via the water pump and / or moving a roof and / or driver's cab via a roof drive, is still possible. However, this work does not bring the operator into the immediate vicinity of the milling drum.For the specific implementation of the safety circuit, it is generally possible to use safety circuits known in the prior art. For example, the safety circuit can be an electronic safety circuit that prevents the maintenance motor and / or the compressor from starting when the main drive motor is running, and vice versa. For this purpose, the safety circuit can, for example, interrupt the motor power supply or something similar. The ultimate effect of the safety circuit is to prevent the main drive motor from starting while the maintenance motor and / or the compressor are running.

[0024] In soil milling machines of this type, a so-called pump distribution gearbox is often present. The pump distribution gearbox is usually driven on the input side by the main drive motor and has one or more connections for hydraulic pumps on the output side, which can be used to supply a hydraulic system with hydraulic energy. This hydraulic system often drives, for example, the ground milling machine's travel drive, which comprises hydraulic motors. To achieve the separation of the drive trains according to the invention, it is particularly advantageous if the pump distribution gearbox is designed such that it is driven exclusively by the first drive train. In other words, no drive energy is transferred from the second drive train to the pump distribution gearbox.This strict separation of the pump distribution gear from the second drive train prevents, purely structurally, any consumers connected to the second drive train from being supplied with drive energy via the pump distribution gear, and prevents consumers driven by the first drive train from being inadvertently driven by the maintenance motor. This ensures that the main drive motor cannot also drive consumers for maintenance operations. Furthermore, it also makes it possible to equip the maintenance motor with a relatively low power output.

[0025] The problem is also solved with a method for operating a ground milling machine, in particular a ground milling machine according to the above explanations. All features and their advantages described for the ground milling machine according to the invention can also be applied analogously to the method according to the invention, and vice versa.

[0026] Specifically, the method according to the invention for operating a ground milling machine in a working mode comprises driving a first drive train by a main drive motor and driving a milling drum by the first drive train. In a maintenance mode, it comprises driving a second drive train by a maintenance motor and driving a compressor by the second drive train. The main drive motor and the maintenance motor are operated independently of one another, and the compressor can be driven exclusively by the maintenance motor and not by the main drive motor. This is achieved by transmitting the drive energy from the maintenance motor to the compressor, spatially and functionally separated from the first drive train, exclusively via the second drive train.The main drive motor and the first drive train are therefore essentially dedicated to the working mode of the soil milling machine, while the maintenance motor and the second drive train are essentially dedicated to the maintenance mode of the soil milling machine. Maintenance mode of the soil milling machine is therefore possible without the operation of the main drive motor. The compressor can be operated without restrictions during maintenance mode without the main drive motor running. The main drive motor can be switched off during maintenance mode and therefore poses no danger to the operator due to the milling drum being accidentally engaged during maintenance mode.

[0027] A more flexible and space-saving design can be achieved if, during maintenance operation, mechanical energy is converted into hydraulic or electrical energy by an energy converter in the second drive train. This hydraulic or electrical energy, provided by the energy converter, is then used to drive the consumers. The energy converter converts the mechanical torque of the maintenance motor shaft into hydraulic energy via a hydraulic pump or into electrical energy via a generator, which is then used to drive the consumers.

[0028] To ensure maintenance operations are completely independent of the milling machine's operating mode, it is preferable for the milling drum to be rotated by the second drive train during maintenance operations to change milling tools. Apart from the milling drum, no other consumer of the milling machine is driven by both the first and second drive trains. Ideally, the second drive train drives the milling drum completely, bypassing the first drive train, for example, directly at the milling drum's milling tube.

[0029] It has proven advantageous if additional consumers can also be powered by the maintenance motor. This applies both during maintenance work on the soil milling machine and therefore when the main drive motor is switched off, and also in the event of a defect in the main drive motor that prevents the main drive motor from moving the soil milling machine, in particular the milling drum housing and the milling drum, into a transport position that allows transport of the soil milling machine, for example, by towing.It is therefore preferred that at least one additional consumer, particularly during emergency operation of the ground milling machine, be driven by the maintenance motor in addition to the compressor, in particular: driving a maintenance drive for rotating the milling drum about its rotational axis and / or driving a water pump and / or driving a lifting drive for lifting the milling drum into a transport position and / or driving a roof drive for lowering or raising a roof. Overall, any combination of the aforementioned consumers can generally be operated by the maintenance motor in addition to the compressor.

[0030] Since the safety of the operator is the top priority when operating the soil milling machine, it can also be provided that the operation of the main drive motor and the operation of the maintenance motor and / or the compressor are mutually exclusive. For this purpose, it is advantageous for a safety circuit to check whether the main drive motor is running, and for the second drive train to be driven by the maintenance motor and / or the compressor to be driven by the second drive train only when the main drive motor is out of operation. In other words, the compressor or the maintenance motor can only be switched on when the main drive motor is switched off. It is of course also possible for the safety circuit to work in the other direction and only allow the main drive motor to be switched on when the maintenance motor and / or the compressor are switched off.are not currently in operation. It is also conceivable that the safety circuit will switch off the main drive motor when the maintenance motor is switched on, if the main drive motor is still running when the maintenance motor is switched on, and vice versa. This reliably prevents an operator accident caused by the main drive motor accidentally driving the milling drum during maintenance of the soil milling machine.

[0031] The invention is explained in more detail below with reference to the exemplary embodiments illustrated in the figures. They show schematically: Fig. 1 a side view of a floor milling machine; Fig. 2 a first drive train of the soil milling machine; Fig. 3 a first embodiment of the second drive train of the soil milling machine; Fig. 4 a second embodiment of the second drive train of the soil milling machine; Fig. 5 a third embodiment of the second drive train of the soil milling machine; and Fig. 6 a flowchart of the method for operating the soil milling machine.

[0032] Identical elements are provided with the same reference numerals in all figures. Recurring elements are sometimes not identified separately in each figure.

[0033] In Fig. 1 shows a generic soil milling machine 1 in the form of a cold road milling machine of the center-rotor type, shown in side view, with a machine frame / chassis 3 and an operator's platform 2. During operation, the soil milling machine 1 mills soil material 7 in working direction a. The soil milling machine 1 travels on the undercarriages 6. The soil material 7 is milled by a milling drum 9, which is mounted in a milling drum housing 8 for rotation about a rotation axis 10. The milled material removed from the soil material 7 is transferred via the discharge device 5 in working direction a to a transport vehicle (not shown), where it is transported away.

[0034] Also in Fig. 1, a first drive train 11 is schematically shown, via which the main drive engine 4, here a diesel combustion engine, drives, among other things, the milling drum 9. The soil milling machine further comprises a second drive train 13, via which a maintenance engine 12, here also a diesel engine, drives a compressor 14. The first drive train 11 and the second drive train 13 are shown in the Fig. 1 are presented in a highly simplified manner and are used in conjunction with the Fig. 2 to 5 are explained in more detail below.

[0035] Fig. Figure 2 shows the basic structure of the first drive train 11 of the present embodiment. The main drive motor 4 is connected to the fuel tank 36 via a first fuel line 37 and is supplied with fuel, in this case diesel, from the fuel tank. The main drive motor 4 drives a pump distribution gear 16 via a first shaft 15. The pump distribution gear 16, in turn, drives a hydraulic system 18 via distribution shafts 17. The hydraulic system 18 consists of several hydraulic pump / motor units and performs various functions of the soil milling machine. For example, the undercarriages 6 and the discharge device 5 are supplied with power and operated by the hydraulic system 18. Via a second shaft 19, the main drive motor 4 drives a drive pulley 20, which forms a traction mechanism with a traction mechanism 21 and the driven pulley 22. The roller drive shaft 23 is driven by the main drive motor 4 via this traction mechanism.The roller drive shaft 23, in turn, drives the milling roller 9 for rotation about its rotation axis 10 via a reduction gear (not shown). The milling roller 9 is driven by the first drive train 11 of the main drive motor 4 during the working operation of the soil milling machine 1, in which soil material 7 is milled in the working direction a.

[0036] The Fig. 3 to 5 relate to alternative embodiments of the second drive train 13. As can be seen from the Fig. 2 with the Fig. 3, Fig. 4 and Fig. As can be seen in Figure 5, the maintenance motor 12, like the main drive motor 4, is also supplied with fuel from the fuel tank 36 via a second fuel line 38. The fuel tank 36 thus supplies the main drive motor 4 with fuel via the first fuel line 37 and the maintenance motor 12 via the second fuel line 38. The maintenance motor 12 drives a maintenance motor shaft 24, to which an energy converter 25 is connected. The energy converter is characterized in that it converts the mechanical energy introduced by the maintenance motor into another form of energy, in particular hydraulic or electrical energy. From the energy converter 25, which can in particular be either a generator or a hydraulic pump, the energy is distributed to consumers, such as the compressor 14, via lines 26 and switching elements 27.The part for transferring energy between the maintenance motor 12 and these consumers is referred to as the second drive train 13. The switching elements 27 enable the respective consumer to be switched on or off as required. In the case of a generator as the energy converter 25, these can be electrical switches, for example; in the case of a hydraulic pump as the energy converter 25, the switching elements 27 can be (hydraulic) valves, for example. The switching elements 27 therefore either allow energy to be transferred from the energy converter 25 to the respective consumer, or prevent this. In addition to the compressor 14, the energy converter 25 in the in . Fig. In the embodiment shown in Figure 3, a roof drive 28, a lifting drive 29, a water pump 30, and at least one further consumer 31 are also operated. All consumers driven by the maintenance motor 12 are thus supplied with electrical or hydraulic energy from the energy converter 25. Only the energy converter 25 is driven directly by the mechanical torque of the maintenance motor 12.

[0037] Fig. 4 shows a further embodiment of the second drive train 13. In contrast to the embodiment of Fig. 3, a maintenance shaft 32 is attached to the maintenance motor 12 next to the maintenance motor shaft 24, which can rotate the milling drum 9 about its rotational axis 10 via a coupling 33. This rotation of the milling drum 9, driven by the maintenance motor 12, occurs much more slowly than the rotation of the milling drum 9 during operation of the soil milling machine 1 by the main drive motor 4. In addition, the milling drum 9 is only rotated intermittently by a small angular section by the maintenance motor 12 so that an operator can reach other milling tools on the outer circumference of the milling drum 9. Furthermore, the drive energy applied by the maintenance motor 12 to rotate the milling drum 9 is so low that it is just sufficient to rotate the milling drum but cannot overcome larger resistance forces. The maintenance shaft 32 can be decoupled from the milling drum 9 via the coupling 33.Depending on the position of the clutch 33, the milling drum 9 is rotated or not by the maintenance motor 12. Different rotation speeds of the milling drum 9 during maintenance operation can also be set via the clutch 33, whereby the rotation speeds always remain within a safe range for the operator. The rotation of the milling drum 9 during maintenance operation of the soil milling machine 1 can be controlled by the operator via the clutch 33.

[0038] In the further embodiment of the second drive train 13 according to Fig. 5, the milling drum 9 can also be rotated by the maintenance motor 12 during maintenance operation of the soil milling machine 1 for maintenance purposes. However, the rotation of the milling drum 9 is not accomplished here by the direct transmission of torque from the maintenance motor 12 to the milling drum 9, but rather, as with the other consumers, occurs indirectly via the energy converter 25. Via a maintenance line 34, either electrical or hydraulic energy is transported from the energy converter 25 via a switching element 35, which can be either an electrical switch or a valve, to a maintenance drive 39. The maintenance drive 39 uses the electrical or hydraulic energy of the energy converter 25 to rotate the milling drum 9 slowly and in stages, as previously described, about its rotational axis 10 when the soil milling machine 1 is in maintenance operation. The maintenance drive 39 therefore comprises either an electric motor or a hydraulic motor.The rotation of the milling drum 9 can in the embodiment of the second drive train 13 of the . Fig. 5 can be controlled by the operator via the switching element 35, which either supplies the maintenance drive 39 with power or not. By controlling the amount of power supplied from the switching element 35 to the maintenance drive 39, the speed of rotation of the milling drum 9 during maintenance operation can also be continuously regulated, with the rotation speed always remaining within safe limits.

[0039] Both the first drive train 11 and the second drive train 13 are thus capable of causing the milling drum 9 to rotate about the rotation axis 10. A key aspect of the invention, however, is the separation of the drive trains. In the present case, this is to be understood as meaning that the first and second drive trains are structurally and functionally separate from one another in such a way that they do not drive any consumers together and simultaneously. The second drive train 13 is designed independently of both the first drive train 11 and the pump distribution gear 16. Furthermore, the operation of the drive trains 11, 13 is temporally separated.

[0040] From the Fig. 2 to 5 also show that a safety circuit 50, 51 is provided, each connected to the main drive motor 4 and the maintenance motor 12 and / or the compressor 14. The safety circuit 50, 51, which can also be designed as individual safety circuits separate from one another, prevents the main drive motor 4 from being operated simultaneously with the maintenance motor 12 and / or the compressor 14. For example, the safety circuit 50, 51 prevents the main drive motor 4 from being started as long as the maintenance motor 12 and / or the compressor 14 is switched on. Likewise, the safety circuit 50, 51 prevents the maintenance motor 12 and / or the compressor 14 from being operated as long as the main drive motor 4 is operating.Ultimately, the safety circuit 50, 51 ensures that only either the main drive motor 4 or the maintenance motor 12 and / or the compressor 14 can be operated at any one time. The safety circuit 50, 51 therefore prevents the main drive motor 4 from being operated simultaneously with the maintenance motor 12 and / or the compressor 14.

[0041] Overall, it is therefore possible to drive all components for maintenance operation of the soil milling machine 1, such as the compressor 14, the roof drive 28, the excavation drive 29, and the water pump 30, solely via the second drive train 13 by the maintenance motor 12. Operation of the main drive motor 4 is therefore not necessary during maintenance operation of the soil milling machine 1. On the contrary, this is even excluded by the safety circuit 50, 51. Because the high rotational speeds of the milling drum, as required during operation of the soil milling machine 1, can only be provided by the main drive motor 4, these high rotational speeds cannot be accidentally set during maintenance operation of the soil milling machine 1. The risk of accidents due to accidental and unintentional coupling of the milling drum 9 to the running main drive motor 4 is thus reliably avoided according to the invention.Personal injury to the operator as a result of such an event is excluded.

[0042] Fig. 6 shows a flowchart of the method 40 according to the invention for operating the soil milling machine 1. To clarify the separation of the first drive train 11 from the second drive train 13, the method steps that take place on the first drive train 11 and the second drive train 13 are each shown in separate dotted rectangles. The two drive trains 11, 13 thus represent separate functional compartments in which the various method steps take place. In the first drive train 11, during the working operation of the soil milling machine 1, the first drive train 11 is first driven 41. The first drive train 11 then drives 43 the milling drum 9 at high speed for the working operation of the soil milling machine 1, in which soil material 7 is milled. At the same time, the first drive train 11 also drives 45 the pump distributor gear 16.The pump distribution gear 16, in turn, drives the hydraulic system 18. Separate from the drive 41 of the first drive train 11, in particular separated in time, the second drive train 13 is driven 42 during maintenance operation of the soil milling machine 1. The driven second drive train 13 drives 44 of the compressor 14, 46 of the roof drive 28, 47 of the excavation drive 29, and 48 of the water pump 30. The only point of contact or the only intersection of the first drive train 11 with the second drive train 13 is shown in FIG. Fig. 1 by the dashed arrow, which represents the driving 43 of the milling drum 9 by the second drive train 13 driven in step 42. As can be seen from the Fig.As can be seen in Figure 6, the first drive train 11 and the second drive train 13 are strictly separated from each other, except for this overlap when driving the milling drum 9. This separation makes it possible to carry out maintenance operations on the ground milling machine 1 entirely without the aid of the main drive motor 4. This motor can be switched off during the entire maintenance work during maintenance operations on the ground milling machine 1. This prevents the operator from being endangered by accidentally starting the milling drum 9 by engaging the main drive motor 4 when changing the milling tool on the milling drum 9.

Claims

[1] Soil milling machine (1) for milling soil material (7), comprising - a main drive motor (4), - a first drive train (11) driven by the main drive motor (4), and - a milling drum (9) driven by the main drive motor (4) via the first drive train (11) and rotatably mounted in a milling drum housing (8) for milling soil material (7) during the operation of the soil milling machine (1), characterized by, that a maintenance motor (12) is provided which drives a compressor (14) to provide compressed air via a second drive train (13) separately from the main drive motor, wherein the compressor (14) can be driven exclusively by the maintenance motor (12) via the second drive train (13), and wherein the maintenance motor (12) drives an energy converter (25) which in turn drives the compressor (14), and that the energy converter (25) provides either electrical or hydraulic energy to drive the compressor (14). [2] Soil milling machine (1) according to claim 1, characterized by , that both the main drive engine (4) and the maintenance engine (12) are internal combustion engines, in particular diesel engines, and are supplied with fuel from a common fuel tank (36) via at least partially separate fuel lines (37, 38). [3] Soil milling machine (1) according to one of the preceding claims, characterized by, that the maintenance motor (12) is connected to at least one additional consumer in addition to the compressor (14) and supplies it with energy, in particular at least one of the following consumers: - a maintenance drive (39) for rotating the milling drum (9) about its axis of rotation (10) and / or - a water pump (30) and / or - a lifting drive (29) for lifting the milling drum (9) into a transport position and / or - a roof drive (28) for lowering or raising a roof. [4] Soil milling machine (1) according to claim 3, characterized by , that at least one other consumer is powered by the energy converter (25). [5] Soil milling machine (1) according to claim 3, characterized by, that the maintenance motor (12) is designed in such a way that it exclusively drives the energy converter (25) directly and all consumers driven by the maintenance motor (12) are connected to the energy converter (25) in such a way that they are supplied with energy via it. [6] Soil milling machine (1) according to any one of claims 3 to 5, characterized by , that the maintenance drive (39) for rotating the milling drum (9) is a hydraulic motor or an electric motor. [7] Soil milling machine (1) according to one of the preceding claims, characterized by , that a safety circuit (50, 51) is provided which is designed such that the maintenance motor (12) and / or the compressor (14) can only be operated when the main drive motor (4) is switched off. [8] Soil milling machine (1) according to one of the preceding claims, characterized by , that a pump distribution gearbox (16) is present, which is driven exclusively by the first drive train (11). [9] Method (40) for operating a soil milling machine (1) according to one of the preceding claims, in a working operation comprising - the driving (41) of a first drive train (11) by a main drive motor (4) and - the driving (43) of a milling drum (9) by the first drive train (11), and in a maintenance operation comprising - the driving (42) of a second drive train (13) by a maintenance motor (12) and - the driving (44) of a compressor (14) by the second drive train (13), wherein the main drive motor (4) and the maintenance motor (12) are operated independently of each other, and wherein the maintenance motor (12) drives an energy converter (25) which in turn drives the compressor (14), and that the energy converter (25) provides either electrical or hydraulic energy to drive the compressor (14). [10] Method (40) according to claim 9, characterized by, that during maintenance operation in the second drive train (13) a conversion of mechanical energy into hydraulic or electrical energy takes place by an energy converter (25). [11] Method (40) according to any one of claims 9 to 10, characterized by , that during maintenance operation, the milling drum (9) is rotated by the second drive train (13) to change milling tools. [12] Method (40) according to any one of claims 9 to 11, characterized by , that at least one additional consumer besides the compressor (14) is driven by the maintenance motor (12), in particular: - driving a maintenance drive (39) to rotate the milling drum (9) about its axis of rotation (10) and / or - driving a water pump (30) and / or - driving a lifting drive (29) to lift the milling drum (9) into a transport position and / or - a drive for a roof drive (28) to lower or raise a roof. [13] Method (40) according to any one of claims 9 to 12, characterized by , - that a safety circuit (50, 51) checks whether the main drive motor (4) is in operation, and - that the driving (42) of the second drive train (13) by the maintenance motor (12) and / or the driving (44) of the compressor (14) by the second drive train (13) only takes place when the main drive motor (4) is out of service.

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