EP4071301B1 - Self-propelled ground milling machine and method for operating a ground milling machine in emergency operation - Google Patents

Description

The invention relates to a ground milling machine and a method for operating a ground milling machine in an emergency mode.

A generic ground milling machine is self-propelled and includes a machine frame, a control stand, a primary drive unit with which the drive energy required for the regular operation of the ground milling machine is made available, a ground milling device with a milling drum arranged inside a milling drum box and rotatable about an axis of rotation, and front and rear milling drums Driving devices, wherein at least one of the front and/or the rear driving devices is connected to the machine frame via a vertically adjustable lifting device. Such ground milling machines are, for example, from DE102015016678A1 and the DE102014019168A1 known. The DE102014011195A1 describes such a ground milling machine in which a maintenance motor separate from the main drive motor can operate a compressor for maintenance work, for example. Such ground milling machines are usually used in road and path construction, for example for roadway rehabilitation. To do this, the ground milling machines can lower the milling drum into the subsoil and remove layers of soil to a desired milling depth. Even if these machines are basically reliable in use, operating situations can arise in which the prime mover stops working, for example due to engine damage. Since ground milling machines are often used in construction site situations that are subject to high deadline pressure, it is important in such cases to be able to move the ground milling machine out of the specific construction site position as quickly as possible so that, for example, milling work can be continued by another ground milling machine. Ground milling machines, in particular of the mid-rotor type, in which the ground milling device is arranged between the front and rear driving devices, such as wheels and/or crawler tracks, as seen in the direction of travel of the machine, are very heavy machines and cannot usually be removed without increased effort if the primary drive unit is defective offset. The DE102012022732A1 suggests as a possible solution that the ground milling machine be converted into a towable vehicle with the help of an auxiliary drive state can be brought. While this approach is helpful, towing rotary tillers is also time-consuming and often requires dedicated towing vehicles.

Proceeding from this, the object of the invention is to provide a way of being able to better move and relocate a ground milling machine when the primary drive unit is defective.

The task is solved with a ground milling machine and a method according to the independent claims. Preferred developments are specified in the dependent claims.

A generic self-propelled ground milling machine thus comprises a machine frame which forms the essential support structure of the ground milling machine. There is also a control station from which the floor milling machine is operated during transport and milling operations. The drive energy required for regular operation of the ground milling machine is generated by a primary drive assembly of the ground milling machine. This can in particular be a diesel internal combustion engine. Part of the ground milling machine is also a ground milling device with a milling drum arranged inside a milling drum box and rotatable about an axis of rotation. Finally, there are front and rear travel devices, wherein at least one of the front and/or the rear travel devices can preferably be connected to the machine frame via a lifting device that can be adjusted in the vertical direction. In particular, it can also be provided that all of the travel devices are each connected to the machine frame via a lifting device.

Driven units are often driven hydraulically. For a ground milling machine of this type, it is provided in this connection that there is at least one hydraulic drive circuit for driving at least one of the travel devices and/or for driving a milled material conveying device. The drive circuit comprises at least one main hydraulic pump driven by the prime mover and at least one hydraulic motor driven by the main hydraulic pump in a closed hydraulic circuit. The at least one hydraulic motor is thus in particular a travel drive hydraulic motor or a conveyor belt drive motor. In such a closed hydraulic circuit, the main hydraulic pump is thus fed in a closed circulation system with the hydraulic fluid returning from the respective hydraulic motor. In such a closed hydraulic circuit, pressurized hydraulic fluid is therefore present in the line system both on the high-pressure side and on the low-pressure side. A closed hydraulic circuit of the present type can also have other elements that consume torque and/or hydraulic fluid volume, such as a feed pump to compensate for leakage oil losses, a flushing branch, etc. Several hydraulic motors, in particular connected in parallel, can also be driven by a closed hydraulic circuit. In ground milling machines of the generic type, this can be the case, for example, with the traction motors of the traction devices.

According to the invention, it is now provided that the at least one hydraulic drive circuit in the conveying direction has a disconnection and/or connection point in front of and behind the at least one hydraulic motor, in particular in each case. A separation and/or connection point thus designates a device within the hydraulic fluid routing of the closed hydraulic circuit, with which the closed hydraulic circuit can be separated with regard to its hydraulic fluid routing (separation point). A hydraulic emergency supply system can now be connected at this point of separation or at another point, as described below. The separation and/or connection point is thus a device that is already set up in such a way that it is designed for, at least functionally, separating the existing hydraulic lines and for connecting other hydraulic lines. This can also include a physical disconnection of one or more lines of the closed hydraulic circuit and/or a purely functional disconnection, for example via one or more, in particular pre-installed, valves. Combinations are also possible. The design as a separation and/or connection point expresses the fact that another hydraulic fluid connection can be connected at the separation point to the hydraulic motor. The closed hydraulic circuit thus includes set separation and/or access points for connecting an emergency hydraulic pump. The emergency hydraulic pump is part of a hydraulic emergency supply system, ideally permanently installed in the ground milling machine. The emergency supply system can be connected to the disconnection and connection points for emergency operation of the at least one hydraulic motor in such a way that the closed hydraulic circuit is interrupted and hydraulic fluid can be conveyed from the emergency hydraulic pump in an open emergency hydraulic circuit to drive the at least one hydraulic motor, bypassing the main hydraulic pump. This makes it possible to drive the hydraulic pump at least for a limited period of time with little power, but sufficiently to empty the belt and/or to drive the ground milling machine. The essential step here is, on the one hand, to open the closed hydraulic circuit, which is intended for regular operation, so to speak, and thus make it accessible for operation by the emergency hydraulic pump. On the other hand, bypassing the main hydraulic pump, which does not have to be towed, increases the efficiency of this emergency system. Practically the entire hydraulic power of the emergency hydraulic pump is available to drive the hydraulic motor, which was previously integrated in the closed hydraulic circuit. In this way, the emergency hydraulic pump can be designed to be small and compact and comparatively inefficient compared to the main hydraulic pump, for example.

It can be provided that the drive of the conveyor belt and the travel drive take place via mutually separate, closed hydraulic circuits, each comprising a main hydraulic pump and at least one hydraulic motor. In this case it can be provided that both of the closed hydraulic circuits each have separation and connection points of the type described above. However, in this case, in particular, only a single emergency hydraulic pump can be provided on the ground milling machine, so that usually a connection is made successively at first to the closed hydraulic circuit of the conveyor belt for emptying the conveyor belt load and then changing the connection of the emergency hydraulic pump to the closed hydraulic circuit of the travel drive for moving the ground milling machine. This can be done manually, for example, by reconnecting hoses and/or using suitable valves.

With regard to the specific positioning of the separation and connection points in the closed hydraulic circuit, there are various possible variations. In principle, it is advantageous if the separation and connection points are positioned in the conveying direction of the closed hydraulic circuit in such a way that conveying distances are as short as possible. Irrespective of this, it is advantageous if, when the emergency supply system is connected, a feed pump and/or a rinsing stage of the closed hydraulic circuit are bypassed by the open emergency hydraulic circuit. It is ideal if, when connecting the emergency supply system, in particular all elements of the closed hydraulic circuit that consume torque and/or hydraulic fluid, apart from the respective at least one hydraulic motor, are bypassed. In this way it is ensured that the largest possible proportion of the hydraulic energy generated by the emergency hydraulic pump can be used to drive the respective hydraulic motor. It is preferred if the separation and/or connection point can be reached and/or operated from the operator's station.

Various preferred developments of the separation and connection points are also covered by the invention in terms of construction. In particular, the separation and connection points can have switching valves, especially 3/2 or 4/3-way valves, especially comprising a blocking position and one or two delivery positions. Such switching valves can also be supplemented with couplings, in particular quick couplings, in order to facilitate the disconnection of the closed hydraulic circuit and the connection of the emergency hydraulic pump and a tank discharge line. In addition or as an alternative, it can be provided that the line system of the emergency supply system is fully or partially pre-installed on the ground milling machine, for example in the form of pre-installed piping and/or hoses, and/or is produced in an emergency, for example by using flexible hoses etc. The same way Suitable switching means, for example for use as a disconnection and/or connection point, can also be pre-installed or only produced when required.

The main task of the emergency hydraulic circuit is to provide at least sufficient drive energy in an emergency to enable powered belt emptying and/or at least slow drive of the ground milling machine so that it can move to another location and/or onto a transport vehicle under its own power can move. For this purpose, the emergency hydraulic circuit can have a hydraulic pump, in particular a controllable one, as an emergency hydraulic pump. This can be permanently installed on the floor milling machine. In order to be able to control, for example, a forward and/or reverse movement and/or a blocking position, a switching valve, which can be operated in particular by hand, especially a 4/3-way valve. For practical operation, it has proven useful if there is a control element of the emergency hydraulic circuit that is arranged or can be arranged in the control stand of the ground milling machine.

The drive energy required to drive the emergency hydraulic pump can be provided by the primary drive unit or by an auxiliary drive unit that is independent of the primary drive unit. The auxiliary drive unit can have an internal combustion engine and/or an electric motor, for example. The auxiliary drive unit is preferably arranged in the engine compartment of the ground milling machine. The emergency hydraulic pump may be a separate dedicated emergency hydraulic pump. However, provision can also be made for an existing hydraulic pump, which is operated in an open hydraulic circuit during regular operation of the ground milling machine, to be turned into an emergency hydraulic pump in an emergency by suitably changing the connection paths, in particular as described above and below.

The extent to which components of the emergency supply system are pre-installed in the ground milling machine can vary. In the extreme case, it can be provided that the conversion to drive the at least one hydraulic motor by the emergency supply system is carried out entirely by hand. On the other hand, it is also possible for the entire emergency supply system to be permanently installed in the ground milling machine. It is also conceivable that a machine control system automatically recognizes the emergency supply operation or that such a mode is specified manually by an operator. Operating elements can be used to control the emergency supply system, which are used in normal operation for the normal operation of the ground milling machine. This has the advantage that no additional controls have to be installed. However, separate controls are possible. One or more safety circuits can also be provided, for example to protect one or more hydraulic pumps, etc. It has proven useful if the ground milling machine has at least partially permanently installed pipelines and/or hydraulic hoses of the emergency supply system, in order to ensure reliable and, in particular, easier conversion in an emergency make possible. To lead to the separation and connection points, it is advantageous if the emergency supply system has flexible hose pieces, in particular comprehensively connecting elements that can be connected to the separation and connection points. Conversely, it is also preferable if the emergency supply system does not have a structurally fixed connection to the closed hydraulic circuit in regular operation. This serves in particular to ensure operational safety, for example in order to prevent an unwanted connection to a fluid-conducting connection from components of the emergency supply system to the closed hydraulic circuit which is under comparatively high pressure.

It is advantageous if the emergency hydraulic pump is driven completely independently of the primary drive assembly, in particular by means of at least one opposite the primary drive assembly by a factor of 5, in particular at least by a factor of 10, less powerful auxiliary drive unit.

It is known that ground milling machines have an auxiliary motor, for example in order to be able to rotate a milling drum independently of a significantly more powerful primary drive unit during maintenance work. Such an auxiliary engine for generating drive energy independently of the primary drive unit can now also be used according to the invention additionally or alternatively to generate compressed air for a chisel hammer, to drive a pump for filling the water tank of the ground milling machine or to fulfill other drive functions. It is ideal if this auxiliary motor is also designed to drive the emergency hydraulic pump at the same time and thus fulfills at least a double function. It is then possible to operate the emergency supply system without the drive energy required for this having to be generated by the primary drive unit.

The separation and/or connection point is preferably selected in such a way that a reversal of the conveying direction and thus reverse operation of the at least one hydraulic motor by the emergency supply system is also possible.

It is possible that, in addition to driving the milled material conveying device and/or one or more driving devices, other functionalities can also be integrated into the present drive concept for emergency operation of a ground milling machine. This can be, for example, the drive of steering devices, pivoting devices, roof adjustments, etc. In principle, all hydraulic motors can be taken into account here in a corresponding manner.

The ground milling machine is particularly preferably suitable for carrying out the method according to the invention described below.

A further aspect of the invention relates to a method for operating a ground milling machine, in particular a ground milling machine according to one of the preceding claims, in an emergency mode. Essential steps are the disconnection of a closed hydraulic circuit with a main hydraulic pump and a hydraulic motor provided in regular operation for driving at least one driving device and/or at least one milled material conveyor at at least one disconnection and connection point, that, in particular, subsequent establishment of a connection via the at least one disconnection and connection point to an emergency hydraulic pump, and finally the delivery of hydraulic fluid by the emergency hydraulic pump to the hydraulic motor, bypassing at least the main hydraulic pump, in particular bypassing all other elements of the (former) closed hydraulic circuit that consume torque and/or hydraulic fluid. Since there is no longer a closed hydraulic circuit system in emergency operation, it is also advantageous that the other of the two separation and connection points, a discharge line is established to a hydraulic tank. In this way, the fluid conveyed by the emergency hydraulic pump to the hydraulic motor can be returned to the hydraulic tank essentially without pressure. More than one separation and/or connection point can also be provided, in particular at least two.

Basically, it is preferred if an already existing tank system used for regular operation is used for this purpose, both with regard to the hydraulic fluid supply of the emergency hydraulic pump and with regard to the return line of the hydraulic fluid from the hydraulic motor to the tank.

The emergency hydraulic pump is preferably driven by an auxiliary drive unit that can be operated completely independently of the primary drive unit. Even in the event of a total failure of the primary drive assembly, emergency operation is still possible in this way, which, for example, at least enables slow driving and/or slow unloading of the conveying device.

Fig. 1

eine Seitenansicht auf eine Bodenfräsmaschine vom Mittelrotortyp;

Fig. 2

eine Draufsicht auf die Bodenfräsmaschine aus Figur 1;

Fig. 3

ein Hydraulikschaltplan; und

Fig. 4

ein Ablaufdiagramm eines erfindungsgemäßen Verfahrens.

The invention is explained in more detail below with reference to the exemplary embodiments illustrated in the figures. They show schematically:

1

a side view of a center rotor type rotary tiller;

2

a top view of the floor milling machine figure 1 ;

3

a hydraulic circuit diagram; and

4

a flowchart of a method according to the invention.

Identical components are denoted by the same reference symbols in the figures, although not every component that is repeated in the figures is necessarily marked with a reference symbol in each figure.

figure 1 shows a ground milling machine 1 in a side view, specifically on the right side of the machine in relation to the forward direction A. The essential elements of the ground milling machine 1 are a machine frame 2, a primary drive unit 3, preferably a diesel internal combustion engine, a ground milling device 4, front driving devices 5, rear driving devices 6 and a control station 7. The soil milling device comprises a milling drum box 8, inside which a (in figure 1 dashed line indicated) milling drum 9 is present. This can comprise a hollow-cylindrical supporting tube, on the outer surface of which a multiplicity of milling tools are arranged. The milling drum 9 is rotatable about a horizontal axis of rotation R running transversely to the forward direction A. In the milling operation, the milling drum 9 engages in the subsoil U and thereby mills up subsoil material. The resulting milled material is collected in the milling drum box 8 and can then be loaded via transport devices 10 and 11, for example onto a transport vehicle. The transport device 10 can be an internal conveyor belt, whereas the transport device 11 can be a so-called external or trailer conveyor belt. The exemplary embodiment shown in the figures shows a ground milling machine 1 in which the ground milling device 4 is arranged between the front driving devices 5 and the rear driving devices 6 as seen in the forward direction A. However, the invention also extends to such ground milling machines in which the ground milling device 4 is arranged at the level of the rear driving devices 6 seen in the forward direction A, as is the case with so-called tail rotor milling machines. These ground milling machines are used, for example, for milling asphalt or for milling open asphalt surfaces in need of rehabilitation. In the milling operation, the ground milling machine 1 usually moves in the forward direction A, so that this direction can also be referred to as the working direction. The ground milling machine is thus in particular a road cold milling machine.

The driving devices 5 and/or 6 can be connected to the machine frame 2 via lifting devices, for example lifting columns 12 in the present case. By adjusting the height of the lifting columns 12, the vertical spacing of the machine frame and thus, for example, the immersion depth of the milling drum 9 in the subsoil U can be varied. In the present case, all of the front and rear driving devices 5/6 are each connected to the machine frame 2 via such a lifting column 12 . Embodiments are also conceivable in which only the front or only the rear driving devices are connected to the machine frame via corresponding lifting columns.

The drive energy required to operate the ground milling machine 1 is provided by the primary drive unit 3 . This can be arranged in the rear of the machine, such as in the figure 1 shown. There is also a hydraulic drive system. Individual hydraulic consumers of the ground milling machine 1 can be arranged in one or more closed hydraulic circuits. Hydraulic consumers of this type can be hydraulic motors, for example hydraulic motors 13 for driving and/or hydraulic motors 14 for driving the transport devices 10 and 11. An example of the hydraulic motor 13 for driving the driving devices 6 on the right-hand side behind the ground milling machine 1 is shown in figure 1 a main hydraulic pump 15 driven directly or indirectly by the primary drive unit 3 is provided, which is located in an in figure 1 only indicated closed hydraulic circuit 16 is arranged with the hydraulic motor 13. The same can be the case for the remaining hydraulic motors 13 and/or 14 . Several closed hydraulic circuits can also be provided, for example a closed hydraulic circuit for two or more hydraulic motors 13 of the driving devices 5 or 6, and another separate closed hydraulic circuit for driving the hydraulic motor or motors 14. Each closed hydraulic circuit preferably has its own main hydraulic pump 15 on.

figure 3 illustrates further details on the closed hydraulic circuit 16 and the auxiliary connection of an emergency hydraulic pump 17 according to the invention Hydraulic circuit 16 are the main hydraulic pump 15 and the hydraulic motors 13 connected via the line system in a closed hydraulic circuit figure 3 Furthermore, the hydraulic motor 13′ gives the option that several hydraulic motors, preferably connected in parallel to one another, can be connected in a common, closed hydraulic circuit 16. In the present case, this can be the case in particular for the hydraulic motors of the driving devices 5 and 6 . The closed hydraulic circuit 16 according to figure 3 also includes a feed pump 18, which is designed to compensate for, for example, leakage oil losses and/or for cooling and/or filtering purposes branched off amounts of fluid from the closed hydraulic circuit. This can be structurally combined in a pump module 19 . A rinsing device can also be provided, which can also be designed as a modular building block 20 .

In the closed hydraulic circuit 16, in the present case in particular outside of the two modules 19 and 20 in the line system of the hydraulic circuit 16, two separation and connection points 21A and 21B are provided. The line system of the closed hydraulic circuit 16 can be opened and connected to the emergency hydraulic pump 17 via the separation and connection points 21A and 21B. The emergency hydraulic pump 17 or the corresponding emergency supply system comprises two connection points 22A and 22B in order to preferably enable a fluid-conducting connection in both directions of flow of the hydraulic motor 13 . In the present case, this allows the ground milling machine 1 to drive forwards and backwards under its own power, even during emergency operation, which can make maneuvering easier.

figure 3 clarifies that the separation and connection points 21A and a 21B are arranged in the closed hydraulic circuit 16 in such a way that the main hydraulic pump 15, the feed pump 18 and the rinsing stage 20 are not supplied with hydraulic fluid when the emergency hydraulic pump 17 is connected and accordingly by the connection of the Emergency hydraulic pump 17 obtained open hydraulic circuit to the hydraulic motor 13 are bypassed.

The emergency hydraulic circuit obtained can have a valve device 23 which is arranged between the emergency hydraulic pump and the hydraulic motor 13 and can be actuated manually, in particular via an actuating lever 24 . The connection to a control unit of the floor milling machine is also possible here. The conveying direction towards the hydraulic motor 13 can be reversed with the aid of the valve device 23 . A blocking position of the valve device 23, which prevents any fluid delivery in the open hydraulic circuit, can be provided.

The emergency hydraulic pump 17 can be driven by an electric motor, an auxiliary motor and/or by the prime mover.

figure 4 finally illustrates the sequence of a method according to the invention for operating a ground milling machine 1 in an emergency mode. In step 25, after the primary drive unit has failed, for example, a closed hydraulic circuit with a main hydraulic pump and a hydraulic motor, which is provided in regular operation to drive at least one traction device and/or at least one milled material conveyor, is first separated at two separation and connection points, for example as in figure 3 shown. It is then provided that in step 26 a connection is established via at least one of the two separation and connection points to an emergency hydraulic pump. If this has happened, in step 27 hydraulic fluid can be conveyed by the emergency hydraulic pump to the hydraulic motor, bypassing at least the main hydraulic pump, in particular bypassing all elements consuming torque and/or hydraulic fluid.

Claims (9)

1. A self-propelled ground milling machine (1), comprising

   - a machine frame (2), an operator platform (7), a primary drive unit (3), a ground milling device (4) with a milling drum (9) arranged within a milling drum box (8) and rotatable about a rotation axis (R), front (5) and rear (6) travel units, wherein at least one of the front and/or rear travel units (5, 6) is connected to the machine frame (2) via a vertically adjustable lifting device;

   - wherein at least one hydraulic drive circuit is provided for driving at least one of the travel units (5, 6) and/or for driving a milled material conveyor, with at least one main hydraulic pump (15) driven by the primary drive unit (3) and at least one hydraulic motor (13, 13') driven by the main hydraulic pump (15) in a closed hydraulic circuit,;
   characterized in that

   - the at least one hydraulic drive circuit has a separation and/or connection point (21A, 21B) upstream and downstream of the at least one hydraulic motor (13, 13'); and

   - the ground milling machine (1) has an emergency hydraulic pump (17) which is part of a hydraulic emergency supply system;

   wherein the emergency supply system can be connected to the separation and/or connection point (21A, 21B) for emergency operation of the hydraulic motor (13, 13') such that hydraulic fluid can be conveyed by the emergency hydraulic pump (17) in an open emergency hydraulic circuit to drive the at least one hydraulic motor (13, 13') while bypassing the main hydraulic pump (15).
2. The self-propelled ground milling machine (1) according to claim 1,
   characterized in that
   the separation and connection points (21A, 21B) in the closed hydraulic circuit (16) are positioned such that

   - when connecting the emergency supply system, a feed pump (18) and/or a purge stage (20) of the closed hydraulic circuit (16) are bypassed by the open emergency hydraulic circuit;

   - when connecting the emergency supply system, in particular, all torque- and/or hydraulic fluid-consuming elements of the closed hydraulic circuit (16) are bypassed except for the at least one hydraulic motor (13, 13').
3. The self-propelled ground milling machine (1) according to any one of the preceding claims, characterized in that
   the separation and connection points (21A, 21B) include at least one of the following features:

   - they comprise switching valves, especially 3/2- or 4/3-way valves, in particular comprising a blocking position and one or two conveying positions;

   - they comprise quick couplings.
4. The self-propelled ground milling machine (1) according to any one of the preceding claims, characterized in that
   the emergency hydraulic circuit includes at least one of the following features:

   - it comprises a hydraulic pump, in particular a controllable hydraulic pump;

   - it comprises a hydraulic pump permanently installed on the ground milling machine (1);

   - it comprises a switching valve, in particular one that can be operated manually;

   - it comprises in particular a 4/3-way valve;

   - it comprises a control element arranged or arrangeable on the operator platform (7) of the ground milling machine (1).
5. The self-propelled ground milling machine (1) according to any one of the preceding claims, characterized in that
   the emergency supply system includes at least one of the following features:

   - it comprises pipelines and/or hydraulic hoses permanently installed in the ground milling machine (1);

   - it comprises flexible hose sections for approaching the separation and connection points (21A, 21B), in particular comprising connecting elements that can be connected to the separation and connection points (21A, 21B).
6. The self-propelled ground milling machine (1) according to any one of the preceding claims, characterized in that
   the emergency hydraulic pump (17) is driven completely independently of the primary drive unit (3), in particular by means of an auxiliary drive unit which is by at least a factor of 5, in particular by at least a factor of 10, less powerful than the primary drive unit (3).
7. A method for operating a ground milling machine (1), according to any one of the preceding claims, in an emergency mode of operation, comprising the steps of:

   - separating, at at least one separation and/or connection point (21A, 21B)., a closed hydraulic circuit (16) having a main hydraulic pump (15) and a hydraulic motor (13, 13') and provided in regular operation for driving at least one travel unit (5,6) and/or at least one milled material conveyor;

   - establishing a connection to an emergency hydraulic pump via at least one of the two separation and connection points (21A, 21B);

   - conveying, by the emergency hydraulic pump (17), hydraulic fluid to the hydraulic motor (13. 13') while bypassing at least the main hydraulic pump (15), in particular while bypassing all torque- and/or hydraulic fluid-consuming elements.
8. The method according to claim 7,
   characterized in that
   the method further includes establishing a discharge line to a hydraulic tank.
9. The method according to any one of claims 7 or 8, characterized in that
   the emergency hydraulic pump (17) is driven by an auxiliary drive unit that can be operated completely independently of the primary drive unit (3).

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