DE102019203068C5 - Mobile crane and method for setting a brake pressure in such a mobile crane - Google Patents

Abstract

mobile crane includinga. a mobile undercarriage (2) with a plurality of axles (9) each having two wheels (10), b. a plurality of sensor elements (19, 24) for determining a set-up state of the mobile crane (1) described by mounting additional components (13, 22) on the mobile crane (1), c. a control unit (38) with a signal connection to the sensor elements (19, 24) for specifying a control signal as a function of the determined set-up status, d. a brake unit (26) in signal communication with the control unit (38) miti. at least one pressurized braking element (34, 35) for braking a wheel (10), ii. a pressure valve (30; 30a) upstream of the braking element (34, 35) for providing a braking pressure (p2) for the braking element (34, 35),iii. a control valve (32; 32a) for adjusting the braking pressure (p2) depending on the control signal a control unit with a signal connection to the at least one sensor element for specifying a control signal depending on the determined setup status, and a brake unit (26) with a signal connection to the control unit with at least one brake element (34, 35) to which pressure is applied for braking a wheel (10), with a pressure valve (30) upstream of the braking element (34, 35) for providing a braking pressure for the braking element (34, 35) and with a control valve (32) for adjusting the braking pressure as a function of the control signal.

Description

The invention relates to a mobile crane and a method for adjusting a braking pressure in such a mobile crane.

EP 2 712 837 B1 discloses a self-propelled work machine. DE 198 59 737 A1 discloses a hydraulic braking system for wheeled equipment.

In a mobile crane, the brake unit is designed in such a way that the mobile crane can be braked reliably in a set-up state in which the mobile crane has a maximum total weight. In order to ensure this, the braking unit provides the maximum braking force required for this configuration.

It is the object of the present invention to improve the braking behavior of a mobile crane as a function of its configuration.

According to the invention, this object is achieved by a mobile crane having the features specified in claim 1 and by a method having the features specified in claim 13 . According to the invention, it was recognized that an adapted braking force can be made available in a mobile crane depending on the configuration. The mobile crane has a brake unit, which has at least one brake element to which pressure is applied, in particular a brake cylinder activated by compressed air. The braking element is used to brake a wheel. in particular, a braking element is provided for each wheel. In order to determine the setup status of the mobile crane, a number of sensor elements are provided which have a signal connection to a control unit. In particular, the sensor elements generate control signals that are transmitted to the control unit. The control unit specifies a control signal as a function of the determined set-up status, in particular as a function of the actuating signals of the sensor elements. The control unit is in signal communication with the brake unit, so that the control signal is transmitted from the control unit to the brake unit. A braking pressure for the braking element is set by a control valve as a function of the control signal. The braking pressure is in particular a maximum braking pressure, which therefore corresponds to the maximum braking force acting on the wheel. The braking pressure is provided at the braking element by means of a pressure valve. in particular, the brake element is connected to the pressure valve via a brake line. The pressure valve is in particular connected directly to the control valve via a control line. in particular, the maximum brake pressure is reduced to a reduced brake pressure by the control valve for a reduced setup state. Since a reduced braking pressure is made available for the at least one braking element, an undesired locking of the wheel braked by means of the braking element is prevented. The braking behavior of the mobile crane has been improved and, in particular, adapted to the respective set-up status.

According to the invention, it is thus ensured that an adapted braking force is made available for the respective configuration of the mobile crane. On the one hand, the braking force provided is sufficient, i.e. large enough, to reliably brake the mobile crane in the respective setup state. On the other hand, the braking force is only so great that the wheels cannot lock. In particular, it was recognized according to the invention that a maximum braking force, which is required for a mobile crane in a maximum set-up state with a maximum total weight, is correspondingly reduced for the mobile crane in a reduced set-up state with a reduced total weight. With the multiple sensor elements, it is possible to reliably record the current set-up status of the mobile crane.

In particular, several, in particular exactly two, in particular exactly three, in particular exactly four, in particular exactly five, discrete set-up states are predefined for the mobile crane.

The mobile crane has a mobile undercarriage with several travel axles. In particular, the mobile undercarriage has at least five, in particular six, travel axles. Two wheels are arranged on each axle, one wheel can also be designed as a double wheel. The sensor element is attached in particular to the undercarriage.

A brake unit according to claim 2 reduces the risk of failure. in particular, the brake unit has two brake circuits.

The provision of a braking force is reliably possible. In particular, the brake circuits are designed to be independent of one another. In particular, the brake circuits are each charged with compressed air from their own separate compressed air tank. It is essential that each of the brake circuits has at least one brake element, so that at least two brake elements can each be subjected to pressure independently of one another. Each brake circuit can have several brake elements. in particular, exactly two brake circuits are provided, with the number of brake elements per brake circuit being substantially and in particular exactly distributed equally. in particular, each brake circuit has a Pressure valve and a control valve. In particular, each brake circuit has exactly one pressure valve and exactly one control valve. In particular, it is not necessary to provide multiple pressure valves and/or multiple control valves per brake circuit.

A control unit according to claim 3 simplifies the assignment of the set-up status. in particular, two predefined set-up states are stored in the data memory. in particular, the setup status can be determined automatically. in particular, the control signals provided by the sensor elements enable the automated assignment of a predefined set-up state.

A sensor element according to claim 4 enables the setup status to be determined reliably and robustly. A position switch can be used to reliably determine whether additional components that describe a specific configuration are attached to the mobile crane. It is advantageous if the sensor elements are attached to an upper side of the undercarriage. Depending on the set-up states to be monitored, several sensor elements can also be provided, which can also be arranged, for example, on an upper carriage that can be connected to the undercarriage. In particular, a sensor element for length measurement and/or a sensor element for angle measurement, which is already present on a mobile crane and is already used, for example, for operating other crane functions, can also be used as a sensor element for determining the set-up status.

A pressure valve according to claim 5 enables reliable and robust provision of the brake pressure. The pressure valve is designed in particular as a load/empty valve.

A control valve according to claim 6 has an uncomplicated and robust design. For example, the control valve can be designed as a 3/2-way solenoid valve, which is in an open state, particularly when there is no current. This control valve enables a simplified change between two specific set-up states. Starting from a maximum set-up state, in which the mobile crane has a maximum total weight, the maximum brake pressure provided can be adjusted, in particular reduced, by actuating the control valve and thereby in particular enabling venting of the pressure valve.

Alternatively, the control valve can also be designed as a proportional 3/2-way valve that can be actuated, in particular, electrically. The proportional 3/2-way valve is in particular de-energized in a closed state. The proportional 3/2-way valve allows stepless pressurization of the pressure valve. As a result, the brake pressure provided by the pressure valve can be adjusted, in particular steplessly.

A reservoir according to claim 7 ensures a reliable pressure supply for the control valve. In this case, the control valve is designed in particular as a proportional 3/2-way valve. in particular, the pressure supply is constant. In particular, this enables pressure regulation that is as uniform as possible for the provision of the braking pressure.

An electromechanical evaluation unit according to claim 8 enables reliable and redundant detection of the set-up status. An erroneous detection of the setup state, which could lead, for example, to an undesired provision of too low a braking force for a heavy, in particular fully loaded, setup state, is ruled out.

A monitoring circuit according to claim 9 increases system security. In particular, the monitoring circuit has a reporting unit for transmitting a fault signal to a warning unit. In particular, a fault signal can be transmitted to a crane operator and/or crane driver.

A pressure sensor according to claim 10 is used for self-monitoring of the brake unit. in particular, several pressure sensors are provided, which can be arranged in different positions in the brake unit. in particular, a pressure sensor is arranged on the control line between the control valve and the pressure valve. A pressure sensor can also be arranged on the pressure line which connects the pressure valve to the braking element. A pressure sensor can also be placed before the inlet of the pressure valve. The pressure sensors enable error monitoring.

An integral structural component according to claim 11 allows a simplified and uncomplicated retrofitting of a braking unit in an existing mobile crane. The structural component can in particular include one or more pressure sensors for pressure detection. In particular, it is conceivable to provide a single pressure sensor that monitors multiple pressure lines.

A mobile crane according to claim 12 enables improved fault monitoring.

A method according to claim 13 essentially has the advantages of the mobile crane, to which reference is hereby made.

Both the features specified in the patent claims and the features specified in the following embodiments of the mobile crane according to the invention are each suitable, alone or in combination with one another, to develop the subject according to the invention. The respective combinations of features do not represent any limitation with regard to the developments of the subject matter of the invention, but essentially only have an exemplary character

• 1 eine perspektivische Ansicht eines erfindungsgemäßen Mobilkrans in einem ersten, reduzierten Rüstzustand,
• 2 eine vergrößerte Detaildarstellung des Details II in 1,
• 3 eine Seitenansicht des Mobilkrans in
• 1 in einem zweiten, maximalen Rüstzustand,
• 4 eine perspektivische Ansicht des Mobilkrans in 1 in einem dritten, teilreduzierten Rüstzustand,
• 5 eine schematische Darstellung einer Warneinheit, die insbesondere im Fahrerhaus des Mobilkrans angeordnet ist,
• 6 ein Schaltplan einer Bremseinheit des Mobilkrans in 1,
• 7 eine vergrößerte Detaildarstellung des Details VII in 6,
• 8 ein Funktionsdiagramm zur Darstellung der Abhängigkeit eines von einem Druckventil bereitgestellten Bremsdrucks vom Eingangsdruck des Druckventils,
• 9 einen elektrischen Schaltplan des Mobilkrans,
• 10 ein 6 entsprechender Schaltplan einer Bremseinheit gemäß einer weiteren Ausführungsform,
• 11 eine vergrößerte Detaildarstellung des Details XI in 10,
• 12 ein 8 entsprechendes Funktionsdiagramm zur Darstellung der funktionellen Abhängigkeit des Druckventils vom vorgegebenen Steuerdruck,
• 13 ein 12 entsprechendes Diagramm zur Darstellung der funktionalen Abhängigkeit eines Steuerventils der Bremseinheit gemäß der zweiten Ausführungsform,
• 14 eine schematische Darstellung einer Steuerungsübersicht eines Mobilkrans mit der Bremseinheit gemäß der zweiten Ausführungsform und
• 15 eine 11 entsprechende Darstellung eines Kombinationsgeräts für eine Bremseinheit gemäß einer weiteren Ausführungsform.

Advantageous configurations and details of the invention result from the following description of exemplary embodiments with reference to the drawing. Show it:

• 1 a perspective view of a mobile crane according to the invention in a first, reduced set-up state,
• 2 an enlarged detailed view of detail II in 1 ,
• 3 a side view of the mobile crane in
• 1 in a second, maximum set-up state,
• 4 a perspective view of the mobile crane in 1 in a third, partially reduced set-up state,
• 5 a schematic representation of a warning unit, which is arranged in particular in the driver's cab of the mobile crane,
• 6 a circuit diagram of a brake unit of the mobile crane in 1 ,
• 7 an enlarged detailed view of detail VII in 6 ,
• 8th a function diagram to show the dependency of a brake pressure provided by a pressure valve on the input pressure of the pressure valve,
• 9 an electrical circuit diagram of the mobile crane,
• 10 a 6 Corresponding circuit diagram of a braking unit according to a further embodiment,
• 11 an enlarged detail view of detail XI in 10 ,
• 12 a 8th Corresponding function diagram to show the functional dependency of the pressure valve on the specified control pressure,
• 13 a 12 Corresponding diagram to show the functional dependency of a control valve of the brake unit according to the second embodiment,
• 14 a schematic representation of a control overview of a mobile crane with the brake unit according to the second embodiment and
• 15 one 11 Corresponding representation of a combination device for a braking unit according to a further embodiment.

The following is based on 1 until 9 a first embodiment of a mobile crane according to the invention, which is denoted as a whole by 1, explained in more detail. The mobile crane 1 includes an undercarriage 2 with a driver's cab 3, a boom support 4 and a counterweight shelf 5. The undercarriage 2 also includes telescopic support beams 6, on each of which an extendable support cylinder 7 with a support plate 8 attached thereto are provided.

According to the exemplary embodiment shown, the undercarriage 2 comprises six travel axles 9, on each of which two wheels 10 are attached.

A rotary mount 12 is provided on an upper side 11 of the undercarriage 2 , on which a superstructure 13 can be connected to the undercarriage 2 so as to be rotatable about an axis of rotation 14 by means of a slewing gear 15 .

The superstructure 13 comprises a luffing main boom 16 which has a plurality of telescopic parts 17 which can be telescoped in and out. The main boom 16 is supported on the undercarriage 2 at the boom support 4 . Two sensor elements 19 are arranged on the boom support 4 on a support surface 18 facing the main boom 16 . According to the exemplary embodiment shown, the sensor elements 19 are designed as position switches.

A rear support unit 22 can be coupled to the undercarriage 2 at its rear end 20, which is arranged opposite the driver's cab 3 in the direction of travel 21 of the undercarriage 2. The rear support unit 22 has a support beam 6 with a support cylinder 7 and a support plate 8 opposite each other transversely to the direction of travel 21 .

Two sensor elements 24 are arranged at the rear end 20 on the upper side 11 of the undercarriage 2 . The sensor elements 24 make it possible to determine whether the support unit 22 is coupled to the undercarriage 2 .

A warning unit 25 is arranged in the driver's cab 3, in particular in the area of the fittings, in order to signal a warning situation to the driver of the crane. The warning unit 25 includes, in particular, optical and/or acoustic display instruments.

A warning unit 25 is arranged in the driver's cab 3, in particular in the area of the fittings, in order to signal a warning situation to the driver of the crane. The warning unit 25 includes, in particular, optical and/or acoustic display instruments.

The mobile crane 1 can be configured in different configurations. In 3 the mobile crane 1 is shown in a first set-up state. In this set-up state, both the superstructure 13 and the rear support unit 22 are mounted on the undercarriage 2 . In this first set-up state, the mobile crane 1 is loaded to the maximum and has a total weight of at least 72 t, for example. The first set-up state is also referred to as the maximum set-up state. In the maximum set-up state, the axle load for the travel axles 9 is maximum.

In another, not shown in the figures set-up state, the mobile crane 1 accordingly 3 be arranged, with the rear support unit 22 being carried along separately from the mobile crane 1, ie not mounted on the undercarriage 2. In addition, an auxiliary hoist is provided on the mobile crane 1 . In this set-up state, the mobile crane 1 has a total weight of exactly 72t.

In 1 the mobile crane 1 is shown in a second set-up state. In the second set-up state, no additional set-up components are mounted on the undercarriage 2 with the exception of the rotary mount 12 . In the second set-up state, the mobile crane 1 is designed without an upper carriage 13, without a rear support unit 22 and without a luffing cylinder. The second set-up state is also referred to as the minimum set-up state. In the minimum set-up state, the total weight is 40 t. In the minimum set-up state, the axle load for the travel axles 9 is minimal.

In 4 the mobile crane 1 is shown in a third set-up state. The rear support unit 22 is mounted on the undercarriage 2 in the third set-up state. The third setup state is referred to as the intermediate setup state. The total weight in the third set-up state is between the total weight in the maximum set-up state and that in the minimum set-up state.

The rear support unit 22 and the superstructure 13 are set-up components that can be mounted on the substructure 2 independently of one another. Additionally or alternatively, a folding jib for the main boom 16, counterweights and/or an auxiliary hoist can also be used as set-up components, which are mounted directly on the undercarriage 2 or on the superstructure 13.

Other setup states are possible, in which at least one setup component 13, 22 and in particular several setup components 13, 22 can be mounted on the undercarriage 2 independently of one another and in any variation.

To brake the wheels 10 of the mobile crane 1 is a brake unit 26, which is based on the below 6 until 9 is explained in more detail. The brake unit 26 has two brake circuits 27, which in particular function identically and are designed in particular identically. Each brake circuit 27 includes a pressure tank 28 which is connected to a pressure valve 30 via a supply line 29 . Compressed air is stored under pressure in the pressure vessel 28 .

A respective control valve 32 is connected to the pressure valve 30 via a control line 31 . The pressure valve 30 is connected to a plurality of braking elements 34 , 35 via a pressure line 33 . By applying pressure to the braking elements 34, 35 by providing a braking pressure p ₂ from the pressure valve 30, the braking elements 34, 35 are activated. The braking elements 34, 35 are each arranged in the area of the wheels 10. The braking elements 34, 35 serve to brake the wheels 10.

According to the exemplary embodiment shown, the brake elements 34, which are arranged on the wheels 10 of the two front axles 9 viewed in the direction of travel 21, are designed as duplex expanding part brakes. Two separate brake cylinders are provided for each wheel 10 . On the wheels 10 of the four rear axles 9 viewed in the direction of travel 21, the braking elements 35 are each designed as simplex expanding part brakes. A brake cylinder is provided for each wheel 10 .

The control valve 32 is fed by a feed line 36 to specify a control pressure. According to the exemplary embodiment shown, the feed line 36 is connected to the supply line 29 . The feed line 36 is a control line.

The different brake elements 34, 35 of the first brake circuit 27 are each connected to separate pressure vessels 28. For this reason, the first brake circuit 27 has two pressure vessels 28, which can have different volumes, for example. It is also conceivable to provide only a single pressure vessel 28 for the second brake circuit 27, in particular if all brake elements are of the same type, in particular identical, as is the case with the first brake circuit 27.

The following are based on 7 explain the pressure valve 30 and the control valve 32 in more detail third According to the exemplary embodiment shown, the pressure valve 30 is designed as a load/empty valve. An input pressure p ₁ is applied to the pressure valve 30 via the supply line 29 . Pressure valve 30 delivers brake pressure p ₂ to brake line 33 . The brake line 33 is a pressure line. The braking pressure p ₂ is adjusted by means of the load/empty valve, in particular by means of an actuating element 37 integrated therein. To set the adjusting element 37 , the control valve 32 is connected to the pressure valve 30 via the control line 31 .

The control valve 32 is designed as a 3/2-way solenoid valve. The 3/2-way solenoid valve is as in 7 shown in the de-energized state in an open position. In the open position, the control pressure that is provided at the control valve 32 via the feed line 36 is delivered to the load/empty valve, in particular its actuating element 37 .

According to the embodiment shown, the load/empty valve has an in 8th shown control behavior. If the load/empty valve, as in 7 shown, is acted upon by the control valve 32 with a control pressure p ₄ , the brake pressure p ₂ is identical to the input pressure p ₁ . Since the feed line 36 is connected directly to the supply line 29, the control pressure p ₄ is also identical to the input pressure p ₁ and thus also to the brake pressure p ₂ .

By actuating the control valve 32, the load/empty valve 30 is vented. The actuating element 37 is then pressureless, so that the control pressure p ₄ is 0 bar. This condition is shown in the diagram 8th shown as a dashed line. The braking pressure p ₂ is lower than the input pressure p ₁ . According to the exemplary embodiment shown, the load/empty valve 30 enables a pressure reduction of 1:1.35.

Depending on the desired braking behavior, other load/empty valves can be used that allow a smaller or larger pressure reduction.

The following is based on the 9 a control unit 38 explained in more detail. The control unit 38 is based on the electrical circuit diagram in 9 shown schematically. A two-channel first control element 39 and a two-channel second control element 40 serve to control the control valves 32. The control valves 32 are controlled in both supply lines, the positive path and the ground path of the control valves 32. The first control element 39 and the second control element 40 each have two Test thread 42 in connection. A relay 43 with a changeover contact 44 is provided on each test path 42 .

A monitoring circuit 45 is used for the plausibility check. The monitoring circuit 45 is designed as a logic circuit in order to monitor the two-channel activation of the activation elements 39, 40.

If the states of the changeover contacts 44 in the test paths 42 differ, an electrical fault is identified. In the event of an electrical fault, the two-channel control ensures that the high brake pressure p ₂ is always provided, ie the control pressure p ₄ =p ₁ applies, since in this case the two control valves 32 are not energized. An electrical fault can be caused, for example, by a broken cable, a defective component, a loss of supply voltage and/or a fault in the sensor system.

The electrical faults can be reported to the warning unit 25 by a signaling relay 41 and displayed to the driver in the driver's cab 3 via the display instruments.

The control unit is connected to the control valves 32 as in 9 shown in signal connection. The signal connection can be wireless or wired. According to the exemplary embodiment shown, the signal connection is wired.

The control unit 38 is connected to the sensor elements 19, 24 in a wired signal connection. The signal connection can also be wireless.

The control unit 38 comprises an electromechanical evaluation unit 46 and a sensor system 47 with a signal connection thereto. The electromechanical evaluation unit 46 comprises the two-channel activation elements 39, 40 for activating the control valves 32, the monitoring circuit 45 and the signaling relay 41. The signaling relay 41 represents a signaling unit.

The sensor system includes two redundant sensor paths 48. A sensor element 19 and a sensor element 24 as well as a sensor relay 49 are connected in series along each sensor path 48 one behind the other.

A method for setting the braking pressure p ₂ in the mobile crane 1 is explained in more detail below. First, the setup status of the mobile crane 1 is detected by means of the sensor elements 19 , 24 . If the sensor elements 19, 24 are triggered by the main boom 16 of the superstructure 13 and the rear support unit 22, a corresponding corresponding switching signal is generated and transmitted to the electromechanical evaluation unit 46 of the control unit 38 via the signal connection. In the evaluation unit ₄₆ , the control valves 32 are de-energized, so that the input pressure p ₁ , ie a maximum braking pressure p _{2,max ,} is present as the braking pressure p 2 . The maximum brake pressure p _2,max is suitable for reliably braking the mobile crane 1 in the maximum set-up state.

In the event that not all sensors generate an actuating signal, the redundant design of the sensor paths 48 in the sensor system 47 ensures that the control valves 32 nevertheless remain de-energized.

If the undercarriage 2, as in 1 , shown is in the second set-up state, the sensor elements 19 and 24 are not switched, so that the control valves 32 are switched. The control pressure p ₄ =p ₁ is then present at the control input of the load/empty valve 30 . According to the 8th The characteristic shown is the brake pressure p ₂ stocky. This reduced braking pressure p _2,red is suitable for reliably braking the mobile crane 1 in the reduced set-up state. At the same time, the reduced brake pressure p _2,red prevents the wheels 10 of the mobile crane 1 from locking when braking.

The following is based on 10 until 14 another embodiment of the invention is described. Structurally identical parts are given the same reference numbers as in the first embodiment, to the description of which reference is hereby made. Structurally different, but functionally similar parts are given the same reference numbers with a suffix a.

The main difference from the first embodiment is the design and interaction of pressure valves 30a and control valves 32a.

The control valves 32a are each designed as an electrically controllable, proportional 3/2-way valve, in particular as a pulse width modulation valve, which is also referred to as a PWM valve. The PWM valve 32a is designed in such a way that it can steplessly apply a control pressure p ₄ to the control input of the pressure valve 30a.

The characteristic curve of the PWM valve 32a is in 13 shown schematically. A control pressure p ₄ is generated as a function of a control current I. The PWM valve 32a is closed in the currentless state (I=0). This means that in the de-energized state, a control pressure p ₄ =0 is provided. A corresponding bypass valve 50, which is part of the pressure valve 30a, directs the input pressure p ₁ as brake pressure p ₂ through the pressure valve 30a when the control valve 32a is de-energized.

Because different control pressures p ₄ can be provided with the PWM valve 32a, different characteristic curves of the brake pressure p ₂ result for the pressure valve 30a as a function of the input pressure p ₁ . These characteristics are in 12 shown. As explained above, the characteristic curves are identical at maximum control pressure (p ₄ =p ₁ ) and at minimum control pressure (p ₄ =0 bar).

Another difference from the previous embodiment is that the control valve 32a is connected via the feed line 36a as a supply line. The feed line 36a is connected in particular to the pressure vessel 28 . This ensures a constant supply of pressure to the control valve 32a. Due to the constant pressure supply to the control valve 32a, the control of the control pressure p ₄ for the pressure valve 30a can be improved, in particular as evenly as possible.

It is advantageous if the control valve 32a only applies the control pressure p ₄ to the pressure valve 30a when a deceleration request, ie an actuation of the brake pedal, is detected with the aid of a first pressure sensor 51 . The first pressure sensor 51 is arranged along the supply line 29 between the pressure tank 28 and the pressure valve 30a.

A second pressure sensor 52 is arranged along the control line 31 between the control valve 32a and the pressure valve 30a. The second pressure sensor 52 serves to monitor the control pressure p ₄ provided by the control valve 32a.

A third pressure sensor 53 is arranged along the brake line 33 between the pressure valve 30a and the brake elements 34,35. The third pressure sensor 53 is used to monitor the brake pressure p ₂ provided by the pressure valve 30a.

The fact that the brake unit 26 has two separate brake circuits 27 makes it possible to provide different brake pressures p ₂ for the individual brake circuits 27 .

According to this embodiment, it is possible to take into account not just two, but several setup states when adapting the brake pressure p ₂ . In particular, the brake pressure p ₂ can be set automatically for each set-up state. All possible setup states of the mobile crane 1 are calculated, defined and clearly and reliably recognized by the control unit 38 .

The set-up states are recorded by means of the sensor elements 19, 24. The sensor elements 19, 24 can be arranged on the undercarriage 2 and in particular also in or on the superstructure 13. In particular, it is conceivable to use sensors that are already present on the mobile crane 1, in particular length sensors and/or angle sensors, for detecting the set-up status.

Advantageously, the sensor data are transmitted analogously or digitally to redundant safety computers 55 by means of a bus system, such as CAN Open Safety or Ethernet. The set-up states can be evaluated in the redundant safety computers 55 on the basis of configuration data such as the weight and center of gravity of the mobile crane 1 . The associated axle loads for the mobile crane 1 are determined on the basis of the setup status determined. A cross comparison is used to check sensor data and the results from the safety computers for plausibility.

In addition, a self-monitoring system 60 is specified, which checks the control unit 38 and its components, in particular sensor elements 19, 24, valves, lines and supply voltages, at regular time intervals. The self-monitoring includes in particular an active monitoring and diagnosis of the control valves 32a. The control pressures p ₄ in the control lines 31 are set as a function of the actuation of the control valves 32a. The control valves 32a can be monitored indirectly by means of the second pressure sensors 52 arranged there, which are evaluated by means of the two safety computers 55.

A further error monitoring of the brake unit 26 takes place by means of the first pressure sensor 51, which is connected upstream of the pressure valve 30a.

The third pressure sensors 53 can be used to compare the actual brake pressure p _2,actual with a setpoint characteristic curve p _2,setpoint . Errors that occur can be stored in the safety computers 55, in particular in an electronic memory module of the safety computers 55. The errors diagnosed are reported to the display instruments of the warning unit 25 by means of the bus system 54 . Depending on the error status, it may be necessary for the redundant safety computer 55 to intervene. The redundant safety computer 55 makes it possible to restore the functionality of the braking unit 26 .

In the event of critical errors such as a power failure, a safety mode, a so-called fail-safe mode, is activated so that the brake unit 26 provides the maximum brake pressure p _2,max . This critical fault is also reported to the driver, with direct wiring 56 to the display instruments of warning unit 25 also being provided for safety reasons. The safety system 60 is designed in such a way that a message is sent to the driver if the power supply is interrupted. As input signals for the control system according to 14 On the undercarriage 2, the pressure sensors 51, 52, 53 of the brake circuits 27, a travel sensor 57 of the brake pedal in the mobile crane 1 and other elements that can provide relevant data such as the engine control 61, the transmission 62, a diagnostic unit 63 or the undercarriage sensors 64 are used.

Input data from the upper carriage 13 for the safety system 60 can originate, for example, from the upper carriage sensor system, which is used, for example, for luffing and/or telescoping the main boom 16 . Diagnostic signals from the superstructure and/or other additional equipment components that can be connected to the undercarriage 2 can also be used and fed into the safety system 60 via the bus system 54 . The data sources of the superstructure 13 are in 14 identified by the reference numeral 58.

The following is based on 15 another embodiment of the invention is described. Structurally identical parts are given the same reference numbers as in the previous embodiments, the description of which is hereby referred to. Structurally different but functionally similar parts are given the same reference numbers with a suffix b.

According to 15 the pressure valve 30a, the control valve 32a and the pressure sensors 51, 52, 53 are combined in an integral structural component 59. The integral structural component 59 is connected to the pressure vessel 28 via the supply line 29 and the feed line 36a. The structural component 59 is connected to the brake elements 34 , 35 via the brake line 33 .

Claims (13)

Mobile crane comprising a. a mobile undercarriage (2) with a plurality of axles (9) each having two wheels (10), b. several sensor elements (19, 24) for determining a setup state of the mobile crane (1) described by mounting additional components (13, 22) on the mobile crane (1), c. a control unit (38) with a signal connection to the sensor elements (19, 24) for specifying a control signal as a function of the determined set-up status, d. a braking unit (26) in signal communication with the control unit (38), with i. at least one pressurized braking element (34, 35) for braking a wheel (10), ii. a pressure valve (30; 30a) upstream of the braking element (34, 35) for providing a braking pressure (p2) for the braking element (34, 35), iii. a control valve (32; 32a) for adjusting the brake pressure (p2) as a function of the control signal. mobile crane according to claim 1 , wherein the brake unit (26) has a plurality of brake circuits (27), each brake circuit (27) having at least one brake element (34, 35). Mobile crane according to one of the preceding claims, wherein the control unit (38) comprises a data memory in which a plurality of predefined set-up states are stored. Mobile crane according to one of the preceding claims, wherein the sensor element (19, 24) is designed as a position switch. Mobile crane according to one of the preceding claims, wherein the pressure valve (30; 30a) is designed as a pressure-reducing valve with external control. Mobile crane according to one of the preceding claims, wherein the control valve is designed as a 3/2-way valve (32, 32a). Mobile crane according to one of the preceding claims, wherein the control valve (32; 32a) is connected to a storage tank (28) via a feed line (36a). Mobile crane according to one of the preceding claims, wherein the control unit (38) comprises an electromechanical evaluation unit (46) with a two-channel activation of the control valves (32; 32a). mobile crane according to claim 8 , wherein the electromechanical evaluation unit (46) has a monitoring circuit (45) for the plausibility check. Mobile crane according to one of the preceding claims, wherein the brake unit (26) has at least one pressure sensor (51, 52, 53) for pressure detection. Mobile crane according to one of the preceding claims, wherein the pressure valve (30; 30a) and the control valve (32, 32a) are combined in an integral structural component (59). mobile crane according to claim 10 or 11 , wherein two with the at least one pressure sensor (51, 52, 53) standing in signal connection safety computer (55) are provided for fault monitoring. Method for setting a brake pressure in a mobile crane according to one of the preceding claims with the method steps - Determination of a setup state of the mobile crane (1) described by mounting additional components (13, 22) on the mobile crane (1) by means of the sensor elements (19, 24), - specification of a control signal depending on the determined set-up state by means of the control unit (38) which is in signal connection with the sensor elements (19, 24), - Setting a brake pressure (p2) depending on the control signal by means of the control valve (32; 32a), - Providing a braking pressure (p2) for the braking element (34, 35) by means of the pressure valve (30; 30a).

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