Valve arrangement for mobile working machines comprising a hydraulic consumer

Abstract

The invention relates to a valve arrangement for a mobile working machine (1), said valve arrangement comprising: a hydraulic consumer (47, 50); at least one directional control valve (30, 31, 55, 64) which is connected to a pressure line (P1, P2, 56, 65) and a working line (A1, A2, 52, 54) of the hydraulic consumer (47, 50) and which comprises a hydraulic control line (C, 58, 63) which is designed to transfer the at least one directional control valve (30, 31, 55, 64) to a first position; a pilot valve (32, 59) which is connected to the hydraulic control line (C, 58, 63); a pressure supply line (Pa, 66); and a pressure relief line (T, 62), the pilot valve (32, 59) being designed to connect the hydraulic control line (C, 58, 63) alternately to the pressure supply line (Pa, 66) and to the pressure relief line (T, 62).

Description

[0001] Valve arrangement for mobile work machines with hydraulic consumers

[0002] The present invention relates to a valve arrangement, a use of such a valve arrangement, a mobile work machine having the features of the preamble of claim 15 and a method for minimizing hydraulic oil loss in a mobile work machine.

[0003] Mobile work machines with hydraulic systems, especially mobile hydraulic construction machines, are widely used on construction sites for demolition and demolition work. Such mobile work machines are also used in civil engineering and forestry. Examples of mobile work machines include cranes, excavators, material handlers, forestry machines, and the like. Long-arm boom excavators, or demolition excavators, are used in demolition. The long booms and sticks make mobile hydraulic construction machines a good tool for using hydraulic attachments for the respective purpose, even at heights of over 20 m. During operation of mobile hydraulic construction machines, the hydraulic hoses that make up the hydraulic system of the attachments are exposed to external influences due to aging processes or weathering, which can cause damage to the hydraulic hoses.Further, and much more unpredictable, sources of damage include external mechanical impacts on hydraulic hoses caused by work in confined spaces. The excavator operator cannot see every part of the boom of the mobile hydraulic construction machine during operation, so hydraulic hoses can get caught on sharp objects on the construction site, punctured, torn off, cut open, and crushed, resulting in damage. Due to unavoidable aging processes and unpredictable external influences, oil leaks can occur in hydraulic hoses during normal operation of the construction machine.It is known, among other things, from the published patent application EP 25 47 912 to interrupt lines in the hydraulic system on the attachment that have been damaged by pipe bursts, so that the attachment does not make any uncontrolled movements, remains in a rigid position and does not pose a safety risk on the construction site. However, this only interrupts the hydraulic system on the side of the attachment, which is critical because the long booms and sticks of mobile hydraulic construction machines also require long hydraulic lines that have to be led to the end of the stick to the attachment. This means that in the event of an oil leak, more than 400 liters of oil can escape in less than half a minute and reach the bottom of the construction site. The loss of the often very hot oil not only means additional costs for replacing the lost oil, but also considerable environmental pollution of the construction site and often poses a considerable risk to people.

[0004] The same applies to the use of harvesters in forestry, some of which have tongs for gripping tree trunks on long booms or boom assemblies, which, in addition to the hydraulic unit for the tongs, are also equipped with a hydraulic motor for rotating the tongs.

[0005] The invention is therefore based on the object of providing a reliable, relatively simply constructed valve arrangement and an environmentally friendly hydraulic working machine as well as a method for minimizing hydraulic oil loss in a mobile working machine in the event of a leak in a working line and a corresponding use of a valve arrangement.

[0006] This object is achieved by a valve arrangement having the features of claim 1 and a use having the features of claim 14, by a work machine having the features of claim 15 and by a method for minimizing hydraulic oil loss in a mobile work machine having the features of claim 18. Accordingly, a valve arrangement for a mobile work machine with a hydraulic consumer is provided,

[0007] - with at least one directional control valve which is connected to a pressure line and a working line of the hydraulic consumer and which comprises a hydraulic control line which is designed to transfer the at least one directional control valve into a first position,

[0008] - with a pilot valve connected to the hydraulic control line,

[0009] - with a pressure supply line, and

[0010] - with a pressure reduction line, wherein the pilot valve is designed to alternately connect the hydraulic control line to the pressure supply line and the pressure reduction line.

[0011] The valve arrangement allows the directional control valve to be safely moved into a blocking position in the event of a leak in the working line and to largely prevent oil from escaping from the leak.

[0012] Preferably, the first position of the at least one directional control valve is a closed position, in which flow is blocked in both directions. The pilot valve can then ensure that the directional control valve remains in the blocked position.

[0013] Preferably, the at least one directional control valve is spring-biased into the first position and has two pilot lines connected to a working chamber opposite the spring, with a first pilot line connected to the pressure line and a second pilot line connected to the working line. The pilot lines enable the directional control valve to be moved into an open position when the hydraulic consumer is actuated. It will be clear to those skilled in the art that the pilot lines or the working chamber can also be active surfaces that cause the directional control valve to move when pressure is applied.

[0014] The pilot valve can be a 3 / 2-way or 4 / 2-way valve. The pilot valve is preferably electrically actuated and, in a rest position, connects the pressure supply line to the hydraulic control line, and, in an actuated position, connects the control line to the pressure reduction line. However, it is also conceivable to control the pilot valve in another way, particularly wirelessly.

[0015] The pilot valve is preferably electrically actuated in a working position and can be de-energized using an emergency stop switch. The emergency stop switch can be arranged in a manually operable work cabin of the machine.

[0016] If the hydraulic consumer has two working lines, such as in the case of a double-acting hydraulic cylinder, the valve arrangement preferably comprises a first directional control valve and a second directional control valve, which are each connected to a pressure line and a working line of the common hydraulic consumer, wherein the hydraulic control lines are connected to one another in such a way that the control lines pilot the two directional control valves into the closed position when they are pressurized by the pilot valve. The directional control valves preferably both have the features mentioned above. By connecting the control lines, both directional control valves are controlled by means of a single pilot valve. It is also conceivable to use two pilot valves. The pilot valves can then be connected electrically or communicate with one another wirelessly, via radio or in some other way.

[0017] In one embodiment, it can be provided that the valve arrangement comprises a shuttle valve with a first blockable inflow and a second blockable inflow as well as with an outflow, wherein the first blockable inflow of the shuttle valve is connected to a first pressure line of the first directional control valve, the second blockable inflow of the shuttle valve is connected to a second pressure line of the second directional control valve and the outflow of the shuttle valve is connected to the pressure supply line, and wherein the shuttle valve is designed such that the pressure line with the highest pressure can be connected to the pressure supply line.

[0018] However, it is also possible to connect the pressure supply line to the pressure line and the working line via branches, whereby the branches are parallel and each have a check valve, which are arranged or designed in such a way that the highest pressure in the lines is directed to the pressure supply line.

[0019] The pressure relief line can be a tank line (return line) that can be connected to a tank.

[0020] However, it is also conceivable for the pressure relief line to be connected to the pressure line and the working line via branches. The branches are parallel and each has a check valve that opens when pressure is applied to the pressure relief line to one of the lines with the lowest pressure, thereby reducing the pressure. This design does not require a return line, which can be advantageous if the valve arrangement is used at a great distance from the superstructure.

[0021] The first directional control valve and / or the second directional control valve may be a 2 / 2-way valve, wherein in the blocking position hydraulic oil flow is blocked in both directions and in a flow position hydraulic oil flow is possible in both directions.

[0022] Furthermore, the use of a previously described valve arrangement in a working line of a hydraulic consumer in a mobile work machine is provided in order to shut off a leak in the working line if it occurs and to largely prevent hydraulic oil from escaping from the leak point.

[0023] Furthermore, a mobile work machine is provided, comprising a substructure, a superstructure, and a boom assembly, as well as a hydraulic system comprising a hydraulic pump, a volume control valve, a hydraulic consumer, and at least two hydraulic lines. The volume control valve is designed to regulate an oil flow through at least one of the hydraulic lines to control the hydraulic consumer. At least one of the hydraulic lines has a directional control valve designed to close the hydraulic line in the event of a leak. The boom assembly can have two or more members, in particular a boom and stick. The directional control valve can be, for example, a slide valve, seat valve, plate valve, or the like.

[0024] The directional control valve is preferably arranged between the volume control valve and the hydraulic consumer, since hydraulic oil can escape from the leak point even when the volume control valve is closed, for example if anti-cavitation valves are used in a bypass bridging the volume control valve to prevent cavitation.

[0025] Preferably, the mobile work machine has a previously described valve arrangement and the directional control valve is part of the valve arrangement.

[0026] In one embodiment, the hydraulic consumer is a hydraulic cylinder, which is particularly double-acting. Then, as described above, a directional control valve is provided in each of the hydraulic lines. It is also conceivable to provide more than one directional control valve or more than one valve arrangement in order to protect the hydraulic lines at different locations. Furthermore, several control sections of the mobile work machine can each have such a valve arrangement, i.e., a plurality of hydraulic lines to different hydraulic consumers can be protected, as needed.

[0027] Furthermore, a method for minimizing hydraulic oil loss in a previously described mobile work machine in the event of a leak in a working line is provided, which method comprises successive steps: a. If a leak occurs in the hydraulic line between the hydraulic consumer and the directional control valve, moving the directional control valve into a blocking position and thereby blocking the hydraulic line, b. Ensuring that the blocking position is assumed until the leak is rectified, c. After the leak has been rectified, transferring the directional control valve and / or the valve arrangement to the initial state before the leak or to an initial position.

[0028] In contrast to other valves or valve assemblies that close off hydraulic lines, this method allows the mobile work machine to continue to be operated and moved except for the control section assigned to the leak line. Since it is ensured, or can be ensured, that the blocking position is maintained until the leak is eliminated and the working line is repaired, hydraulic oil can be reliably prevented from escaping from the working line. Valves that do not have this option are not suitable as an emergency stop device to prevent large quantities of hydraulic oil from escaping from a leak. The directional control valve or valve assembly can be returned to the state it was in before the leak occurred and the line was closed off, preferably without the use of tools and without replacing or renewing parts / components.Particularly preferably, the initial state is automatically initiated, for example, after an operator has given the initial state. Such an initial state may involve an input in an operator unit, the actuation of a switch, or the like.

[0029] Further possible embodiments of the valve arrangement, the working machine and the method are described below.

[0030] Because a valve arrangement for a working machine, in particular a construction machine with oil hydraulic tool, is provided

[0031] - with a first directional control valve, in particular a first 2 / 2-way valve, which is connected to a first pressure line and a first working line, with a second directional control valve, in particular a second 2 / 2-way valve, which is connected to a second pressure line and a second working line, with a 4 / 2-way valve, which is connected to a pre-pressure line, a discharge line, a first control line and a second control line,

[0032] - with a shuttle valve with a first lockable inlet and a second lockable inlet and with an outlet, wherein

[0033] - If the 4 / 2-way valve is electrically operated and, in a rest position, connects the pre-pressure line to the first control line, and in a controlled position, connects the first control line to the discharge line, both the first directional valve and the second directional valve can be closed essentially simultaneously in the rest position of the 4 / 2-way valve. The rest position is preferably de-energized, i.e., can be achieved by means of an emergency stop switch or an electrical shutdown.

[0034] The second control line is preferably permanently blocked and connected to the pre-pressure line in the controlled position of the 4 / 2-way valve.

[0035] Furthermore, if the first lockable inlet of the shuttle valve is connected to the first pressure line, the second lockable inlet of the shuttle valve is connected to the second pressure line, and the outlet of the shuttle valve is connected to the pre-pressure line, both 2 / 2-way valves are closed in the rest position of the 4 / 2-way valve due to the pressure in the higher-pressure pressure line. For this purpose, it is advantageous for the control line to be connected to the first 2 / 2-way valve and the second 2 / 2-way valve in such a way that it pre-controls them to the closed position when the control line is pressurized.

[0036] An emergency stop function can be achieved particularly easily and reliably if the 4 / 2-way valve is electrically operated in a working position and can be de-energized using an emergency stop switch. It is particularly advantageous for the emergency stop switch to be manually operated and located in a work cabin of the machine. The emergency stop function can be provided in the event of a leak in the working line.Because it can be provided in a generic work machine that at least one directional control valve, in particular a 2 / 2-way valve, is assigned to each of the at least two hydraulic lines, which is designed to close the hydraulic line in an emergency, wherein the at least one directional control valve of each of the two hydraulic lines is arranged in the area of ​​the boom in the hydraulic line or in the area of ​​the substructure in the hydraulic line between the valves and the oil-hydraulic tool, in the event of a hydraulic line breaking in the area of ​​the boom, the leakage of hydraulic oil from the upstream hydraulic system of the work machine can be largely prevented.

[0037] The directional control valves are preferably hydraulically pilot-controlled. In particular, they have an opening pressure between 1 bar and 10 bar, in particular between 1.5 bar and 5 bar, and particularly preferably, within the usual tolerances, approximately 2 bar. This keeps the pressure loss relatively low. The directional control valves are further preferably designed for working pressures between 200 bar and 450 bar, preferably between 300 bar and 450 bar, and in particular 350 bar to 420 bar. The pilot valve is preferably designed for working pressures up to 500 bar. Finally, the valve arrangement is preferably designed for a flow rate (volume flow) of 50 liters per minute (l / min) to 2500 l / min, in particular 600 l / min to 1500 l / min, and particularly preferably 700 l / min to 1350 l / min.

[0038] The valve arrangements are preferably modular in design so that, for example, one directional control valve can be mounted on one side of the boom and the other directional control valve on the other side of the boom, regardless of the specific shape of the valve arrangement.

[0039] A particularly advantageous embodiment is one in which the directional control valves of the valve assembly can be connected directly to the shut-off valves or quick-change connections of the work machine, or even replace them. Ball valves are often installed in the area of ​​an excavator's boom, which must be closed to change the attachment. The valve assembly according to the invention can be installed instead of these ball valves, thus providing additional benefits through the automatic closure of the valves when the excavator is shut down and saving working time, in addition to increased operational reliability.

[0040] It's conceivable that the directional control valves are closed by pressing an emergency stop switch and reopened by pressing the emergency stop switch again after the leak has been rectified. However, it's also possible that the directional control valves are automatically controlled by a sensor that detects a pressure drop, or that they close hydraulically fully automatically when the pressure drops.

[0041] If the at least two hydraulic lines of the work machine are located in a protected area on the upper side of the boom, formed by channels or pressure medium pipes, and the respective directional control valve is arranged in this protected area, the likelihood of damage to the hydraulic lines on the pressure side of the valve arrangement and to the valve arrangement itself is reduced, especially during demolition operations. Preferably, the respective directional control valve or 2 / 2-way valve is integrated into a valve block, which can, for example, be flanged to a channel.

[0042] Preferably, the at least two hydraulic lines directly supplying the tool are each attached to the tool at a first attachment point and to the boom at a second attachment point, forming a flexible hose bend between the two attachment points. The at least one directional control valve or 2 / 2-way valve is arranged in the area of ​​the boom outside the flexible hose bend. The two directional control valves are preferably hydraulically and / or electrically connected to each other.

[0043] If the second attachment point of each hose bend is located on the associated directional control valve, additional fittings or passive leak protection devices in this area are not necessary.

[0044] The oil-hydraulic tool is preferably an excavator tool, a demolition shear, a forestry tool, or a civil engineering tool. These tools, and their typical applications, pose a particularly high risk of a line break due to damage during operation. The safety device described above is particularly advantageous when the substructure is self-propelled.

[0045] The emergency that leads to a shut-off of the 2 / 2-way valves is advantageously a breakage of at least one hose bend, in particular in the immediate vicinity of a tool mounted on the handle.

[0046] Preferably, such a working machine has a valve arrangement with the features described above.

[0047] Furthermore, a method for protecting a work machine as described above is proposed, which comprises the following sequential steps: a. If a leak occurs in at least one of the hydraulic lines between the oil-hydraulic tool and the valves, moving the at least one directional control valve or 2 / 2-way valve into a blocking position (rest position) and thereby blocking the at least two hydraulic lines, b. After the leak has been rectified, transferring the at least one directional control valve or 2 / 2-way valve to the starting position.

[0048] This effectively limits the amount of oil escaping in the event of a hydraulic line rupture, even if the hydraulic pump of the work machine continues to pump. Damage to the hydraulic pump caused by idling can thus be prevented. Furthermore, the process promotes occupational safety and can conserve hydraulic oil (resource conservation).

[0049] In particular, the oil-hydraulic tool may comprise a double-acting hydraulic cylinder and the two hydraulic lines connected to the double-acting hydraulic cylinder may be shut off in step b.

[0050] When using a valve arrangement described above in a working machine to prevent uncontrolled oil from escaping from the hose rupture point in the event of a hose rupture in the area of ​​a hose bend of the two working lines, particularly high reliability is ensured with simple control in an emergency.

[0051] Furthermore, a mobile hydraulic construction machine comprising a superstructure, a substructure, a boom assembly, preferably with a boom and intermediate boom as well as with a stick, an attachment connected to the stick, and a hydraulic system for moving the boom assembly and the attachment can be provided. The hydraulic system has at least one pump and one additional valve block, wherein the additional valve block is designed to be able to regulate the oil flow of at least two hydraulic lines connecting the attachment to the pump in order to control the attachment. At least one emergency stop valve is assigned to each hydraulic line, which is designed to close the hydraulic line in an emergency, wherein the at least one emergency stop valve is arranged in the region of the boom assembly in the hydraulic line and / or in the superstructure on the flow side of the additional valve block remote from the pump.The emergency stop valves can be represented by the valve arrangements described above. Emergency stop valves can also include shut-off devices such as gate valves.

[0052] The emergency stop valves allow the hydraulic lines to be closed in the event of a leak, thus largely preventing hydraulic oil from escaping. Retrofitting the emergency stop valves in the superstructure area is particularly easy. The use of emergency stop valves in the stick area is advantageous, as this is extremely useful in the event of a leak in the area between the boom assembly and the attachment.

[0053] Preferably, the at least two hydraulic lines are located in a protected area on the upper side of the boom or are formed by channels, with the respective emergency stop valve located in this protected area. A protected area means that the hydraulic lines are rigid pipes, particularly made of metal, that are protected from external influences. These protected areas must be distinguished from areas of the hydraulic line with flexible hoses, which can easily tear or become damaged.

[0054] The hydraulic lines are preferably each attached to the attachment at a first attachment point and to the boom at a second attachment point, forming a flexible hose bend between the two attachment points. The at least one emergency stop valve is preferably arranged in the area of ​​the boom outside the flexible hose bend. During regular work with the mobile hydraulic construction machine, oil leaks often occur at the flexible hose bends because their nature makes them prone to, for example, getting caught on parts of the construction site. However, the hose bends are essential for the use of the construction machine because, without them, large movements of the boom assembly and attachments would not be possible. Closing the emergency stop valves and thus the hydraulic lines and the hydraulic system prevents further oil from escaping in the event of a leak.

[0055] Preferably, the emergency stop valves are electronically controlled solenoid valves, which are particularly cost-effective. The emergency stop valves can be 2-way valves, as described above, and the hydraulic system preferably includes at least one return line connecting the emergency stop valves to a hydraulic oil tank from which the hydraulic system is supplied by the pump. In this case, it is not necessary to communicate with the auxiliary valve block, since the hydraulic oil flow through the hydraulic lines does not need to be interrupted in the area of ​​the auxiliary valve block.

[0056] In a further preferred embodiment, the mobile hydraulic construction machine comprises an emergency stop actuation device which communicates with the emergency stop valves and / or optionally additionally with the additional valve block and is configured to close the emergency stop valves when actuated.

[0057] Preferably, the emergency stop device is located in a driver's cab of the mobile hydraulic machine. Upon detecting a leak, the driver of the mobile hydraulic construction machine can activate the emergency stop device, thus preventing further hydraulic oil from leaking out at the point of failure.

[0058] Preferably, at least one sensor is assigned to the at least two hydraulic lines, which sensor is configured to detect a leak in the at least two hydraulic lines, wherein the at least one sensor communicates with the emergency stop valves and / or the additional valve block. In this case, the emergency stop valves can be closed automatically in the event of a leak and a pressure drop in the hydraulic line.

[0059] In a preferred embodiment, the mobile hydraulic construction machine is a long-arm boom excavator with a reach height in the range of 15 m to 90 m and, in particular, a weight class between 25 t and 400 t. However, it can also be a mini excavator up to approximately 10 t or a small excavator up to approximately 18 t.

[0060] Furthermore, a method is provided for controlling a mobile hydraulic construction machine having a superstructure, a substructure, a boom assembly with a stick, an attachment connected to the stick, and a hydraulic system for moving the boom assembly and the attachment, wherein the hydraulic system comprises at least one pump and one valve block, in particular an additional valve block, and at least two hydraulic lines connecting the attachment to the pump, wherein the valve block or the additional valve block is connected to the at least two hydraulic lines. The method comprises the following successive steps: a) detecting a leak in one of the hydraulic lines between the attachment and the valve block or additional valve block, b) switching at least one emergency stop valve, which is in each case in the region of the boom assembly and / or in the superstructure on the flow side of the valve block orof the additional valve block is arranged in one of the at least two hydraulic lines, thereby shutting off the at least two hydraulic lines. Preferably, the emergency stop valves are 2-way valves and the hydraulic system comprises at least one return line, and in step b) of the method, the following is provided:

[0061] - Connection of the hydraulic line to the return line by means of the emergency stop valve, whereby the return line is connected to a hydraulic oil tank from which the hydraulic system is fed by means of the pump.

[0062] Preferably, the method comprises the following step between steps a) and b):

[0063] - Actuating the valve block or the additional valve block and thereby shutting off the at least two hydraulic lines, wherein step b) is then carried out with a predetermined time delay.

[0064] Preferably, the method comprises detection by sighting an operator or by a sensor arranged in the hydraulic line.

[0065] Preferably, the mobile hydraulic construction machine comprises an emergency stop device that communicates with the emergency stop valves and / or the valve block or additional valve block, and the method according to step a) comprises the following step:

[0066] - Manual operation of the emergency stop device by the operating personnel.

[0067] The mobile hydraulic construction machine can be designed as described above.

[0068] Preferred embodiments of the invention are explained in more detail below with reference to the drawings.

[0069] The figures show:

[0070] Figure 1 : a spatial representation of a mobile hydraulic

[0071] Construction machine, Figure 2: a plan view of the mobile hydraulic construction machine from Figure 1,

[0072] Figure 3: a schematic representation of an embodiment of a

[0073] Hydraulic system of an attachment of the mobile hydraulic construction machine from Figure 1,

[0074] Figure 4: a schematic representation of another embodiment of a hydraulic system of an attachment,

[0075] Figure 5: a valve arrangement of an embodiment in the blocking position, as well as

[0076] Figure 6: a valve arrangement of a further embodiment in

[0077] Locked position.

[0078] Figure 1 shows a mobile work machine, in particular a hydraulic construction machine 1 in a preferred embodiment as a long-arm boom excavator with a substructure 2 which is connected to a superstructure 4 via a slewing mechanism 3 which can rotate about a slewing axis S. With the help of the slewing mechanism 3, a controlled slewing movement between the superstructure 4 and the substructure 2 about the slewing axis S is possible. In general, a distinction can be made between mobile excavators and crawler excavators. The substructure 2 can have tires in a chassis, which is referred to as a mobile excavator, although mobile excavators are only used in the weight class up to 25 t, and can have tracks, which is why we speak of crawler excavators, which are used in all weight classes. As self-propelled land vehicles, mobile and crawler excavators must be distinguished from other types of excavators, such as floating dredgers.In the preferred embodiment, the long-arm boom excavator 1 is realized as a crawler excavator, which lies in a weight class typical for demolition work between 25 t and 400 t. The superstructure 4 has a driver's cab 5 at its end in the direction of travel F (straight alignment) and a counterweight 6 opposite the driver's cab 5. Figures 1 and 2 show a three-link boom assembly 7, which is attached to the superstructure 4 next to or behind the driver's cab 5. The boom assembly 7 has three consecutive links 8, 9, 10: a first link 8, called the boom, a second link 9, called the intermediate boom, and a third link furthest from the superstructure, which is called the stick 10, wherein two consecutive links are pivotally mounted on one another by means of bolts.The boom assembly 7 further comprises a boom cylinder 11, which can move the first link 8, and an intermediate boom cylinder 12, which can move the second link 9 of the boom assembly 7. Furthermore, a stick cylinder 22 is provided, which can be driven to move the stick 10. An attachment 14 is attached to the free end of the stick 10, through which a stick head pin 13 passes. This connection can preferably be established by a quick coupler. The attachment 14 and the quick coupler can also be pivoted about the pivot axis defined by the stick head pin 13. In this embodiment, the attachment 14 is a gripping tool; however, any hydraulic attachments, such as shears, can be used.

[0079] The mobile hydraulic construction machine 1 comprises a hydraulic system that, among other things, drives the boom cylinder 11 and the intermediate boom cylinder 12, as well as the stick cylinder 22, using hydraulic oil. The hydraulic oil flow and the associated movements are controlled and monitored by a main valve block of the hydraulic system (not shown) located in the superstructure 4. The main valve block comprises valves that regulate the supply of hydraulic oil to one of the hydraulic cylinders. Furthermore, the main valve block is responsible for controlling a hydraulic slewing drive of the slewing gear 3 and a hydraulic travel drive for the tracks of the substructure 2. Also belonging to the hydraulic system and located in the superstructure 4 are an auxiliary valve block 15, a hydraulic oil tank 16, and a hydraulic pump 17.The hydraulic pump 17 delivers the hydraulic oil of the hydraulic system and is connected to the main valve block and the auxiliary valve block 15 via a hydraulic connection. Multiple pumps can be used in the hydraulic system if the output of one pump is insufficient for the required application or if the system is to be designed redundantly. The auxiliary valve block 15 controls and regulates the flow of hydraulic oil to the attachment 14. Hydraulic lines 18 lead from the auxiliary valve block 15 to the attachment 14. Figure 1 shows only one hydraulic line 18; however, depending on the attachment used and the type of construction machine, there may be several, but at least two, hydraulic lines 18. The type of attachment 14 and the movement it can perform define the number of hydraulic lines 18 (used and connected).The hydraulic line 18 is formed in the area of ​​the bolts 19 of the boom assembly 7, between the superstructure 4 and the first link 8, and between the first link 8 and the second link 9, and between the second link 9 and the stick 10, by flexible hose lines that are arranged in an arc shape, also called boom hose bends 20. A flexible hose bend 21 is also formed between a first attachment point on the attachment 14 and a second attachment point on the stick 10. The flexible boom hose bends 20 and the flexible hose bend 21 enable the individual links of the boom assembly 7 to pivot about the longitudinal axis of the bolts 19 without the hydraulic line 18 being interrupted or ruptured. The hose bend 21 and the boom hose bends 20 are formed for each additional hydraulic line 18 not shown here.The parts of the hydraulic line 18 that run centrally along the links of the boom assembly 7, far from the pivot axes or the pins 19, are formed by rigid metal pipes. The ends of the metal pipes are each connected to a flexible hose line to form the hydraulic line 18. The metal pipes represent a protected area in which the hydraulic line 18 is protected from external damage. In the illustrated hydraulic line 18, two emergency stop valves 23, 24 are located between the additional valve block 15 and the attachment 14. The emergency stop valves 23, 24 of the at least two hydraulic lines 18 are divided into first emergency stop valves 23 and second emergency stop valves 24 and are schematically shown as a rectangle in Figure 1. The first emergency stop valve 23 and the second emergency stop valve 24 can close the corresponding hydraulic line 18 at the respective position.This ensures that the emergency stop valve 23, 24 located on the side closest to the auxiliary valve block in the event of an oil leak prevents the hydraulic oil located between this emergency stop valve 23, 24 and the hydraulic pump 17 or the hydraulic oil tank 16 in the hydraulic lines 18 from escaping. The first emergency stop valve 23 is located in the superstructure 4 on the flow side of the auxiliary valve block 15 remote from the pump. The second emergency stop valve 24 is located in the hydraulic line 18 in the area of ​​the boom 10 outside the hose bend 21. A position that is located in the flow direction immediately upstream or downstream of the flexible hose line in the area of ​​the boom head bolt 13 is particularly preferred, as shown in Figure 1. Experience has shown that leaks in the hose lines frequently occur in the area of ​​the boom head bolt 13.The previously described position of the second emergency stop valve 24 makes it possible to maintain the maximum possible amount of hydraulic oil in the hydraulic lines 18 in the event of such a leak. If an oil leak occurs in the hose bend 21, closing the second emergency stop valve 24 allows the oil in the hydraulic line 18 between the second emergency stop valve 24 and the additional valve block 15 to remain in the hydraulic lines 18, preventing any leakage. It is conceivable to use additional emergency stop valves, for example, to protect against leakage of the boom hose bends 20 of the second link 9. At least one emergency stop valve 23, 24 is required per hydraulic line 18. Even the first emergency stop valve 23 prevents the majority of the hydraulic oil from escaping in the event of a leak in the flexible hose line in the area of ​​the boom head pin 13.The emergency stop valves 23, 24 are clearly different from conventional pipe rupture safety devices, which are now standard equipment in mobile hydraulic construction machinery. The pipe rupture safety devices (not shown) are installed on the attachment 14 and, in the event of a pipe rupture, prevent uncontrolled movements of the attachment 14 in order to protect operating personnel and construction site personnel. They maintain the pressure of the hydraulic oil in the attachment 14 or the working chambers of the hydraulic cylinders installed therein and allow the attachment 14 to remain in a rigid position. The emergency stop valves 23, 24 interrupt the hydraulic system at at least one point to the auxiliary valve block 15. The hydraulic oil in the hydraulic line between the rupture point and the emergency stop valve 23, 24 escapes. However, the emergency stop valve 23, 24 prevents the escape of large quantities of hydraulic oil and thus contributes to environmental protection during demolition work.

[0080] Figure 3 shows part of a merely schematically illustrated hydraulic system used to control the movement of the attachment 14. The hydraulic valves of the auxiliary valve block 15 are electrically pilot-controlled to move the attachment 14, which is not shown in the figure. The hydraulic pump 17 supplies the auxiliary valve block 15 with the required oil pressure to control the attachment 14 or its hydraulic cylinder. The auxiliary valve block 15 regulates the volume flow of the hydraulic oil through the four exemplary hydraulic lines 18 and can thus control the movement of the attachment 14. A first emergency stop valve 23 and a second emergency stop valve 24 are provided for each hydraulic line 18. The first emergency stop valves 23 and the second emergency stop valves 24 are each located in two different sections of the hydraulic line 18.The boom hose bends 20 closest to the additional valve block and the flexible hose bends 21 in the area of ​​the stick head bolt 13 are shown.

[0081] Firstly, the first emergency stop valves 23 are arranged in the superstructure 4, in a superstructure section of the respective hydraulic line 18, which is located on the flow side of the additional valve block 15 remote from the pump. Secondly, the second emergency stop valves 24 are arranged in a boom assembly section of the respective hydraulic line 18, which is located outside the superstructure 4 and in the area of ​​the boom 10 outside the flexible hose bends 21, as already described above. The emergency stop valves 23, 24 are open during regular operation of the mobile hydraulic construction machine 1, so that the hydraulic oil can flow unhindered through the emergency stop valves 23, 24. The emergency stop valves 23, 24 are controlled by an emergency stop actuation device 25. When the emergency stop actuation device 25 is actuated, the hydraulic lines 18 are closed by means of the emergency stop valves 23, 24, and the hydraulic oil flow is stopped.The emergency stop device 25 communicates electronically with the additional valve block 15 and switches the emergency stop valves 23,24.

[0082] After a leak is detected in one of the hydraulic lines 18 between the attachment 14 and the auxiliary valve block 15, the emergency stop valves 23, 24 are activated and the hydraulic lines 18 are shut off. Figure 3 shows the closed state of the emergency stop valves 23, 24, which is achieved by actuating the emergency stop actuation device 25.

[0083] In a preferred embodiment, the emergency stop valves 23, 24 are electronically controlled solenoid valves.

[0084] In a preferred embodiment, the leak is detected by the operating personnel, who then actuates the emergency stop device 25, and the emergency stop valves 23, 24 are switched and shut off the hydraulic lines 18. Detection can also be performed by a sensor associated with the hydraulic lines 18, and the emergency stop device 25 can then be actuated automatically.

[0085] In a preferred embodiment, the additional valve block 15 is first activated by actuating the emergency stop actuation device 25, and the additional valve block 15 shuts off the at least two hydraulic lines 18. Subsequently, the emergency stop valves 23, 24 are switched with a predeterminable time delay, and the hydraulic lines 18 are closed.

[0086] Figure 4 shows a further embodiment of a part of the hydraulic system, largely analogous to Figure 3. In this case, the attachment 14 is hydraulically pilot-controlled by a low-pressure line. The boom hose bends 20 and the hose bends 21 have been omitted. The differences are discussed below. In the embodiment shown in Figure 4, the first emergency stop valves 23 in the superstructure section of the hydraulic lines 18 are implemented as 2-way valves 26, which can be connected to the hydraulic oil tank 16 of the hydraulic system via a return line 27. During regular operation, the second emergency stop valves 24, which in one embodiment are electronically controlled solenoid valves, are open in the boom assembly section, and the 2-way valves 26 in the superstructure section are in a first switching position, which allows hydraulic oil to flow from the additional valve block 15 via the hydraulic line 18 to the attachment 14.

[0087] After an oil leak has been detected by operating personnel or a sensor, the second emergency stop valves 24 in the boom assembly section of the hydraulic lines 18 are switched and closed by actuating the emergency stop device 25 and the 2-way valves 26 switch to a second switching position shown, in which hydraulic oil flows from the additional valve block 15 via the return line 27 into the hydraulic oil tank 16.

[0088] It is conceivable to use more than two emergency stop valves 23,24 per hydraulic line 18.

[0089] In both versions of the hydraulic systems, one electrically and one hydraulically pilot-controlled, oil leakage can be detected by operating personnel or a sensor. The emergency stop actuation device 25 can, for example, be designed as an actuation button in the driver's cab 5 or on the boom assembly 7, or it can be accessible via a control system of the mobile hydraulic construction machine 1, which has the necessary operating elements for controlling the mobile hydraulic construction machine 1. By actuating the emergency stop actuation device 25, the emergency stop valves 23, 24 are switched and the hydraulic oil flow is stopped. By actuating the emergency stop actuation device 25 again, the emergency stop valves 23, 24 can be switched back and the hydraulic lines 18 to the attachment 14 can be reopened. The emergency stop valves 23, 24 are switched back when the oil leak in the hydraulic lines 18 has been rectified.If the leak is detected by a sensor, it is conceivable that an alarm will be triggered, whereupon the operating personnel can activate the emergency stop device 25. However, it is also possible for the emergency stop valves 23, 24 and / or the additional valve block 15 to be automatically controlled by the sensor that detects a pressure drop. In a further embodiment, it is provided to use emergency stop valves that close automatically when the pressure drops in the hydraulic line 18.

[0090] Finally, Figure 5 shows a valve arrangement with two emergency stop valves. The valve arrangement comprises a first 2 / 2-way valve 30, which is connected to a first pressure line PI and a first working line A1, a second 2 / 2-way valve 31, which is connected to a second pressure line P2 and a second working line A2, a 4 / 2-way valve 32, which is shown here in an assembly with the second 2 / 2-way valve 31 and which is connected to a pre-pressure line Pa, a drain line T, a first control line C, and a blocked connection D, as well as a shuttle valve 33 with a first blockable inlet 34 and a second blockable inlet 35, as well as with an outlet 36. The 2 / 2-way valves are emergency stop valves within the meaning of the above description and can be used and employed accordingly.

[0091] The 4 / 2-way valve 32 is electrically actuated via an electrical line 37 and, in the rest position shown in Fig. 5, connects the pre-pressure line Pa to the first control line C and the drain line T to the permanently blocked port D of the 4 / 2-way valve 32. In an electrically actuated position, the pre-pressure line Pa is connected to the permanently blocked port D and is thus blocked. The control line C is connected to the drain line T and is thus essentially depressurized.

[0092] The control line C is connected to the first 2 / 2-way valve 30 and the second 2 / 2-way valve 31 in such a way that it pilots them into the closed position when the control line C is pressurized.

[0093] The 2 / 2-way valve 30 and the 2 / 2-way valve 31 are preloaded into the closed position (NC) by a spring 39 in the illustrated rest position. Both valves are controlled by the pre-pressure in the connecting lines P1 and P2 and the working lines A1 and A2. For this purpose, a pilot line 40 is provided in the 2 / 2-way valve 30, which runs from the pressure line P1 to a working chamber (not shown) opposite the spring 39; another pilot line 41 runs from the working line A1 to the same working chamber. The spring 39 and the geometric design of the movable valve member and the working chamber (not shown) are selected such that the 2 / 2-way valve 30 switches to the open position against the force of the spring 39 at a pre-pressure of approximately 2 bar. Electrical actuation of the directional valve 30 is neither required nor provided. It is purely pressure-controlled.The same applies to the 2 / 2-way valve 31, in which a pilot line 43 runs from the pressure line P2 and a pilot line 44 from the working line A2 to a corresponding working chamber. This valve is also pressure-controlled and opens, for example, at an applied pre-pressure of 2 bar.

[0094] In the rest position shown in Figure 5, both 2 / 2-way valves 30 and 31 are closed. If pressure builds up in the pressure lines PI or P2, the respective 2 / 2-way valve is piloted into the open position via the pilot lines 40 and 43 respectively. At the same time, however, the higher pressure is applied to the outlet 36 of the shuttle valve 33 via the ports 34 and 35 respectively of the shuttle valve 33. This higher pressure is then available at the pre-pressure line Pa and is passed via the 4 / 2-way valve 32 in the rest position to the control line C, which in turn directs this higher pressure to the spring side of the 2 / 2-way valves 30 and 31 and thus pilots the movable valve elements of the 2 / 2-way valves 30 and 31 into the closed position. The respective control surfaces of the 2 / 2-way valves 30 and 31 are dimensioned so that with the same pressure in the control line C and in the pilot lines 40 and 43, the 2 / 2-way valves 30 and 31 respectively.31 remain closed.

[0095] In order to be able to operate the work machine from this position of the valve arrangement with a hydraulic tool 47 connected to the working lines A1 and A2, the electrical line 37, in which a normally closed emergency stop switch 45 is also connected in series, is supplied with an operating voltage of, for example, 24 V. This switches the 4 / 2-way valve 32 to the working position, in which the control line C is connected to the outlet T and the pre-pressure line Pa is connected to the blocked connection D. If pressure is now applied from the hydraulic system of the work machine, for example to the pressure line PI, the 2 / 2-way valve is pressurized with the corresponding pressure via the pilot line 40. The shuttle valve 33 then directs this pressure, as described above, to the outlet 36 and the pre-pressure line Pa, which, however, is switched to connection D in the 4 / 2-way valve 32 and is thus blocked.Control line C is connected to drain T and is therefore depressurized. This means that there is no pressure in control line C that would counteract the opening of the 2 / 2-way valve 30. The 2 / 2-way valve 30 switches to the open position. A return flow from the hydraulic unit 47 results in a pressure increase in the working line A2. This pressure increase causes the 2 / 2-way valve 31 to open via the pilot line 44, so that the valve arrangement described above is hydraulically permeable and the hydraulic unit 47 can be operated as usual.

[0096] The same applies in the reverse case. If the pressure line P2 is first pressurized with hydraulic pressure, the 2 / 2-way valve 31 opens first, and then, due to the pressure increase in the working line Al, the 2 / 2-way valve 30 also opens.

[0097] The valve arrangement can, for example, be attached to a boom or stick of an excavator. The pressure lines PI and P2 can then be permanently mounted as pipelines on the boom or stick and connected to the valve arrangement. The valve arrangements can each be designed as a valve block. The valve blocks are preferably each attached to one side of the boom or stick. For example, where ball valves are conventionally attached. Flexible hose bends 48 and 49, which are indispensable for movable hydraulic units 47, run from the valve arrangement to the hydraulic unit 47. If, during operation, as described in more detail above, a hose bend 48, 49 gets caught on a protruding rebar, for example during the demolition of a building, and thereby breaks off, a large quantity of hydraulic oil would escape from the break point in conventional hydraulic systems.In such a case, the operator of the work machine can activate the emergency stop switch 45 and thus de-energize the 4 / 2-way valve 32. It then falls into the rest position shown in Figure 5. If the pressure in the hydraulic line falls below the opening pressure of the 2 / 2-way valve due to the leak, the valve closes automatically. Any hydraulic pressure generated by the hydraulic system in the pressure lines Pl or P2 is then applied to the shuttle valve 33. The higher of the two pressures is applied to the shut-off 36 and forwarded to the control line C. The control line C then, together with the spring force of the springs 39, brings both 2 / 2-way valves 30 and 31 into the closed position. As a result, if a hose bend 48, 49 breaks and the emergency switch 45 is activated, the hydraulic system in the valve arrangement is completely closed, so that no further hydraulic fluid can escape from the hydraulic system.

[0098] It should be emphasized here that the valve arrangement does not replace the function of a conventional hose rupture valve, which can additionally be provided directly at the two connections of the hydraulic unit 47, for example, to prevent a boom or a suspended load from suddenly falling if a hose bend 48, 49 breaks. Such hose rupture valves automatically respond to a high volume flow that exceeds specified limits. They are essentially automatic, volume flow-controlled check valves. However, in the event of a hose rupture, these cannot prevent large quantities of hydraulic fluid from escaping from the hydraulic system itself if a hose bend 48, 49 breaks.

[0099] The 2 / 2-way valves 30 and 31 can be of identical construction, but they are preferably selected so that one of the 2 / 2-way valves has a larger opening cross-section than the other in order to be adapted to the different volume flows, for example in double-acting hydraulic units.

[0100] Figure 6 shows a schematic representation of another valve arrangement with emergency stop valves. A double-acting hydraulic cylinder 50 of a hydraulic consumer has two chambers. A first chamber 51 is connected to a first working line 52. A second chamber 53 is connected to a second working line 54. The two working lines 52, 54 are connected on the superstructure side to a volume control valve (not shown), which controls a volume flow through the working lines 52, 54. The volume control valve can be part of the additional valve block. The valve arrangement shown comprises a first 2 / 2-way valve 55, which has a port P connected to a first pressure line 56 and a port A connected to the first working line 52. In a first position of the 2 / 2-way valve 55, the flow from port A to P and from port P to A is blocked.In the second position, the valve 55 allows free flow from A to P and vice versa from P to A. The 2 / 2-way valve 55 is preloaded in the illustrated first position (rest position, closed position) by means of a spring 57. The 2 / 2-way valve 55 has a control line 58 which is connected to a pilot valve 59. The control line 58 is connected to a working chamber located on the side of the spring 57 (shown as a rectangle). Depending on the technical implementation, the spring 57 can be located in the working chamber. The 2 / 2-way valve 55 is also controlled via the pre-pressure in the first pressure line 56 and the first working line 52. For this purpose, a pilot control line 60 is provided in the 2 / 2-way valve 55, which runs from the first pressure line 56 to a working chamber opposite the spring 57. This is a schematic representation. The pilot line 60 can be an effective surface of the piston of the directional control valve.A further pilot line 61 runs from the first working line 52 to the same working chamber. Here, too, an active surface of the directional control valve can be connected to the first working line in order to implement the functionality shown schematically. The spring 57 and the geometric design of the movable valve member are selected such that the 2 / 2-way valve 55 switches to the open position against the force of the spring 57 at a pre-pressure of approximately 2 bar in the first working line 52 or the first pressure line 56. Electrical actuation of the 2 / 2-way valve 55 is neither required nor provided. It is purely pressure-controlled. The 2 / 2-way valve 55 can be moved to the second, closed position by actuation via the control line 58. The closing pressure of the spring is approximately 4-6 bar, preferably 2 bar.

[0101] The pilot valve 59 connected to the control line 58 can be designed as a 3 / 2-way valve. However, it is also conceivable to use a 4 / 2-way valve. Shown is a 3 / 2-way valve which, in a first position, has a first port A1 which is switched off and connected to a pressure reduction line 62. A second port A2 is connected to a control line 63 which controls a second 2 / 2-way valve 64 and is connected in a branch to the control line 58 of the first 2 / 2-way valve 55. Both 2 / 2-way valves 55, 64 are thus controlled by means of the second port A2. The second 2 / 2-way valve 64 is designed analogously to the first 2 / 2-way valve 55 and is located between the second pressure line

[0102] 65 and the second working line 54. The control line 63 of the second 2 / 2-way valve 64 acts analogously in the direction of action of the spring and moves the valve 64 to the closed position when pressure is applied to the control line 63.

[0103] A third port A3 of the pilot valve 59 is connected to a pressure supply line 66. In the first position of the 3 / 2-way valve, hydraulic oil flow is permitted from port 3 to port 2. The control line 63 is pressurized with hydraulic oil pressure from the pressure supply line 66. In a second position of the 3 / 2-way valve, port 3 is blinded and hydraulic oil flow is permitted from port 2 to port 1. Pressure is reduced in the control line 63 and thus also in the control line 58, and the hydraulic oil flows into the pressure reduction line 62. The pilot control valve 59 is preloaded in the first position by a spring. The pilot control valve 59 is electrically actuated via an electrical line 67. A normally closed emergency stop switch 68 is connected in series in the electrical line 67 and is supplied with an operating voltage of, for example, 24 V.This switches the pilot valve 59 into the working position in which the control line 63 is connected to the pressure reduction line 62 and the pressure supply line.

[0104] 66 (also called the pre-pressure line) is connected to the blocked port A3. Furthermore, the pilot control valve 59 has an optional emergency manual override, which is designed such that the pilot valve 59 can be moved into the working position by actuating the emergency manual override.

[0105] Figure 6 shows the first position and not the working position of the pilot valve 59.

[0106] In the rest position shown in Figure 6, the two 2 / 2-way valves 55 and 64 are closed. If there is pressure in the pressure lines 56 or

[0107] 65, the respective 2 / 2-way valve 55, 64 is piloted into the open position via the respective pilot line 60 or 69. At the same time, however, the highest pressure present at the four ports AI, A2, PI, P2 of the two 2 / 2-way valves is passed via the pressure supply line 66 to port A2 of the pilot valve 59 and thus to the control lines 58, 63, which in turn directs this higher pressure to the spring side of the 2 / 2-way valves 55 and 64 and thus pilots the movable valve elements of the 2 / 2-way valves 55 and 64 into the closed position. The respective control surfaces of the 2 / 2-way valves 55 and 64 are dimensioned such that when the pressure in the control lines 58,63 and the pilot lines 60,61 and 69,70 is the same, the 2 / 2-way valves 55 and 64 remain closed.

[0108] The pressure supply line 66 is connected to the two working lines 52, 54 and the two pressure lines 56, 65. The branches to the four lines 52, 54, 56, 65 are arranged in parallel, with a check valve 71 arranged in each of the branches, which opens in the direction of the pressure supply line 66 when a higher pressure is applied. If, for example, the pressure line 56 is subjected to the highest pressure, the check valve 71 in the line branching off from the pressure line 56 opens and the check valves 71 arranged parallel to it are thereby closed, since the pressures present there are lower. The hydraulic oil pressure of the pressure line 56 is fed into the pressure supply line

[0109] 66 and the pressure is available for the control lines 63,58, as explained above.

[0110] In order to operate the working machine from this position of the valve arrangement with a hydraulic consumer 50 connected to the working lines 52 and 54, the electrical line 67 is supplied with operating voltage and the 3 / 2-way valve 59 is switched to the working position. If pressure is now applied from the hydraulic system of the working machine, for example to the pressure line 56, the 2 / 2-way valve 55 arranged in the line is pressurized with the corresponding pressure via the pilot line 60. The check valve 71 assigned to the pressure line then transmits this pressure, as described above, to the pressure supply line 66, which, however, is switched to port A3 in the pilot valve 59 and is thus blocked. The control line 63 is connected to the pressure reduction line 62.To depressurize the control line, the pressure relief line 62 is connected to the two working lines 52, 54 and the two pressure lines 56, 65. The branches to the four lines 52, 54, 56, 65 are arranged in parallel, with a check valve 72 arranged in each of the branches, which opens toward the respective one of the four lines 52, 54, 56, 65 when a higher pressure is applied. If, for example, the pressure reduction line 62 is subjected to a pressure which is higher than the pressure in the pressure line 65, the check valve 72 in the line branching off from the pressure line 65 opens and the pressure in the control lines 63, 58 can be reduced, so that in the control lines 63, 58 there is at least a lower pressure than in the working line 56, which would counteract the opening of the 2 / 2-way valves 55, 64.For example, if a backflow occurs from the hydraulic consumer 50, which leads to a pressure increase in the working line 54, this pressure increase causes the 2 / 2-way valve 64 to open via the pilot line 70, so that the valve arrangement described above is hydraulically permeable and the hydraulic consumer can be operated as usual.

[0111] The same applies in the reverse case. If the pressure line 65 is first pressurized with hydraulic pressure, the 2 / 2-way valve 64 opens first, and then, due to the pressure increase in the working line 52, the 2 / 2-way valve 55 also opens.

[0112] The valve arrangement can, for example, be attached to a superstructure of the mobile work machine or, in the case of an excavator, to a boom or stick. The pressure lines 56 and 65 can then be permanently mounted as pipelines on the boom or stick and connected to the valve arrangement. The valve arrangements can each be designed as a valve block. The valve blocks are preferably each attached to one side of the boom or stick. For example, where ball valves are conventionally attached. It is also conceivable to arrange the valve arrangement in the superstructure. Depending on the design of the hydraulic consumer, one or more working lines are provided. The hydraulic consumer can, for example, also be the boom cylinder 11, the intermediate boom cylinder 12 or the stick cylinder.

[0113] Flexible hose lines run in a curved shape from the valve assembly to the hydraulic consumer 50. These sections are called flexible hose bends and differ from pipe bends, which are purchased as components and have a fixed, rigid geometry. The flexible hose bends are indispensable for movable hydraulic units. If, during operation, as described in more detail above, a hose bend gets caught on a protruding rebar, for example during the demolition of a building, and thereby breaks, a large quantity of hydraulic oil would escape from the break point in conventional hydraulic systems. In such a case, the operator of the work machine can activate the emergency stop switch 68 and thus de-energize the pilot valve 59. It then falls into the position shown in Figure 6. If the pressure in the hydraulic line falls below the opening pressure of the 2 / 2-way valve due to the leak, the valve closes automatically.The higher of the two pressures in pressure lines 56 and 65 and the leak-free working line is applied to the pressure supply line 66 and forwarded to the control lines 58, 63. The control lines 58, 63, together with the spring force of the springs 57, then move both 2 / 2-way valves 55, 64 to the closed position. As a result, in the event of a leak in a working line, for example, if a flexible hose bend breaks and the emergency switch 68 is activated, the hydraulic system in the valve arrangement is completely sealed off, so that no further hydraulic fluid can escape from the hydraulic system.

[0114] It should be emphasized here that the valve arrangement does not replace the function of a conventional hose rupture valve, which can additionally be provided directly at the two connections of the hydraulic unit 50, for example, to prevent a boom or a suspended load from suddenly falling if a hose bend breaks. Such hose rupture valves respond automatically to a high volume flow that exceeds specified limits. They are essentially automatic, volume flow-controlled check valves. However, in the event of a hose rupture, these cannot prevent large quantities of hydraulic fluid from escaping from the hydraulic system itself if a hose bend breaks.

[0115] The two 2 / 2-way valves 55,64 can be of identical construction, but they are preferably selected so that one of the 2 / 2-way valves has a larger opening cross-section than the other in order to be adapted to the different volume flows, for example in double-acting hydraulic units or return-sensitive attachments (e.g. hydraulic hammers).

Claims

Patent claims Valve arrangement for a mobile working machine (1) with a hydraulic consumer (47, 50), - with at least one directional control valve (30, 31, 55, 64) connected to a pressure line (Pl, P2, 56, 65) and a working line (Al, A2, 52, 54) of the hydraulic consumer (47, 50) and comprising a hydraulic control line (C, 58, 63) designed to move the at least one directional control valve (30, 31, 55, 64) into a first position, - with a pilot valve (32,59) connected to the hydraulic control line (C,58,63), - with a pressure supply line (Pa, 66), and - with a pressure relief line (T, 62), wherein the pilot valve (32, 59) is designed to alternately connect the hydraulic control line (C, 58, 63) to the pressure supply line (Pa, 66) and the pressure relief line (T, 62). Valve arrangement according to claim 1, characterized in that the first position of the at least one directional control valve (30, 31, 55, 64) is a closed position and the flow in both directions is blocked. Valve arrangement according to one of the preceding claims, characterized in that the at least one directional control valve (30, 31, 55, 64) is spring-biased into the first position and has two pilot lines (40, 41, 43, 44, 60, 61, 69, 70) which are connected to a working chamber opposite the spring (39, 57), wherein a first pilot line (40, 43, 60, 69) is connected to the pressure line (Pl, P2, 56, 65) and a second pilot line (41, 44, 61, 70) is connected to the working line (Al, A2, 52, 54) is connected.

4. Valve arrangement according to one of the preceding claims, characterized in that the pilot valve (32, 59) is a 3 / 2 or 4 / 2-way valve.

5. Valve arrangement according to one of the preceding claims, characterized in that the pilot valve (32, 59) is electrically actuated and in a rest position connects the pressure supply line (Pa, 66) with the hydraulic control line (C, 58, 63) and in an actuated position connects the control line (C, 58, 63) with the pressure relief line (T, 62).

6. Valve arrangement according to one of the preceding claims, characterized in that the pilot valve (32, 59) is electrically actuated in a working position and can be de-energized by means of an emergency stop switch (45, 68).

7. Valve arrangement according to claim 6, characterized in that the emergency stop switch (45, 68) is arranged in a work cabin of the machine and can be operated manually.

8. Valve arrangement according to one of the preceding claims, characterized in that the valve arrangement comprises a first directional control valve (30, 55) and a second directional control valve (31, 64), each of which is connected to a pressure line (Pl, P2, 56, 65) and a working line (Al, A2, 52, 54) of a common hydraulic consumer (47, 50), wherein the hydraulic control lines (C, 58, 63) are connected to each other in such a way that the control lines (C, 58, 63) pre-control the two directional control valves to the closed position when they are pressurized.

9. Valve arrangement according to claim 8, characterized in that the valve arrangement comprises a changeover valve (33) with a first lockable inlet (34) and a second lockable inlet (35) as well as with an outlet (36), wherein the first lockable inlet (34) of the The changeover valve is connected to a first pressure line (PI) of the first directional control valve (30), the second lockable inlet (35) of the changeover valve is connected to a second pressure line (P2) of the second directional control valve (31), and the outlet (36) of the changeover valve is connected to the pressure supply line (Pa), and the changeover valve (33) is designed such that the pressure line (P1,P2) with the highest pressure can be connected to the pressure supply line (Pa).

10. Valve arrangement according to one of the preceding claims 1 to 8, characterized in that the pressure supply line (66) is connected via branches to the pressure line (56, 65) and the working line (52, 54), wherein the branches are parallel and each has a check valve (71) arranged such that the highest pressure present in the lines (52, 54, 56, 65) is directed to the pressure supply line (66).

11. Valve arrangement according to one of the preceding claims, characterized in that the pressure relief line (T) is a tank line connectable to a tank.

12. Valve arrangement according to one of the preceding claims 1 to 10, characterized in that the pressure relief line (62) is connected via branches to the pressure line (56, 65) and the working line (52, 54), wherein the branches are parallel and each has a check valve (72) which, when pressurized in the pressure relief line (62), opens to one of the lines (52, 54, 56, 65) with lower pressure.

13. Valve arrangement according to one of the preceding claims, characterized in that the first directional control valve (30, 55) and / or the second directional control valve (31, 64) is a 2 / 2-way valve.

14. Use of a valve arrangement according to one of the preceding claims in a working line of a hydraulic consumer (47, 50) in a mobile working machine in order to shut off the working line (52, 54, Al, A2) in the event of a leakage and to largely prevent hydraulic oil leakage from the leak point. Mobile working machine (1) comprising a substructure (3), a superstructure (4) and a boom assembly (7), as well as a hydraulic system comprising a hydraulic pump (17), a volume control valve, a hydraulic consumer (47, 50) and at least two hydraulic lines (18, 52, 54, 56, 65, Al, A2, Pl, P2), wherein the volume control valve is designed to be able to regulate an oil flow through at least one of the hydraulic lines (18, 52, 54, Al, A2) for controlling the hydraulic consumer (47, 50), characterized in that the at least one of the hydraulic lines (18, 52, 54, 56, 65, Al, A2, Pl, P2) has a directional control valve (30, 31, 55, 64) designed to close the hydraulic line (18, 52, 54, 56, 65, Al, A2, Pl, P2) in the event of a hydraulic line leak. Mobile working machine according to claim 15, characterized in that the directional control valve (30, 31, 55, 64) is arranged between the volume control valve and the hydraulic consumer (47, 50). Mobile working machine according to claim 15 or 16, characterized in that the mobile working machine comprises a valve arrangement according to one of the preceding claims and the directional control valve (30, 31, 55, 64) is part of the valve arrangement. Method for minimizing hydraulic oil loss in a mobile working machine (1) according to one of claims 15 to 17 in the event of leakage of a working line (52, 54, Al, A2), comprising successive steps: a.If a leak occurs in the hydraulic line (52, 54, Al, A2) between the hydraulic consumer (47, 50) and the directional control valve (30, 31, 55, 64), move the directional control valve (30, 31, 55, 64) into a closed position and thereby shut off the hydraulic line (52, 54, Al, A2). b. Ensure that the closed position is maintained until the leak is rectified, c. After the leak is rectified, return the directional control valve (30, 31, 55, 64) and / or the valve assembly to an initial state prior to the leak.

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