DE102018218165A1 - Arrangement for a working hydraulics, method and working hydraulics - Google Patents

Abstract

The invention discloses an arrangement for working hydraulics, which has two hydraulic consumers, which are arranged fluidically in parallel. To supply the consumer, the arrangement has at least one hydraulic machine, a respective control valve for controlling the respective consumer being provided fluidly between the hydraulic machine and the respective consumer. A pressure limiting valve is connected to at least one pressure side of a first consumer, which opens a pressure medium connection to a tank from a certain safety pressure. Furthermore, a control is provided in the arrangement, which can control the control valves and the hydraulic machine. This controller is configured in such a way that it recognizes at least one operating state in which the pressure on the pressure side of the first consumer would reach or exceed the safety pressure due to activation of the consumers and / or due to load states of the consumers. If this occurs, the control avoids at least one operating state by means of control measures at least one of the control valves or more of the control valves or more of the control valves and / or the hydraulic machine.

Description

Field of the Invention

The invention relates to an arrangement for working hydraulics according to the preamble of claim 1. Furthermore, the invention relates to a method and a working machine.

Background of the Invention

Working hydraulics are known from the prior art, which have several consumers, for example hydraulic cylinders and / or hydraulic motors. The consumers can be supplied by a hydraulic pump, e.g. can be powered by an internal combustion engine. A consumer can be, for example, a hydraulic cylinder to which a control valve is assigned which controls the supply to the hydraulic cylinder and thus the movement of a piston which separates a pressure chamber of the hydraulic cylinder from another pressure chamber of the hydraulic cylinder. The hydraulic cylinder can be installed in an excavator, for example, and can be designed to lift a load. In order to protect the system from damage, for example due to excessive load, a pressure relief valve can be arranged between the control valve and a pressure chamber of the hydraulic cylinder, which opens a pressure medium connection to a tank when the pressure in the hydraulic cylinder is too high. However, it is possible that the excavator wants to lower a load, for example, and for this purpose a pressure medium connection is established between a pressure chamber in the hydraulic cylinder and the hydraulic pump in order to release pressure medium from the pressure chamber. At the same time, for example, a further consumer can be activated, ie a pressure medium connection of the further consumer is opened to the hydraulic pump. It has been shown that in this state the pressure limiting valve opens a pressure medium connection to the tank unintentionally under certain load conditions. The consequence of this is that the hydraulic cylinder under load sinks in an uncontrolled manner and thus a lowering of the load cannot be controlled.

Disclosure of the invention

In contrast, the object of the invention is to provide a device-technically simple and inexpensive arrangement for working hydraulics which can be checked and controlled at any time. A further object is to create a method with this arrangement with which the arrangement for working hydraulics can be controlled in a controllable manner at all times and, in addition, working hydraulics with this arrangement are to be created.

The object according to the arrangement for working hydraulics is achieved according to the features of claim 1. The task with regard to the method is achieved according to the features of claim 14 and with regard to working hydraulics according to the features of claim 15.

Advantageous developments of the invention are the subject of the dependent claims.

According to the invention, an arrangement for working hydraulics is provided which has at least one consumer. The consumer can be, for example, a hydraulic cylinder which is intended to lift a load, for example the hydraulic cylinder can move a boom of an excavator. Furthermore, the arrangement has a further hydraulic consumer, which is arranged in particular fluidically parallel to the first consumer. The first consumer and the further consumer are supplied with pressure medium by at least one hydraulic machine, past which a respective control valve, for example a 4/3-way control valve, is provided for controlling the respective consumer between the hydraulic machine and the respective consumer. It is conceivable that, apart from the control valves, there are no further hydraulic elements that influence the pressure medium flow. On a pressure side of the first consumer, that is to say in particular between the first consumer and the control valve of the first consumer, a pressure limiting valve is connected, which has the task of opening a pressure medium connection to a tank from a certain safety pressure on the pressure side. In other words, the arrangement has a pressure protection on the secondary side.

This can be used for component protection, for example, since damage to the working hydraulics can occur from a certain pressure on the pressure side. The arrangement also has a controller that controls in particular the control valves of the various consumers and / or the hydraulic machine, for example the delivery rate of the hydraulic machine. The controller is also configured to recognize and / or anticipate critical operating states at which the pressure on the pressure side, to which a pressure relief valve is connected, reaches the safety pressure at which the pressure relief valve opens due to activation of the consumers and / or the hydraulic machine would be or would be exceeded. If the control system recognizes that a critical operating state is present, it initiates control measures which relate to at least one control valve or more of the control valves and / or the hydraulic machine in order to avert or prevent the critical state.

An advantage of this invention is that the arrangement ensures that the consumer, in particular the first consumer, which has a pressure side to which a pressure relief valve is connected, can be controlled at all times and can be safely controlled by the controller. In other words, for example, in particular if the consumer is configured to lift a heavy load, the load can be lowered in a controlled manner without the pressure limiting valve establishing a pressure medium connection to the tank, since the pressure on the pressure side exceeds the safety pressure. Furthermore, the arrangement increases the safety for people who are in the working area of a working machine which is equipped with the working hydraulics with this arrangement. Furthermore, the arrangement automatically recognizes a critical operating state through the control, in which the pressure relief valve could open, i.e. a person who operates the working hydraulics does not have to recognize or predict the critical operating state, and thus incorrect operation and human error are less probably.

The critical operating state arises especially when the first consumer is a hydraulic cylinder. Furthermore, the critical operating state occurs in particular when the first hydraulic cylinder lifts a, in particular heavy, load, that is to say that there is already a relatively high pressure on the pressure side to which the pressure relief valve is connected, and the load is slowly released. The pressure sides of a hydraulic cylinder can also be pressure spaces. That is to say, in particular, a first control valve opens a pressure medium connection from a pressure chamber, to which the pressure limiting valve is connected, to a tank and a further pressure medium connection from the further pressure chamber of the hydraulic cylinder to the hydraulic machine. In other words, a pressure chamber of the first hydraulic cylinder is charged with pressure medium and at the same time pressure medium is released from another pressure chamber of the hydraulic cylinder to the tank so that a piston rod of the hydraulic cylinder can retract. Now, in the case of a further consumer, which in particular is also a hydraulic cylinder, a pressure medium connection from a pressure chamber of the further consumer to the hydraulic machine can also be opened. If the pressure in the pressure chamber of the further consumer, which now has a pressure medium connection to the pressure chamber of the first hydraulic cylinder, is high, it can happen that the pressure rises in the pressure chamber to which the pressure limiting valve is connected. In other words, the lowering of the load and the simultaneous opening of a pressure medium connection from another consumer to the hydraulic machine can lead to the critical operating state occurring. If the pressure relief valve is opened in this state, i.e. there is a rapid drop in pressure in the pressure chamber, it can happen that the load that the hydraulic cylinder holds and / or lowers falls down in an uncontrolled manner.

Preferably, at least one pressure sensor is provided in the arrangement of the working hydraulics, which measures a pressure, in particular on the pressure side of the first consumer, to which the pressure relief valve is connected, and forwards it to the controller, so that the controller can detect an operating state of the working hydraulics. In other words, a pressure sensor is connected between the pressure side of the consumer and the control valve. This determines the pressure on the printed page and can report this pressure to the controller. The pressure sensor can only report a critical pressure to the controller. For example, the pressure sensor can be configured so that it only reports the pressure to the control when it is, for example, 10 bar below the safety pressure at which the pressure relief valve opens, or the pressure sensor can, in particular, at short intervals during operation of the control system's working hydraulics continuously, report the printing of the printed page. The control can better detect and / or predict the critical operating state by means of the pressure sensor. The critical operating state does not always occur when the consumer lowers a load and another consumer opens a pressure medium connection to the hydraulic machine, but it is also possible for the consumer to lower a smaller and / or less heavy load and thus the pressure on the pressure side less, that is, the pressure relief valve does not trip, although another consumer has a pressure medium connection to the hydraulic machine. The pressure sensor enables a more precise prediction of the critical operating state.

The respective control valves or the control valve, that is to say the control valve of the first consumer or of the further consumer, is / are preferably electronically controllable. In other words, the control valves or the control valve can be controlled, in particular, electromechanically and / or electrohydraulically. The electromechanical control of the control valve or the control valves can be implemented, for example, by using electromagnets. The control can influence the control valves or the control valve by means of the electronically controllable control valves or the electronically controllable control valve. It is also possible for the respective control valves to be hydraulically adjustable. For example, pressure reducing valves can be used for this.

The consumers are preferably designed such that they each have two Have work connections. Depending on the switching position of the respective control valve, the working connections of the respective consumer preferably establish a pressure medium connection of the respective pressure sides to the tank and / or the hydraulic machine. In other words, a consumer has at least two pressure sides, which in the case of a hydraulic cylinder can be pressure spaces, for example, which have a respective working connection.

The control valve of the respective consumer can each have a valve slide. Furthermore, the respective valve slide can preferably have at least three different switching positions. In a first spring-centered switching position, which is a basic position, the working connections can preferably be closed, that is to say the pressure sides have no pressure medium connection to, for example, the tank and / or the hydraulic machine. A further switching position or further switching positions of the valve slide can connect a first pressure side of the assigned consumer to the tank and the second pressure side of the consumer to the hydraulic machine. Conversely, a third or third switching position (s) can connect the first pressure side of the assigned consumer to the hydraulic machine and the second pressure side to the tank. If the valve slide is continuously adjustable, several switching positions can be provided, in which the respective pressure sides have a pressure medium connection to the tank or the hydraulic machine. In the further switching position (s), the valve spool is shifted from the basic position in a first direction. In the third switching position (s), the valve spool is moved in the opposite direction to the first direction, starting from the basic position.

In particular, the critical operating state occurs when the additional consumer is also a hydraulic cylinder. Using an excavator as an example, the first hydraulic cylinder is, for example, the boom cylinder and the second hydraulic cylinder is, for example, a stick cylinder. In this example, the critical operating state can arise when the extension cylinder lowers a large load and, at the same time, a correction movement can take place with the stick cylinder, for example to compensate for a fluctuation.

Preferably, at least the first hydraulic cylinder or, if there are further hydraulic cylinders on the working hydraulics, part of the hydraulic cylinders or all hydraulic cylinders have a piston. The piston of a respective hydraulic cylinder can separate two pressure chambers. A piston rod, which protrudes from the hydraulic cylinder, can be arranged on the piston. The piston rod can be moved out of the hydraulic cylinder or retracted into it by the movement of the piston. If the hydraulic cylinder is a differential cylinder, it has in particular two pressure spaces, one of which is penetrated by the piston rod. Using the example of the extension cylinder, the hydraulic cylinder can be fastened to the excavator main body and the piston rod can be moved to the boom, for example, and the boom can be moved by moving the piston rod with the piston in the hydraulic cylinder. For this purpose, a pressure chamber on one side of the piston is charged with pressure medium and pressure medium is released from the further pressure chamber, so that the piston rod either moves out of the hydraulic cylinder or the piston rod moves into it.

A control measure of the control in order to avert the critical operating state can be to throttle the first consumer, which is for example the hydraulic cylinder, and / or one of the other consumers and / or to block a pressure medium connection between the hydraulic machine and one of the consumers. In other words, if the critical operating state occurs, individual operation, that is to say the opening of only one of the control valves, can be initiated by the control. The controller can, for example, initiate the control measure if the pressure on the pressure side to which the pressure relief valve is connected is below a certain amount, for example 10%, below the safety pressure. Another possibility is that the control unit initiates the control measure when the critical operating state has been reached, that is to say when the pressure limiting valve opens briefly in order to release pressure medium from the pressure side. By initiating the control measure, control over the first consumer, to whose pressure side a pressure relief valve is connected, can be regained. In order to avert the critical operating state, a control valve is therefore closed, that is to say either the control valve of the first consumer is interrupted and / or the control valve of another consumer. Another possibility is, as described above, instead of disconnecting the pressure medium connection, to throttle the pressure medium connection, in particular as a function of the activation of the first consumer and / or as a function of the pressure prevailing in the pressure chamber. In other words, it may not be necessary, for example, to completely disconnect a pressure medium connection if, for example, by activating the first consumer, the pressure on the pressure side to which a pressure relief valve is connected is reduced. If the first consumer is, for example, a hydraulic cylinder and this lowers a load, the pressure medium connection of a further consumer can only be throttled if the load is released at least at a certain minimum speed and thereby Pressure medium is released from a pressure chamber of the hydraulic cylinder.

The arrangement can preferably have a pressure sensor, in particular a further one, which is connected on the output side of a pressure connection of the hydraulic machine, in particular between the pressure connection of the hydraulic machine and the respective control valves of the consumers. The pressure detected by the pressure sensor is also communicated to the control. The pressure sensor at the pressure connection of the hydraulic machine is known to the control by the pressure sensor and thus the control can preferably control the hydraulic machine. This means that the controller can, for example, set a volume flow that conveys the hydraulic machine, depending on the pressure on the outlet side of the pressure connection of the hydraulic machine. Alternatively or additionally, the hydraulic machine can furthermore have a pressure and / or a pressure delivery flow controller with or without the possibility of overriding the setpoint value of the pump, and / or a delivery flow controller with suitable dynamics. Furthermore, it is additionally or alternatively possible to adjust the barometric or volumetric supply to the actuating chamber of the hydraulic machine.

If the hydraulic machine is electronically controlled, it is possible that the control, in order to avert the critical operating state, controls the hydraulic machine in such a way that the pressure is limited. In other words, the delivery rate of the hydraulic machine can be limited, for example, if the control valve of the first consumer, which is, for example, a hydraulic cylinder, establishes a pressure medium connection from the pressure chamber, to which no pressure limiting valve is connected, to the hydraulic machine. In other words, by detecting the pressure on the pressure side of the first consumer, to which the pressure relief valve is connected, and / or the pressure at the pressure connection of the hydraulic machine, the control can estimate whether a critical operating state is occurring or has occurred, and can therefore be controlled avert the critical operating state of the hydraulic machine. One advantage of this is that both control valves can still be controlled. The pressure limitation is preferably carried out via the hydraulic machine.

An additional or alternative control measure to avoid the critical operating state can be to close the control valve of the first consumer and thus to disconnect the pressure medium connection to the pressure sides of the first consumer if the pressure in the pressure connection of the hydraulic machine exceeds a certain value. In other words, the hydraulic machine promotes a volume flow, which is demanded by another consumer, for example, so the control valve of the first consumer is not opened. This enables simple and safe control of the working hydraulics. Instead of not opening the control valve of the first consumer, it is also possible to throttle the pressure medium connection, that is to say the control valve can be activated in such a way that the pressure medium connection exists only to a limited extent.

If, during a control measure, in order to avoid the critical state, the control unit controls a control valve, it is preferable that the control unit has an algorithm for influencing the control valves. For example, the controller can have a data memory on which the algorithm is stored. The algorithm for controlling and / or influencing the control valves can, for example, determine how quickly and / or when a pressure medium connection is closed and / or how much the pressure medium connection is throttled. This can be dependent in particular on the pressures or the pressure that the pressure sensor (s) communicate / communicates with the controller. The algorithm enables precise and precise control of the control valves. It is also possible that an algorithm for controlling the hydraulic machine is also stored on the data memory.

In one embodiment, the working hydraulics can preferably be an open center working hydraulics. This means that the consumers arranged in parallel have control valves which are open for the oil flow in the middle position, so that the full delivery flow which conveys the hydraulic machine is passed through all control valves. Furthermore, the valve slides are arranged parallel to one another in this arrangement. In addition, a hydraulic control element is preferably fluidly arranged between the hydraulic machine and the consumers, which can be controlled proportionally, for example, electro-hydraulically, and which can open a pressure medium connection between the hydraulic machine and the tank in order to feed the volume flow that slides from the hydraulic machine to the consumers limit and / or control. The hydraulic control element can, for example, a control valve, in particular a 2/2-way control valve.

In a further embodiment example, the working hydraulics can be a closed-center working hydraulics, i.e. the control valves are closed in the middle position and the volume flow conveyed by the hydraulic machine is conducted, for example, via a circulation valve and / or the power of the hydraulic machine is limited.

The working hydraulics can also be equipped with a load sensing system (LS system) be equipped. The LS system is also known as a load pressure reporting system. In an open center working hydraulics, the hydraulic control element, which can be a control valve, connects to a pressure compensator and this can actuate the control element. In an open center system, the excess volume flow can be diverted to the tank by actuation. With a closed-center hydraulic system, the delivery rate of the hydraulic machine is adapted to the current requirements of one or more consumers. In this system, the pressure in the pressure connection of the hydraulic machines, which is generated by the volume flow delivery of the hydraulic machine, is controlled in such a way that the highest pressure occurring in the working hydraulics is exceeded by a certain pressure difference. Furthermore, the consumers have respective individual printing carriages which individually set a respective pressure difference via the respective control valve of a respective consumer.

Furthermore, the working hydraulics can be equipped with a flow pressure independent flow distribution (LUDV). The hydraulic machine also supplies the volume flow required by the consumers. In contrast to the LS system, however, a pressure compensator is installed downstream of the hydraulic machine, i.e. between the hydraulic machine and the control valves, so that the pressure difference across the control valve, i.e. from the hydraulic machine to the consumer, is the same for all consumers.

The controller also preferably has an input device, for example pressure sensors and / or electronic joysticks, for reading in a driver's request. The controller can thus convert the driver's request into a movement of the control valves and / or a controller of the hydraulic machine and / or, for example, inform the driver of the limitation or throttling of a pressure medium connection and / or of the hydraulic machine.

Furthermore, a method for controlling working hydraulics with this arrangement has the following steps. First, a critical operating state, which is previously defined, is recognized and / or anticipated. Thereafter, various control measures, which are mentioned above, i.e. throttling and / or closing one control valve or several control valves, so that the pressure medium connection between the consumer (s) and the hydraulic machine and / or the tank is closed and / or limited, and / or influencing the hydraulic machine, so that the critical operating state is averted or avoided.

Figure list

• 1 schematisch einen Bagger, mit dem beispielhaft ein Auftreten eines kritischen Betriebszustandes erläutert wird,
• 2 eine Anordnung einer Arbeitshydraulik gemäß einem Ausführungsbeispiel,
• 3 ein Diagramm, das beispielhaft eine Abhängigkeit zwischen einem normierten Druck in auf einer Druckseite des ersten Verbrauchers, an dem ein Druckbegrenzungsventil angeschlossen ist, und einem normierten Öffnungsquerschnitt einer Druckmittelverbindung zeigt.

Preferred exemplary embodiments of the invention are explained in more detail below with the aid of schematic drawings.

• 1 schematically an excavator with which an occurrence of a critical operating state is explained as an example,
• 2nd an arrangement of a working hydraulics according to an embodiment,
• 3rd a diagram showing an example of a dependency between a standardized pressure in on a pressure side of the first consumer, to which a pressure relief valve is connected, and a standardized opening cross section of a pressure medium connection.

1 shows an excavator 1 on a shovel 2nd a burden 4th lifts up. The excavator 1 also has an excavator body 6 on which a first hydraulic cylinder 8th who may be a first consumer. A piston rod 10th protrudes from the hydraulic cylinder 8th out and is on a boom 12th attached. Between the main body of the excavator 6 and the boom 12th is a joint arranged by the rotational movement of the boom 12th around the joint is possible. Through a movement, i.e. an extension or retraction, of the piston rod 10th in the hydraulic cylinder 8th can the boom 12th be moved around the hinge and thus one end of the boom moves 12th that is not on the excavator body 6 is arranged down or up. Weight 4th that on the shovel 2nd hangs with the boom 12th moved up and down. Furthermore, is at the end of the boom 12th that is not on the excavator body 6 is arranged, another hydraulic cylinder 14 arranged as another consumer, the piston rod 16 on an excavator arm 18th is arranged. The excavator arm 18th is through a joint with the boom 12th connected and thus it can turn around this joint. The excavator arm 18th can by moving the piston rod 16 can be rotated around the joint and thus the load 4th be moved. On the excavator arm 18th is another hydraulic cylinder 22 with a piston rod 20th arranged for movement of the bucket 2nd worries. The shovel 2nd is also through a joint with the excavator arm 18th connected so the shovel 2nd by extending or retracting the hydraulic cylinder 22 who is another consumer, can be moved.

Will the load 4th lowered, the piston rod moves 10th of the hydraulic cylinder 8th in the hydraulic cylinder 8th a, like through an arrow in 1 is indicated. By the load 4th who the hydraulic cylinder 8th holds, is the pressure in the pressure chamber of the hydraulic cylinder 8th that is not by the piston rod 10th enforced is high because the pressure in the pressure chamber of the load 4th counteracts, for example, the pressure in this pressure chamber 300 bar. By lowering the load 4th , can cause unwanted movement of the load 4th done because of the boom 12th around the joint that is on the excavator body 6 is arranged, rotates. The boom thus moves 12th not just downwards, but the excavator arm 18th is additionally tilted. This can be done, for example, by retracting the piston rod 16 that the excavator arm 18th moved, balanced. The pressure in a pressure chamber of the hydraulic cylinder 14 prevails, not by the piston rod 16 enforced can be, for example, 250 bar. Due to this simultaneous movement, the pressure chamber of the first hydraulic cylinder 8th by the piston rod 10th is penetrated, and the pressure chamber of the hydraulic cylinder 14 , in which there is a pressure of 250 bar, a pressure medium connection because of the movement of the boom 12th and the excavator arm 18th , Control valves shown in 2nd are explained in more detail, open a respective pressure medium connection to a hydraulic machine and this also results in a pressure medium connection between the pressure spaces. Due to the simultaneous opening of the control valves, the pressure in the pressure chamber of the first hydraulic cylinder increases 8th by the piston rod 10th is enforced, also to at least 250 bar. This pressure also has an effect on the pressure chamber in which 300 bar pressure prevails, since this must also compensate for the pressure. The area ratio between the area of the piston facing the pressure chamber in which 300 bar prevails is greater than the area to which the pressure in the pressure chamber acts, which is caused by the piston rod 10th is interspersed because the piston rod 10th the area is reduced because it engages the piston. The area ratio can be, for example, 2: 1, that is to say the area of the piston without a piston rod 10th is twice the area of the piston rod 10th is appropriate. Thus, the pressure in the pressure chamber in which the 300 bar pressure prevails rises by 125 bar, that is to say by half of the 250 bar. This means that the pressure in the pressure chamber is now 425 bar. A pressure relief valve that in the pressure chamber of the hydraulic cylinder 8th is arranged, for example, can open from a safety pressure of 410 bar. That means moving the boom at the same time 12th and the excavator arm 18th the pressure relief valve may open. When the pressure relief valve opens, the pressure in the pressure chamber that holds the load drops 4th stops and thus the boom lowers 12th and the burden 4th unbraked and uncontrolled down until the pressure relief valve closes again.

In 2nd is an order 24th given a working hydraulic system, such as that used for the excavator 1 out 1 is provided. The order 24th contains a first hydraulic cylinder 26 who is a first consumer, a second hydraulic cylinder 28 and a hydraulic motor 30th who are other consumers. These are arranged in fluidic parallel. Furthermore, the arrangement 24th a hydro machine 32 on that to supply consumers 26 , 28 , 30th is configured. Fluid between the hydraulic machine 32 and the respective consumer 26 , 28 , 30th is a respective control valve 34 , 36 , 38 arranged. To a respective valve spool of a respective control valve 34 , 36 , 38 center in a home position or a middle position when the respective control valve 34 , 36 , 38 valve springs are not activated 40 arranged on this. To operate the control valves 34 , 36 , 38 are two actuators each 42 , which are electromagnetic, on the respective control valves 34 , 36 , 38 arranged.

The hydraulic cylinders 26 , 28 each have a piston 44 , 46 on. The piston 44 of the hydraulic cylinder 26 separates a pressure room 48 which is a print page from a print room 50 , which is another printed page. The the pressure room 50 is one of the piston 44 extending piston rod 52 interspersed that from the hydraulic cylinder 26 protrudes. In the hydraulic cylinder 28 separates the piston 46 a pressure room 54 , which represents a print page, from a print room 56 , another pressure side, from which is also a piston rod 58 is penetrated by the piston 46 extends from.

The respective control valves 34 , 36 , 38 are 4/3-way control valves. The control valves 34 , 36 , 38 can be switchable or continuously adjustable. The control valves 34 , 36 , 38 are closed in the middle position of their valve spool, i.e. the respective consumers 26 , 28 , 30th have no pressure medium connection to the hydraulic machine 32 in the middle position. The control valves 34 , 36 , the hydraulic cylinder 26 , 28 can be switched in this way, i.e. their respective valve spool can be moved so that the pressure spaces 48 , 54 , each via a respective work connection A1 have this working connection A1 a pressure medium connection with the hydraulic machine 32 exhibit. Is the respective control valve 34 , 36 switched so, so have the respective pressure rooms 50 , 56 that have a respective work connection A2 have a pressure medium connection to the tank 60 . The control valves 34 , 36 the hydraulic cylinder 26 , 28 also have at least one other switching position in which the pressure chambers 48 , 54 with the tank 60 are connected and accordingly the pressure rooms 50 , 56 a pressure medium connection to the hydraulic machine 32 exhibit. The hydraulic motor 30th also has two working connections A1 and A2 on. Depending on how the control valve 38 is switched is the working connection A1 either with the tank 60 or the hydromachine 32 connected and the work connection A2 vice versa with the Hydro machine 32 or the tank 60 connected. This affects the direction of rotation of the hydraulic motor 30th .

The pressure rooms 48 and 50 of the hydraulic cylinder 26 are connected to a pressure relief valve 62 and 64 connected. The pressure relief valve 62 opens when the pressure in the pressure chamber 48 a safety pressure exceeds a pressure medium connection to the tank 60 . The hydraulic cylinder 26 can, for example, the hydraulic cylinder 8th out 1 correspond and the pressure chamber 48 , the pressure chamber, the hydraulic cylinder 8th which is not penetrated by the piston rod.

Furthermore, the arrangement 24th a controller 66 on. The control 66 is with an input device 68 and an input device 70 connected. The input devices 68 and 70 can be operated by a driver and these give a driver request to the control 66 further, for example lowering and / or extending the boom 12th the 1 . Furthermore, the controller 66 the pressure of at least one pressure sensor 74 communicates. This is with the pressure room 48 of the hydraulic cylinder 26 connected and gives the measured pressure to the controller 66 continue. Additionally or alternatively, a further pressure sensor can be used 76 a pressure on the controller 66 communicate. This measures the output side of a pressure connection 77 the hydromachine 32 the pressure. In other words, the pressure sensor 76 between the pressure connection 77 the hydromachine 32 and the control valves 34 , 36 , 38 arranged. The control 66 can also control valves 34 , 36 , 38 about the actuators 42 Taxes. Furthermore, the control has 66 a connection to a hydraulic machine actuator 80 . The controller can use this 66 a delivery rate of the hydraulic machine 32 determine.

A critical operating condition that causes the pressure relief valve 62 can open in this arrangement 24th arise when, for example, a load 82 on the piston rod 52 of the hydraulic cylinder 26 works. The pressure in the pressure room 48 can be 300 bar to the load in this example 84 to lift. On the piston 58 can be a load, for example 84 act that is so great that the pressure in the pressure chamber 54 is approximately 250 bar. Will the load 82 lowered, the pressure chamber points 48 a pressure medium connection to the tank 60 on and the pressure room 50 to the hydromachine 32 . That is the pressure room 50 is loaded with pressure medium and from the pressure chamber 48 pressure medium is released. Weight 84 is now being raised. That is the pressure room 54 is fed with pressure medium and the pressure chamber 56 has a pressure medium connection to the tank in order to release pressure medium. In other words, the pressure chamber points in this state 54 and the pressure room 50 and the hydro machine 32 a pressure medium connection. That means the pressure in the pressure rooms 50 , 54 can be the same. It follows that the pressure in the pressure chamber 50 250 bar. That means the pressure in the pressure chamber 48 increases since this is now the load 84 holds and also balances the pressure from the pressure chamber 50 out on a piston surface 86 of the piston 44 works. Is the area ratio of a piston area 88 that the pressure room 48 faces the piston surface 86 for example 2: 1, that is the piston area 88 is twice the piston area 88 , the pressure increases 125 bar. That means the pressure in the pressure chamber 48 increases to 425 bar. If this pressure exceeds the safety pressure above which the pressure relief valve 62 a pressure medium connection to the tank 60 opens, so it may be the load 82 that on the piston rod 52 affects the piston 44 pushes down and thus the load can 82 sink uncontrollably.

The control can handle this critical operating state 66 recognize and about the actuators 42 and the hydraulic machine actuator 80 control the arrangement in such a way that the critical state is averted. The control of the control valves 34 , 36 , 38 can also be done according to an algorithm and therefore the control 66 also a data storage 90 have, for example, at least one algorithm for controlling the control valves 36 , 36 , 38 and or to control the hydraulic machine 32 are saved. The control algorithm 66 selects, in other words the control measure the control 66 executes, may depend on the pressure in the pressure chamber 48 and / or from the pressure on the output side of the hydraulic machine 32 that the pressure sensors 74 and 76 the control 66 Report.

3rd shows an example of a relationship of a normalized pressure p in the pressure chamber 48 or in the pressure room 50 , please refer 2nd , and a standardized opening cross section Ö of the control valve 34 , s. 2nd . This relationship can, for example, on the data storage 86 the control 66 be saved, see 2nd . The pressure p is plotted in a standardized manner, that is to say a pressure p / p _{s is} plotted, p _{s being} the safety pressure at which the pressure relief valve 62 the pressure medium connection to the tank 60 opens. Furthermore, the opening cross section Ö is plotted in a standardized manner, which is related to the maximum possible opening cross section Ö _max . It can be seen that the opening cross-section that the valve spool of the control valve 34 , s. 2nd , opens more and more, the greater the pressure p is. In this embodiment, the opening cross section is Ö of the control valve 34 closed when a pressure p is 0.75 of the safety pressure. In addition, the opening cross section Ö at a pressure ratio p / p _s = 0.5 is only 25% of the maximum possible opening cross section Ö _max . In another embodiment, the relationship between p / p _s and Ö / Ö _{max could be} linear, for example.

The invention discloses an arrangement for working hydraulics, which has two hydraulic consumers, which is arranged fluidically parallel to the hydraulic cylinder. To supply the consumer, the arrangement has at least one hydraulic machine, a respective control valve for controlling the respective consumer being provided fluidly between the hydraulic machine and the respective consumer. A pressure limiting valve is connected to at least one pressure side of a first consumer, which opens a pressure medium connection to a tank from a certain safety pressure. Furthermore, a control is provided in the arrangement, which can control the control valves and the hydraulic machine. This controller is configured in such a way that it recognizes at least one operating state in which the pressure on the pressure side of the first consumer would reach or exceed the safety pressure due to activation of the consumers and / or due to load states of the consumers. If this occurs, the control avoids at least one operating state by taking control measures for at least one of the control valves or more of the control valves or more of the control valves and / or the hydraulic machine.

Claims (15)

Arrangement for working hydraulics, the at least two hydraulic consumers (8, 14, 22, 26, 28, 30) arranged fluidly parallel to one another and at least one hydraulic machine (32) for supplying the consumers (8, 14, 22, 26, 28, 30 ), with a respective control valve (34, 36, 38) for controlling the respective consumer (8, 14, 22,) between the hydraulic machine (32) and the respective consumer (8, 14, 22, 26, 28, 30) 26, 28, 30) is provided, and a pressure limiting valve (62, 64) is connected to at least one pressure side (48, 50, 54, 56) of the first consumer (8, 14, 22, 26, 28, 30), which opens a pressure medium connection to a tank (60) from a certain safety pressure on the pressure side (48, 50, 54, 56), a controller (66) being provided for controlling the control valves (34, 36, 38) and the hydraulic machine (32) , characterized in that the controller (66) detects at least one operating state in which the pressure of the pressure ite (48, 50, 54, 56) of the first consumer (8, 14, 22, 26, 28, 30) due to activation of the consumers (8, 14, 22, 26, 28, 30) and / or due to load conditions the consumer (8, 14, 22, 26, 28, 30) would reach or exceed the safety pressure, and that the controller (66) would control this at least one operating state through control measures of at least one of the control valves (34, 36, 38) or more of the control valves (34, 36, 38) and / or the hydraulic machine (32) is avoided. Arrangement after Claim 1 , At least one pressure sensor (74, 76) being provided, by means of which the control (66) detects the operating state. Arrangement according to one of the Claims 1 or 2nd , The respective control valves (34, 36, 38) being directly or indirectly electronically controllable. Arrangement according to one of the Claims 1 to 3rd , wherein the consumers (8, 14, 22, 26, 28, 30) each have two working connections (A1, A2). Arrangement after Claim 4 , wherein the control valves (34, 36, 38) each have a valve slide, which in a first or in the first switching position (s) has a first working connection (A1, A2) of the associated consumer (8, 14, 22, 26, 28, 30) with the hydraulic machine (32) and a second working connection (A1, A2) of the assigned consumer (8, 14, 22, 26, 28, 30) with the tank (60) and which in one or in the second switching position / s reversely connects the first working connection (A1, A2) of the assigned consumer (8, 14, 22, 26, 28, 30) with the tank (60) and the second working connection (A1, A2) of the assigned consumer (8, 14, 22, 26, 28, 30) with the hydraulic machine (32). Arrangement according to one of the Claims 1 to 5 , wherein at least one of the consumers (8, 14, 22, 26, 28, 30) is designed as a hydraulic cylinder. Arrangement according to one of the Claims 1 to 6 , wherein the controller (66), in order to avert the critical operating state, controls one of the consumers (8, 14, 22, 26, 28, 30) or both consumers (8, 14, 22, 26, 28, 30) in a throttled manner or one Pressure medium connection from the hydraulic machine (32) to one of the consumers (8, 14, 22, 26, 28, 30) or both consumers (8, 14, 22, 26, 28, 30) blocks. Arrangement according to one of the Claims 1 to 7 , wherein the hydraulic machine (32) has a pressure connection (77), and wherein the or at least one pressure sensor (74, 76) is connected on the outlet side of the pressure connection (77), which reports this pressure to the controller (66). Arrangement according to one of the Claims 1 to 8th , wherein the controller (66) electronically controls a volume flow of the hydraulic machine (32). Arrangement according to one of the Claims 8 or 9 , wherein the controller (66), in order to avert the critical operating state, controls the hydraulic machine (32) in such a way that the pressure on the outlet side of the pressure connection (77) is limited. Arrangement according to one of the Claims 8 to 10th , wherein the controller (66), in order to avert the critical operating state when the pressure tapped on the outlet side of the pressure connection of the hydraulic machine (32) exceeds a predetermined limit pressure, the pressure medium connection between the hydraulic machine (32) and the first consumer (8, 14, 22, 26, 28, 30) throttles or blocks. Arrangement according to one of the Claims 1 to 11 The controller (66) has an input device (68, 70) that controls the position of the control valves (34, 36, 38). Arrangement according to one of the Claims 1 to 12th , wherein the working hydraulics have valve slides arranged parallel to one another and a hydraulic control element is arranged fluidly between those of the hydraulic machine and the tank. Method for controlling (66) working hydraulics with the arrangement according to one of the Claims 1 to 13 comprising the steps: - anticipating and / or recognizing the critical operating state, - carrying out control measures to avoid at least one of the control valves (34, 36, 38) or more of the control valves (34, 36, 38) and / or the hydraulic machine (32) or averting the critical operating state. Working hydraulics with the arrangement according to one of the Claims 1 to 13 .

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