Mobile work machine with emergency stop function in the event of a leak of the working line

Abstract

The invention relates to a mobile work machine (33) having a substructure (34), a superstructure (36), and a boom assembly (39) and to a hydraulic system comprising a hydraulic pump (3), a working line (8, 10), a hydraulic load (5), a volume control valve (7) that is designed to be able to regulate an oil flow of the working line (8, 10), which is connected to the load (5), in order to actuate the load (5), and a bypass (20, 21) that can bridge the volume control valve (7). A feed device (23) with a feed function is arranged in the bypass (20, 21) such that when the working line (8) has a high pressure, the bypass (20) is closed, and when the working line (8) has a low pressure, the bypass (20) is opened, and the working line (8) or the hydraulic load (5) connected to the working line (8) can be supplied with hydraulic oil via a supply line (12), wherein the feed device (23) has an emergency stop function or the hydraulic system comprises an emergency stopping device (32) which is designed to close the line in the bypass (20) or the supply line (12) if a leak is ascertained in the working line (8).

Description

[0001] Mobile work machine with emergency stop function in case of leakage of the work line

[0002] The present invention relates to a mobile work machine having the features of the preamble of claim 1, a use of a valve or a shut-off device in a mobile work machine having the features of the preamble of claim 10 and a method for minimizing hydraulic oil loss in a mobile work machine in the event of a leak in a working line.

[0003] Mobile work machines with hydraulic systems, especially mobile hydraulic work machines such as 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. In the demolition sector, so-called long-arm boom excavators (also known as "long-arm") or demolition excavators are used. The long booms and sticks make mobile hydraulic construction machines a suitable tool for using hydraulic attachments for the respective purpose, even at heights of over 20 m.When operating mobile hydraulic construction machinery, the hydraulic hoses that make up the hydraulic system of the attachments or the hydraulic cylinders on the boom are exposed to external influences due to aging processes or weather conditions, which can cause damage to the hydraulic hoses. Further, much more unpredictable sources of damage include external mechanical impacts on the hydraulic hoses caused by working in areas that are not entirely transparent. The excavator operator cannot see every part of the boom of the mobile hydraulic construction machinery during operation, meaning that hydraulic hoses can become caught on sharp objects on the construction site, punctured, torn off, cut open, or crushed, thus resulting in damage.Due to unavoidable aging processes on the one hand and unforeseeable external influences on the other, oil leaks can occur in the hydraulic hoses during normal operation of the mobile work 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 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 must be routed 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 often 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 a considerable risk to people.

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

[0005] The invention is therefore based on the object of specifying a mobile work machine in which the hydraulic system is designed to minimize hydraulic oil loss in the event of a leak in a working line, as well as providing a use of a valve or a shut-off device in a mobile work machine and a method for minimizing hydraulic oil loss in a mobile work machine in the event of a leak in a working line. This object is achieved by a mobile work machine having the features of claim 1 and by using a valve or a shut-off device in a mobile work machine having the features of claim 10 and a method for minimizing hydraulic oil loss in a mobile work machine in the event of a leak in a working line having the features of claim 11.

[0006] Accordingly, a mobile work machine having a substructure, a superstructure and a boom assembly, as well as a hydraulic system comprising a hydraulic pump, a working line, a hydraulic consumer, a volume control valve which is designed to be able to regulate an oil flow of the working line connected to the consumer in order to control the consumer, and a bypass which can bridge the volume control valve, wherein a replenishment device with a replenishment function or replenishment function is arranged in the bypass such that when the working line carries excess pressure, the bypass is closed and when the working line carries low pressure, the bypass is open and the working line or the hydraulic consumer connected to the working line can replenish or replenish hydraulic oil via a supply line.The replenishment device has an emergency stop function, or the hydraulic system includes an emergency stop device, each of which is designed to close the line in the bypass or the supply line if a leak is detected in the working line. "Replenishment" means that hydraulic oil flows through the supply line; this can occur, for example, through replenishment or due to dynamic pressure. The boom assembly can have two or more links, in particular a boom. The boom assembly preferably has a boom and a stick, wherein the stick can carry a (hydraulic) attachment.

[0007] The emergency stop function or emergency stop device ensures that even a shut-off (blocked) working line is no longer supplied with hydraulic oil, preventing hydraulic oil from leaking out, even if the hydraulic pump of the work machine continues to pump. This prevents damage to the hydraulic pump due to idling. Furthermore, the process promotes occupational safety and can conserve hydraulic oil (resource conservation). All other functions of the mobile work machine, especially an excavator, remain available. The work machine does not have to be completely shut down. This offers significant advantages.

[0008] The emergency that leads to a shut-off or an emergency stop is a leak in a previously described working line, advantageously a rupture of at least one flexible hose bend, in particular in the immediate vicinity of a tool mounted on the boom assembly or in the immediate vicinity of a hydraulic working cylinder of the boom assembly.

[0009] Preferably, the hydraulic consumer is a hydraulic cylinder that causes movement of the boom assembly and / or an oil-hydraulic attachment. The hydraulic cylinder can, for example, be the stick cylinder, bucket cylinder, boom cylinder, intermediate boom cylinder, or the hydraulic unit of an attachment. In particular, the hydraulic unit of an attachment is an oil-hydraulic tool, for example an excavator tool, demolition shear, a forestry tool, or a civil engineering tool. With these tools and their typical application areas, there is a particularly high risk of a line break due to damage during operation. The emergency stop function described above is particularly advantageous when the frame is self-propelled.

[0010] The hydraulic cylinder can be single-acting or double-acting. The volume control valve can be a 4 / 3-way proportional valve. It preferably has four ports. In a double-acting hydraulic cylinder, a first port is connected to a first working line, which is connected to a first chamber of the hydraulic cylinder. A second port is connected to a second working line, which is connected to the second chamber of the hydraulic cylinder. The third port is connected to a pressure line leading from the hydraulic pump, and the fourth port is connected to a tank line leading to the tank. A (primary) pressure relief valve can be provided between the tank line and the pressure line.

[0011] It is advantageous if a pressure relief valve arranged parallel to the suction device is arranged in the bypass, or if the suction device has a (secondary) pressure relief function.

[0012] In an advantageous embodiment, the bypass has a branch from a tank line, and the supply line is the tank line. Hydraulic oil can thus flow from the tank into the working line via the bypass.

[0013] An advantageous location for an emergency stop device is in the bypass between a branch from the working line (in which the suction device is located) and a branch connected to a line in which the pressure relief valve is located. The pressure relief valve then remains active even when the bypass is closed in the event of a leak, protecting the mobile machine from damage. A location between the suction device and the branch connected to the line in which the pressure relief valve is located is particularly preferred.

[0014] Preferably, the emergency stop device or the suction device equipped with an emergency stop function is designed to switch back and forth between a blocking state and a release state.

[0015] It is conceivable that the suction device equipped with an emergency stop function includes a check valve that can be closed manually, electrically, hydraulically and / or pneumatically.

[0016] Preferably, a control unit controls the volume control valve and the control unit is also connected to the emergency stop device and / or the suction device in order to control the emergency stop device and / or the suction device to close the line when a leak is detected in the working line.

[0017] The hydraulic system may include a pressure sensor and / or a hydraulic circuit for detecting a leak in the working line. It is also possible for the leak to be detected by, or only by, an operator of the mobile work machine, and for a signal to be transmitted to the control unit by activating an emergency stop (emergency stop switch / operating unit). Preferably, an emergency stop device is arranged in a driver's cab of the mobile hydraulic machine. If the driver of the mobile hydraulic (construction) machine detects a leak, he or she can activate the emergency stop device and thus prevent the hydraulic oil from escaping further at the point of failure.

[0018] In a preferred embodiment, the mobile work machine is a hydraulic construction machine, in particular 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.

[0019] Furthermore, the use of a valve or a shut-off device is provided in order to, in a mobile work machine comprising

[0020] - a substructure,

[0021] - a superstructure and

[0022] - a boom assembly, and

[0023] - a hydraulic system comprising a hydraulic pump, a working line, a hydraulic consumer, a volume control valve which is designed to be able to regulate an oil flow in the working line connected to the consumer in order to control the consumer, and a bypass which can bridge the volume control valve, wherein a suction device with a make-up function is arranged in the bypass in such a way that when the working line carries excess pressure, the bypass is closed and when the working line carries low pressure, the bypass is open and the working line or the hydraulic consumer connected to the working line can suck in or make up or refill hydraulic oil via a supply line, in the event that a leak is detected in the working line, the line in the bypass or the supply line is to be shut off and a volume flow of hydraulic oil in the direction of the working line is to be blocked.

[0024] The hydraulic system can be designed as described above.

[0025] Furthermore, a method for minimizing hydraulic oil loss in a mobile work machine as described above in the event of a leak in a working line is provided, comprising the following steps:

[0026] If a leak occurs in the working line, a. moving and / or holding the at least one volume control valve in a blocking position and thereby blocking the working line to the pressure line connected to the hydraulic pump, and b. blocking the bypass or the supply line and thereby preventing hydraulic oil from entering the working line via the bypass.

[0027] Steps a. and b. can be performed approximately simultaneously or sequentially. The method is particularly reliable and easy to control in an emergency. The mobile work machine can be configured as described above.

[0028] Preferably, the method comprises the following further step: c. After eliminating the leak, releasing the volume control valve and opening the bypass or the supply line so that hydraulic oil can flow into the working line via the bypass when low pressure prevails in the working line.

[0029] This has the advantage that the original leak-free state can be restored, particularly without the need for tools and / or without having to replace cartridges, for example. The emergency stop function can be deactivated, for example, after the leak has been rectified by pressing the emergency switch again. However, it is also possible for the valves or shut-off devices to be automatically controlled by a sensor that detects a pressure drop, or for the valves or shut-off devices to close hydraulically fully automatically in the event of a pressure drop. The method preferably comprises the following further step after steps a. and b. have been performed:

[0030] - Blocking a second bypass, which can bypass the volume control valve, wherein a replenishment device with a replenishment function is arranged in the second bypass, such that when a second working line assigned to the hydraulic consumer carries overpressure, the second bypass is closed and when the second working line carries low pressure, the second bypass is opened and the second working line or the hydraulic consumer connected to the second working line can replenish hydraulic oil via the supply line, or

[0031] - Shutting off the supply line, whereby the shut-off is also carried out when the second working line is leak-free in order to prevent hydraulic oil from escaping from the first working line.

[0032] It is conceivable to shut off the supply line in such a way that both bypasses cannot replenish or refill. The volume control valve preferably assumes a state in which both working lines are switched off and the pressure line is connected to the tank line. The hydraulic cylinder is preferably double-acting, with one working line connected to each chamber.

[0033] It is also conceivable to design the emergency stop devices and / or the suction devices equipped with an emergency stop function in such a way that the two components assigned to a single hydraulic consumer are hydraulically and / or electrically connected to one another, so that in the event of a leak, both bypasses can be shut off particularly easily.

[0034] Two preferred embodiments of the invention are explained in more detail below with reference to the drawings. Identical or functionally identical components are provided with the same reference numerals in the figures. The figures show:

[0035] Figure 1 : a simplified schematic representation of an embodiment of a hydraulic system of a mobile

[0036] Working machine with hydraulic cylinder,

[0037] Figure 2: a further schematic simplified representation of an embodiment of a hydraulic system of a mobile work machine with additional emergency stop device, as well as

[0038] Figure 3: a representation of an excavator.

[0039] Figures 1 and 2 show a hydraulic control circuit 1 of a mobile work machine. A pump 3, driven by a motor 2, pumps hydraulic oil into a pressure line 4 to control a double-acting hydraulic cylinder 5. A control section 6 of the hydraulic control circuit is shown in simplified form. For the hydraulic control of the hydraulic cylinder 5, a volume control valve 7 is provided, which is designed as a 4 / 3-way valve, in particular as a 4 / 3-way proportional valve, as shown. It has four ports A, B, P, T. A first port A is connected to a first working line 8, which is connected to a first chamber 9 of the hydraulic cylinder 5. A second port B is connected to a second working line 10, which is connected to the second chamber 11 of the hydraulic cylinder 5.The third port P is connected to the pressure line 4 and the fourth port T is connected to a tank line 12 (also called return line) leading to the tank 13.

[0040] In a first extreme state of the volume control valve 7, the first port A is connected to port P and the pressure line 4, while the second port B is connected to the fourth port T. In this case, hydraulic medium can flow from the pressure line 4 into the first chamber 9 of the hydraulic cylinder 5, while the second chamber 11 is connected to the tank 13 via ports B, T. In this way, a piston 14 of the hydraulic cylinder 5 is moved in a first direction. In the illustrated neutral position (second extreme state) of the volume control valve 7, ports A and B are blind-switched, i.e. closed, and the pressure line 4 is connected to the tank line 12. The piston 14 of the hydraulic cylinder 5 then remains in its current position because there is no outflow or inflow. A blocking state prevails.In the third extreme state of the volume control valve 7, port P is connected to port B and port A is connected to port T. In this case, hydraulic fluid flows from the pressure line 4 into the second chamber 11 of the cylinder 5, and the first chamber 9 is connected to the tank 13 via port A and port T. The hydraulic fluid then exerts a force on the piston 14 of the hydraulic cylinder 5 such that it is displaced in a second direction opposite to the first direction. As already described, the volume control valve 7 is designed as a proportional valve. The hydraulic fluid flow coming from the pressure line 4 is distributed between the chambers 9, 11 by varying the valve states between the three extreme states, making it possible to bring about a defined speed of the piston movement by controlling / regulating the volume flow.

[0041] Behind the outlet of the pump 3 and in front of the volume control valve 7, a branch 15 is provided in the pressure line 4, from which a line 16 branches off, which leads to the tank 13 via a pressure relief valve 17 opening in the direction of the tank 13.

[0042] The tank line 12 leads to the tank via a return filter 18. Instead of the return filter shown, it is also conceivable to use a different filter with, for example, a different filter medium. The return filter 18 can be bypassed by a bypass 19 with a differential pressure valve 19 opening towards the tank 13. The return filter overcoming pressure lies in a range between 0.5 and 1.5 bar. Between the return filter 18 and the branch to the pressure relief valve 17, an optional spring-loaded check valve (shown here) is provided. This opens towards the tank 13 and generates a back pressure in a range of 3-8 bar, preferably approximately 5 bar.

[0043] The volume control valve 7 has two bypasses 20, 21. A first bypass 20 branches off from the tank line 12 between port T and the branch with the pressure relief valve 17 and ends in a branch 22 of the first working line 8. A check valve 23 is arranged in the first bypass 20. Parallel to the check valve 23, the bypass 20 has a secondary pressure relief valve 24. The secondary pressure relief valve 24 is located in a line that branches off from the first working line 8 between port A and the branch 22 of the first bypass 20 and ends in a branch 25 in the first bypass 20 between the check valve 23 and the branch of the tank line. The check valve 23 functions as a so-called make-up or suction valve, which is connected to the tank 13. When the first working line 8 carries excess pressure, the check valve 23 closes.However, if the first working line 8 carries low pressure (in the illustrated embodiment, compared to the back pressure of the spring-loaded check valve or preload valve), the anti-cavitation valve opens and the first working line 8 or the first chamber 9 can replenish from the tank line 12 or the tank 13, respectively, thus preventing cavitation. If there is insufficient volume flow to supply the hydraulic cylinder, trouble-free operation is still possible thanks to the anti-cavitation valve.

[0044] The second bypass 21 of the volume control valve is constructed analogously to the first bypass 20 and protects the second working line 10 or second chamber 11 against both overload and cavitation. The bypass line 26 of the second bypass 21 is connected to the tank line 12 on the tank side in a branch 27 located between the branch to the pressure relief valve 17 and the branch to the first bypass.

[0045] It can also be provided that the anti-cavitation valve is generally connected to a return line (e.g., directly to the tank) of an open hydraulic circuit. The anti-cavitation valve and the secondary pressure relief valve can be combined in a single cartridge. The pressure relief function and the make-up function can be integrated into one valve, thus making it compact.

[0046] To control the volume control valve 7, an operating unit 28 designed as a joystick can be connected to a control unit 29. The latter, in turn, is connected to the volume control valve 7 via signal lines 30 and 31. The two working lines 8, 10 can be designed in the form of ducts, pressure medium pipes, or flexible hoses. Flexible hoses are indispensable for movable hydraulic cylinders. If, during operation, as described in more detail above, a flexible hose gets caught on a protruding rebar, for example, during the demolition of a building, and thereby breaks, a large amount of hydraulic oil would escape from the break point in conventional hydraulic systems.

[0047] In the event that the return oil flows through the return filter 18 at the return filter overcoming pressure before reaching the tank 13, the filter back pressure always acts on the anti-cavitation valves 23, opening them in the event of a leak in the associated working line, where oil is then immediately forced out (due to the previously mentioned filter back pressure). If the optional spring-loaded check valve (generally preload valve) is also present, the oil leakage from a defect in the aforementioned working line would be further exacerbated. In this case, in the event of a leak, oil would not be sucked in from the tank via the anti-cavitation valves, but even a small standby flow rate (3-10 l / min.) of a running control pump or a fixed displacement pump that is not boosted by control commands creates a preload pressure in the bypass circuit (anti-cavitation circuit) and causes oil to leak.If a non-defective hydraulic circuit is now activated, the pump can increase its flow rate to its maximum, depending on the activation intensity. The return oil from the activated function then escapes from the described defect in the working line, opening the suction valves instead of taking the intended route via the preload valve through the return filter into the tank.

[0048] To prevent this, the invention provides an emergency stop device or an emergency stop function which, in the event of an emergency, prevents hydraulic oil from flowing towards the rupture point in the affected working line and also prevents hydraulic oil from reaching the rupture point from the bypass bridging the volume control valve and escaping from the leak in the working line. Figure 1 shows a first embodiment of an emergency stop device. The check valve 23 is designed as a controllable valve. The check valve 23 must be designed such that, in the event of a hose rupture, it is moved from an open position to a closed position, regardless of whether an opening pressure is applied. The closing element can be moved into the closed position hydraulically, mechanically, electrically, or pneumatically.

[0049] If the make-up function is not implemented by means of a check valve, the invention provides that the valve or the valve arrangement implementing the make-up function is controlled, actuated or moved accordingly in the event of damage in order to prevent a flow of hydraulic oil through the bypass to the damaged working line.

[0050] In addition, in such an emergency, it must be ensured that the damaged working line between the break point and pressure line 4 is shut off or blocked. This is already the case if an operator of the mobile work machine no longer operates the control unit 28 for controlling the hydraulic cylinder. The operator can be instructed to do so. To ensure that the shutoff of the damaged working line remains in place even if the control unit is operated, the control unit can be instructed not to forward the operation to the volume control valve. The control unit can also be locked, for example. It is also conceivable to prevent the control of the volume control valve or a change in state in another way. It is also conceivable that in an emergency, the volume control valve is automatically transferred to a state in which the damaged working line is blocked.It is also conceivable to connect the working line by means of an additional valve or

[0051] valve arrangement or a shut-off device that is controlled, actuated or moved accordingly in an emergency.

[0052] Figure 2 shows a second embodiment of an emergency stop device 32 with two different installation positions. Only one of the installation positions is assumed at a time. In the first installation position, the emergency stop device 32 is located in the bypass 20, 21 between the branch 25 to the secondary pressure relief valve 24 and the check valve 23. In an emergency, the emergency stop device 32 blocks the flow of hydraulic oil via the tank line 12 to the damaged working line. The emergency stop device 32 can be an additional valve, a valve arrangement, or a shut-off device such as a slide valve, ball valve, or the like. A 2 / 2-way valve is shown as the emergency stop device 32, which is held in the open position in the neutral position (rest position) by a spring. It is an electrically or electronically controlled solenoid valve that can be controlled by the control unit 29.In an emergency, the control unit can move the 2 / 2-way valve to a closed position and shut off the bypass 20, 21 connected to the tank line 12, preventing refilling. Due to its position, the pressure relief function remains active even when the line is shut off by the emergency stop device 32.

[0053] In the second installation position, the emergency stop device 32 is located in the bypass 20, 21 between the branch from the tank line 12 and the branch 25 to the secondary pressure relief valve 24. If the make-up function and pressure relief function are implemented together in a common device, the emergency stop device can be located in the bypass on one or the other side of the device. In general, it is also conceivable for the emergency stop device to be located anywhere in the bypass, regardless of how the make-up function and pressure relief function are technically implemented. It is also conceivable for the emergency stop device to be located outside the bypass, specifically in the tank line between the branch to the bypass and the return filter, in particular between the branch to the bypass and the branch to the pressure relief valve, since the pressure relief function is then still present.If the emergency stop device is located between the branch to the bypass near the filter and the branch to the pressure relief valve, the emergency stop device can shut off the refilling of both suction valves and the flow of hydraulic oil into both bypasses. This design can be particularly cost-effective. In this case, both bypass lines preferably have a single (common) connection to the tank line, and the connection of the volume control valve to the tank line is located between the emergency stop device and the filter, with the branch of the pressure relief valve located in the line from the volume control valve to the tank. The junction point of the two bypass lines is on the side of the connection of the volume control valve to the tank line, far from the filter. This ensures that the emergency stop device only shuts off the control section affected by a leak, while the other functions or control sections remain available.

[0054] Preferably, the first bypass and the second bypass, as well as the associated emergency stop devices, are functionally identical. If an emergency stop function is provided for each bypass, they can be designed identically. However, it is also conceivable, due to space constraints or other design limitations, to design the emergency stop devices or check valves with emergency stop functions differently.

[0055] In general, it is also conceivable to use emergency stop devices or check valves with an emergency stop function that automatically close in the event of a leak in the working line and a resulting pressure drop. A sensor could also be considered that detects such a pressure drop and reports it to the control unit, which then decides whether an emergency exists and whether appropriate measures need to be taken. It may also be useful for the operator of the mobile machine to inspect a damage incident, for example, using the emergency stop button, and forward the information to the control unit, which then executes the appropriate measures.

[0056] In addition, it may be useful that if the emergency stop devices or check valves with emergency stop function of a bypass close the bypass line in the event of an emergency, this also happens automatically for the other bypass of the same hydraulic cylinder.

[0057] Particularly preferably, it can be provided that the emergency stop devices or check valves with emergency stop function can be returned to a neutral state without great effort. This can be done, for example, by a shut-off device releasing the line again or by a valve or valve arrangement being returned to the neutral position without the need to replace components.

[0058] Figure 3 shows a mobile work machine 33 in a preferred embodiment as an excavator, in particular a long-arm boom excavator with a substructure 34 that is connected to a superstructure 36 via a slewing mechanism 35 that can rotate about a slewing axis S. With the help of the slewing mechanism 35, a controlled slewing movement between the superstructure 36 and the substructure 34 about the slewing axis S is possible. In general, a distinction can be made between mobile excavators and crawler excavators. The substructure 34 can, on the one hand, have tires in a chassis, and this is referred to as a mobile excavator, although mobile excavators are only used in the weight class up to 25 t, and, on the other hand, have tracks, so that the term crawler excavators is 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 is designed as a crawler excavator, which falls within a weight class typical for demolition work, between 25 t and 400 t. The superstructure 36 has a driver's cab 37 at its end facing the direction of travel F (straight-ahead alignment) and a counterweight 38 opposite the driver's cab 37. Figure 3 shows a three-link boom assembly 39, which is attached to the superstructure 36 next to or behind the driver's cab 37. The boom assembly 39 has three consecutive links 40, 41, 42: a first link 40, called the boom, a second link 41, called the intermediate boom, and a third link furthest from the superstructure, which is called the stick 42, with two consecutive links being pivotably mounted to one another by means of bolts.The boom assembly 39 further comprises a boom cylinder 43, which can move the first link 40, and an intermediate boom cylinder 44, which can move the second link 41 of the boom assembly 39. Furthermore, a stick cylinder 45 is provided, which can be driven to move the stick 42. An attachment 47 is attached to the free end of the stick 42, through which a stick head pin 46 passes. This connection can preferably be established by a quick coupler. The attachment 47 and the quick coupler can also be pivoted about the pivot axis defined by the stick head pin 46. In this embodiment, the attachment 47 is a gripping tool; however, any hydraulic attachments, such as shears, can be used.

[0059] The mobile hydraulic construction machine comprises a hydraulic system that, among other things, drives the boom cylinder 43 and the intermediate boom cylinder 44, as well as the stick cylinder 45 and optionally a hydraulic cylinder of an attachment 42, using hydraulic oil. At least one valve block 48, a hydraulic oil tank 49, and a hydraulic pump 50 are associated with the hydraulic system and are located in the superstructure 36 (also called the uppercarriage). The hydraulic pump 50 delivers the hydraulic oil of the hydraulic system and is connected to the at least one valve block 48 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 at least one valve block 48 controls and regulates a hydraulic oil flow to the aforementioned hydraulic cylinders.Starting from at least one valve block 48, the working lines 51 lead to the hydraulic cylinders.

[0060] Figure 3 shows the hydraulic system in the simplest possible schematic. For example, only one working line 51 is shown, but depending on the attachment used and the type of construction machine, there can be several, but at least two, hydraulic lines 51 per hydraulic cylinder. The type of attachment 47 and the movement it can perform define the number of (used and connected) hydraulic lines. For example, the attachment can have hydraulic cylinders to perform movements, such as opening and closing, or a hydraulic cylinder can be provided to move the attachment relative to the boom, e.g. the bucket cylinder. The hydraulic cylinders can be single-acting or double-acting.

[0061] Depending on where they are located and where they lead, the hydraulic lines are formed by channels that are firmly attached to the top of the boom assembly or by flexible hose lines. In areas where movement must be permitted, the hose lines are arranged in a curved shape. These areas are called flexible hose bends 52 and differ from hose bends that are purchased as components and have a fixed, rigid geometry. The flexible hose bends 52 allow the individual links of the boom assembly 39 to pivot relative to one another without the hydraulic lines 51 being interrupted or ruptured.

[0062] The previously described control section with emergency stop device or emergency stop function can be used in the previously described hydraulic system of the mobile work machine. The emergency stop device can be used for one working cylinder, for example that of the attachment, stick, boom, etc., or for several of the working cylinders, or even for all working cylinders, to protect against the leakage of large quantities of hydraulic oil in the event of a hose rupture. This makes it particularly easy and safe to prevent large quantities of hydraulic oil from escaping and causing damage in the event of a leak in the working line. Furthermore, the other functions of the mobile work machine are retained, and the work machine can be moved, for example, to repair the leak.This is particularly advantageous if the leak is located far away from the superstructure, for example in the area of ​​the boom group, especially the stick or bucket, and these are not accessible to an operator when the leak occurs.

Claims

Patent claims 1. Mobile work machine (33) having a substructure (34), a superstructure (36) and a boom assembly (39), and a hydraulic system comprising a hydraulic pump (3), a working line (8, 10), a hydraulic consumer (5), a volume control valve (7) which is designed to be able to regulate an oil flow in the working line (8, 10) connected to the consumer (5) in order to control the consumer (5), and a bypass (20, 21) which can bridge the volume control valve (7), wherein a refill device (23) with a refill function is arranged in the bypass (20, 21) in such a way that when the working line (8) carries excess pressure, the bypass (20) is closed and when the working line (8) carries low pressure, the bypass (20) is opened and the working line (8) orthe hydraulic consumer (5) connected to the working line (8) can replenish hydraulic oil via a supply line (12), characterized in that the replenishment device (23) has an emergency stop function or that the hydraulic system comprises an emergency stop device (32) which is designed to close the line in the bypass (20) or the supply line (12) when a leak is detected in the working line (8).

2. Mobile work machine according to claim 1, characterized in that the hydraulic consumer (5) is a hydraulic cylinder which causes a movement of the boom assembly (39) and / or an oil-hydraulic attachment (47).

3. Mobile work machine according to claim 1 or 2, characterized in that a pressure relief valve (24) arranged parallel to the suction device (23) is arranged in the bypass (20), or the suction device has a pressure relief function.

4. Mobile work machine according to one of the preceding claims, characterized in that the bypass (20) is a branch of a tank line and the supply line (12) is the tank line.

5. Mobile work machine according to claim 3 or 4, characterized in that an emergency stop device (32) is located in the bypass (20, 21) between a branch (22) from the working line (8) and a branch (25) which is connected to a line in which the pressure relief valve (24) is arranged.

6. Mobile work machine according to one of the preceding claims, characterized in that the emergency stop device (32) or the suction device (23) equipped with an emergency stop function is designed to switch back and forth between a blocking state and a release state.

7. Mobile work machine according to one of the preceding claims, characterized in that the suction device (23) equipped with an emergency stop function comprises a check valve that can be closed manually, electrically, hydraulically and / or pneumatically.

8. Mobile work machine according to one of the preceding claims, characterized in that a control unit (29) controls the volume control valve (7) and the control unit (29) is also connected to the emergency stop device (32) and / or the suction device (23) in order to control the emergency stop device (32) and / or the suction device (23) to close the line when a leak is detected in the working line (8).

9. Mobile work machine according to one of the preceding claims, characterized in that the hydraulic system comprises a pressure sensor and / or a hydraulic circuit for detecting a leak in the working line (8).

10. Use of a valve or a shut-off device for a mobile work machine (33) having a base (34), a superstructure (36) and - a boom assembly (39), and - a hydraulic system comprising a hydraulic pump (3), a working line (8, 10), a hydraulic consumer (5), a volume control valve (7) which is designed to be able to regulate an oil flow in the working line (8, 10) connected to the consumer (5) in order to control the consumer (5), and a bypass (20) which can bridge the volume control valve (7), wherein a re-suction device (23) with a re-feed function is arranged in the bypass (20) in such a way that when the working line (8) carries excess pressure, the bypass (20) is closed and when the working line (8) carries low pressure, the bypass (20) is open and the working line (8) orthe hydraulic consumer (5) connected to the working line (8) can suck in hydraulic oil via a supply line (12), in the event that a leak is detected in the working line (8), the line in the bypass (20) or the supply line (12) is to be shut off and thereby a volume flow of hydraulic oil in the direction of the working line (8) is to be blocked.

11. A method for minimizing hydraulic oil loss in a mobile work machine (33) in the event of a leak in a working line (8) according to one of the preceding claims 1 to 9, comprising the following steps: If a leak occurs in the working line (8), a. Moving and / or holding the at least one volume control valve (7) in a blocking position and thereby blocking the working line (8) to the pressure line (4) connected to the hydraulic pump (3), and b. Shutting off the bypass (20) or the supply line (12) and thereby preventing hydraulic oil from entering the working line (8) via the bypass (20).

12. The method according to claim 11, characterized in that the method comprises the following further step: c. After eliminating the leak, releasing the volume control valve (7) and opening the bypass (20) or the supply line (12) so that hydraulic oil can flow into the working line (8) via the bypass (20) when low pressure prevails in the working line (8).

13. Method according to claim 11 or 12, characterized in that the method comprises the following further step after steps a. and b. have been carried out: - blocking a second bypass (21) which can bypass the volume control valve (7), wherein a replenishment device with a replenishment function is arranged in the second bypass (21), such that when a second working line (10) associated with the hydraulic consumer (5) carries excess pressure, the second bypass (21) is closed and when the second working line (10) carries low pressure, the second bypass (21) is opened and the second working line (10) or the hydraulic consumer (5) connected to the second working line (10) can replenish hydraulic oil via the supply line (12), or - Shutting off the supply line (12), wherein the shutting off is also carried out when the second working line (10) is leak-free in order to prevent hydraulic oil from escaping from the first working line (8).

Images