Method for damping vibrations of an attachment on a mobile working machine
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- BUCHER HYDRAULICS GMBH
- Filing Date
- 2025-04-04
- Publication Date
- 2026-06-10
AI Technical Summary
Existing methods for damping vibrations in mobile work machines with hydraulic lifting gear and attachments require additional equipment and sensors, which are inefficient and can lead to loss of control and reduced driving safety.
A method using a controllable hydraulic valve to regulate pressure in hydraulic working cylinders by monitoring the difference between target and actual pressure values, allowing efficient vibration damping without additional sensors, using existing hydraulic components.
Effectively reduces vibrations in lifting gear and attachments, improving driving safety and comfort by continuously regulating pressure to counteract vibrations, especially during road travel and field work.
Smart Images
Figure EP2025059363_16102025_PF_FP_ABST
Abstract
Description
[0001] Method for damping vibrations of an attachment on a mobile work machine
[0002] The invention relates to the active vibration damping of mobile work machines which have a hydraulic lifting gear with an attachment or to which a hydraulic lifting gear and / or an attachment can be coupled.
[0003] Electro-hydraulic hitch control for mobile work machines, such as tractors, has been established in agricultural technology for years. The main tasks of hitch control are, on the one hand, to achieve a consistent working depth for an attachment linked or coupled to the hitch during operation. For example, a plow as a coupled attachment should always plow into the soil / ground at a specified depth. On the other hand, the compensation or elimination of vibrations that occur during driving in the overall system consisting of the mobile work machine and the attachment is of great importance. Such vibrations are caused in particular by the condition of the road surface and the driving maneuvers of the mobile work machine. For example, if the mobile work machine drives over bumps on the road, it can vibrate.The geometry and weight of common attachments on such mobile work machines significantly influence the vibration characteristics of the overall system.
[0004] Particularly in the case of large attachments carrying heavy loads, it is even possible that vibrations may cause the front and / or rear wheels (depending on the position of the lifting gear / attachment on the mobile work machine) to lose contact with the ground. This makes the mobile work machine temporarily unsteerable.
[0005] It is known to use the attachment for vibration damping by actively operating the lifting gear. Such a procedure is known, for example, from document DE 10 2018 209 073 A1. However, such a procedure requires special measures for monitoring any vibrations that occur.
[0006] It is also known to use bladder accumulators on hydraulic lines for vibration damping. These bladder accumulators can absorb and / or release volumes of hydraulic fluid from hydraulic cylinders for vibration damping. Such bladder accumulators are known, for example, from EP 3 513 640 B1. Such bladder accumulators require additional equipment.
[0007] Based on this, a particularly efficient method for vibration damping of mobile work machines, hoists and attachments is presented here, which requires little additional equipment and few additional sensors for vibration detection / dampening and which at the same time enables efficient vibration damping.
[0008] This object is achieved by the invention according to the features of the independent patent claims. Further advantageous embodiments are specified in the dependent claims as well as in the description and, in particular, in the description of the figures. It should be noted that the person skilled in the art can combine the individual features in a technologically expedient manner and thus arrive at further embodiments of the invention.
[0009] The invention relates to a method for damping vibrations caused by an attachment on a mobile work machine during operation and in particular during travel, wherein the attachment can be moved using a hydraulically actuated lifting gear, wherein the hydraulic lifting gear has at least one hydraulic working cylinder which can be controlled by at least one controllable hydraulic valve, wherein the controllable hydraulic valve can be actuated to supply the hydraulic working cylinder with hydraulic fluid and to move the lifting gear, comprising at least the following steps: a) determining at least one target pressure value in at least one chamber and / or a pressure line of the hydraulic working cylinder for maintaining a predetermined position of the lifting gear; b) monitoring at least one actual pressure value in the at least one chamber and / or a pressure line of the hydraulic working cylinder;c) Determining at least one controlled variable that is representative of a difference between an actual pressure value and a target pressure value; d) Determining a control signal for the controllable hydraulic valve based on the controlled variable and controlling the hydraulic valve with the control signal in order to regulate the actual pressure value to the target pressure value.
[0010] Hoists used to apply the method described here have multiple degrees of freedom. Hoists with multiple degrees of freedom are generally preferred. A degree of freedom describes the mobility of the hoist around a predetermined pivot point, which forms a moment center in steps a) and b). Typical hoists used to apply the method described here have, for example, a main arm that can be raised and / or lowered using a hydraulic working cylinder arrangement, as well as a tilting mechanism with which the attachment (e.g., a bucket or fork) can be tilted.
[0011] Typically, such a hoist has a working cylinder arrangement, which can also be referred to as the main working cylinder arrangement, with which the entire hoist can be raised and / or lowered. Preferably, the working cylinder or working cylinder arrangement operated with the method described here is this main working cylinder arrangement, with which the entire hoist can be raised and / or lowered.
[0012] The method can be applied in particular to lifting gear used on typical mobile work machines, for example tractors. The invention and the method according to the invention are particularly intended for attachments and lifting gear that are detachably attached to a mobile work machine. Such lifting gear and attachments are particularly common on tractors as mobile work machines. However, the invention is fundamentally applicable to vibration damping on all types of attachments attached to a mobile work machine that are movable via hydraulics. The terms "lifting gear" and "attachment" are to be understood broadly. For the invention to be applicable, it is not necessary for the lifting gear or attachment to be detachable from the mobile work machine.
[0013] In the method described here, a pressure in a chamber of a hydraulic working cylinder and / or in a pressure line supplying a hydraulic working cylinder with pressurised hydraulic fluid is used as the controlled variable for vibration dampening (see steps a), b) and c)). Vibrations of the lifting gear and the attachment usually result in pressure fluctuations in the chambers of the hydraulic working cylinders and / or in the pressure lines supplying hydraulic working cylinders with pressurised hydraulic fluid. By controlling an actual pressure to a target pressure as described here, such pressure fluctuations can be reduced. It has been found that this also enables an efficient reduction of vibrations of the lifting gear and / or the attachment.
[0014] Particularly in the case of mobile work machines, such as off-road tractors, particularly complex excitations occur during use, which lead to significant vibrations in lifting gear and attachments. Such vibration excitations occur to a significant extent during road travel but also during field work. During road travel, the vehicle's vibrations can lead to loss of control, which significantly impacts driving safety. Likewise, the vehicle's vibrations during work processes noticeably influence driving comfort as well as working speed. In principle, the possible operating situations and excitations that lead to problematic vibrations in lifting gear and attachments are therefore very diverse. According to the present method, a pressure in a chamber and / or pressure line of a hydraulic working cylinder is used as the controlled variable for vibration compensation.It has been found that this is a very effective way to detect and reduce various types of vibrations that can occur in very different operating situations of the mobile machine.
[0015] Additional sensors for detecting vibrations, such as force measuring bolts, position sensors, optical sensors, etc., can be dispensed with to carry out the described procedure.
[0016] According to step d), based on the controlled variable determined in step c), a control signal is generated for a controllable hydraulic valve, with which the working cylinder is controlled to actuate the lifting gear.
[0017] Preferably, the described method steps a), b), c) and d) are each carried out continuously and in parallel to one another during operation of the mobile work machine, with target pressure values and actual pressure values being continuously monitored (steps a) and b)) and then, also continuously, for example with a regular repetition frequency, control variables and control signals according to steps c) and d) being generated and applied. The described method is preferably carried out using an electronic or digital control unit which, to carry out the method, is operated at a repetition frequency which can be between 10 Hz and 10,000 Hz, for example. The repetition frequency of the steps of the described method is preferably set appropriately depending on the frequency range in which vibrations of the attachment and the lifting gear can occur.
[0018] Such hydraulic valves typically have a P-port, to which a supply pressure is applied, and a T-port, which is connected to a return line or a tank for hydraulic fluid. By adjusting the valve spool, the P-port can be connected either to a port A (A-port) or a port B (B-port), so that hydraulic fluid is then supplied from the P-port to the respective port A or B. The other port B or A is then connected to the T-port, so that the hydraulic fluid can flow from the port into the return line or back into a tank.
[0019] The valve drive of such hydraulic valves is preferably carried out with an electric motor (for example a stepper motor or a BLCD motor (BLCD = brushless direct current), which actuates a valve spool of the hydraulic valve. The valve spool and the motor are usually coupled to one another by a gear. The gear can be designed as either a single-stage or multi-stage gear. For example, a single-stage gear usually comprises at least one rack on the valve spool and a gear on the motor, whereby the motor drives the rack on the valve spool with the gear and a rotary movement on the stepper motor is converted into a linear movement on the rack / on the valve spool.
[0020] The control signal determined in step d), which is used to control the controllable hydraulic valve to regulate the pressure, is preferably a control signal for such a valve drive. When reference is made here to control signals for the hydraulic valve, this typically refers to control signals that act on the drive of the hydraulic valve.
[0021] The described method is particularly advantageous if the target pressure value is adjusted during the execution of the method in order to take into account working movements and / or changes in the position of the hoist and / or changes and shifts in the load of the hoist.
[0022] The described method is particularly preferred if the actual pressure value is monitored in step c) in such a way that vibrations of the hoisting gear are detected. Vibrations occurring in hoists and / or attachments usually always lie within a specific frequency range. This frequency range is significantly influenced by the design of the hoisting gear and the attachment, as well as by the load transported by the attachment. The method described here is preferably implemented such that target pressure values and actual pressure values are preferably processed with a bandpass filter before they are used to determine controlled variables and / or control signals (steps c) and d)).
[0023] In particular, long-term changes in target pressure values are preferably ignored when implementing the method. In other words, long-term changes in the target pressure values that are not due to oscillations are preferably detected and determined. Preferably, the target pressure value specification used for the described method is regularly adjusted according to step a) so that the actual pressure values detected in step b) are always regulated to the desired, correct target pressure value.
[0024] Such long-term changes in target pressure values can occur, for example, because the position of the mobile work machine has changed, and thus the pressure in the working cylinders required to hold a load has changed. Such an effect can occur, for example, if the gradient of a road on which the mobile work machine is traveling changes. Such long-term changes can also occur, for example, because the weight of a load changes, for example, because another mobile work machine adds additional load to the attachment during a journey.
[0025] In order to maintain the intended, desired operation of a mobile work machine under such changing conditions, an adjustment of the target pressure value is particularly necessary. This can be achieved, for example, by filtering an actual pressure monitored according to step b) with a high-pass filter and determining the controlled variable according to step b) using the high-pass filtered actual pressure value. Preferably, the actual pressure is also filtered with a low-pass filter at the same time. In preferred embodiments, the low-pass filtered actual pressure value is used to adjust a target pressure value.
[0026] However, it is also possible for target pressure values to be adjusted in another way, for example by a higher-level control system detecting reasons for a change in the target pressure value and a control unit calculating an adjustment of the target pressure values, which is then used for the described process.
[0027] The method is particularly preferred if the execution of method steps a) to d) is suppressed in a first operating mode of the mobile work machine and wherein the mobile work machine can be brought into a second operating mode by an operator in which the execution of method steps a) to d) takes place permanently in the manner of a damping control in order to dampen vibrations caused by a mobile attachment.
[0028] The damping of vibrations of mobile attachments or lifting gear proposed according to the described method is particularly suitable for certain operating situations of the mobile attachment, for example, the road travel of the mobile work machine described above. In other operating situations, implementing the described method could potentially negatively impact and even hinder work with the mobile work machine. It is therefore advantageous if the described method is only activated in certain operating modes (here, the second operating mode) and suppressed in other operating modes (here, the first operating mode).
[0029] In the procedure proposed here, an operator can manually select whether the first operating mode or the second operating mode is activated. Depending on the design of the second operating mode, the controller can independently detect when further control signals, e.g. from the operator, are received and, in these situations, interrupt the execution of the described method so that the user control is processed with priority and transferred to the hydraulic valve. Preferably, the controller can then independently switch back to the second operating mode. Preferably, control signals from an operator in the first operating mode are transferred directly as control signals to the controllable hydraulic valve.
[0030] In a preferred embodiment of the described method, the execution of method steps a) to d) is suppressed in a first operating mode of the mobile work machine, wherein the mobile work machine is configured such that, when predetermined boundary conditions are present, it automatically switches to a second operating mode in which the execution of method steps a) to d) takes place permanently in the manner of a damping control in order to dampen vibrations caused by a mobile attachment.
[0031] Here, an automatic switch from a first operating mode to a second operating mode is proposed. One boundary condition that can be used as a criterion for such an automatic switch of operating mode is, for example, the driving speed of the mobile work machine. If the driving speed is high, vibration damping is required, and then the second operating mode can be switched to automatically. When the driving speed decreases again, a switch back to the first operating mode can also occur automatically.
[0032] In preferred embodiments of the method and mobile work machines, both an automatic change and a manual change from the first operating mode to the second operating mode and back are provided.
[0033] The described method is particularly advantageous if the hydraulic valve has an electric drive which actuates a valve spool for opening and closing hydraulic channels in the hydraulic valve, wherein the hydraulic valve has no hydraulic pilot control.
[0034] Hydraulic valves are known in which a valve spool is moved with the assistance of a hydraulic pilot control to selectively connect the ports A and B (described above) to the ports P and T. Such hydraulic valves are generally advantageous because relatively small control forces are required to drive the pilot control. For the method described here, however, valves are preferably used which do not have such a hydraulic pilot control, but which have a relatively powerful electric valve drive which acts on the valve spool without additional hydraulic support. The drive of such valves preferably comprises a stepper motor and, particularly preferably, such a drive further comprises an electric pre-stage which enables very rapid conversion of control signals into drive currents for driving the stepper motor.
[0035] Such hydraulic valves, in particular, exhibit a lower delay response than hydraulic valves with hydraulic pilot control. For this reason, they are advantageous for implementing the described method. In the described method, pressure fluctuations in the actual pressure should be regulated as accurately as possible to the target pressure value. To achieve this, a fast response of the hydraulic valve with as little delay as possible is advantageous. Such a response can be achieved with the described hydraulic valves without pilot control.
[0036] The method can also be used for mobile work machines with hoists or attachments that have controllable hydraulic valves with hydraulic pilot control for controlling working cylinders. Depending on the design, such hydraulic valves can also have a sufficiently low deceleration behavior for carrying out the described method. It is also advantageous if the working cylinder is a double-acting cylinder with a first chamber and a second chamber, wherein in step a) a target pressure value is determined for each chamber, and wherein, according to steps b) to d), an actual pressure value is regulated to the corresponding target pressure value for both chambers.
[0037] In most applications, the method is used when a lifting gear or an attachment attached to a lifting gear is carrying a load. The pressure in one chamber of such working cylinders is usually then significantly increased and it is sufficient to use the described method to determine pressures for only this chamber and to regulate them according to steps a) to d). Such embodiments are included here. However, the described embodiments of the described method with double-acting cylinders are also preferred, in which a working piston of a working cylinder is clamped between two chambers. A target pressure value can then be determined for both chambers according to step a), with actual pressure values also being determined for both chambers according to step b).Preferably, control variables are first determined for both chambers according to step c), which are then particularly preferably processed in step d) into a common control signal. The control signal or the actuation of the hydraulic valve as a result of the control signal according to step d) typically affects both chambers of such a double-acting cylinder. If a port A in the hydraulic valve connected to a first chamber is connected to the pressure port P, a connection between port B and the tank port is normally established at the same time.
[0038] The use of pressure from both chambers of double-acting hydraulic cylinders enables particularly precise operation of the described process.
[0039] It is further particularly advantageous if the working cylinder is a differential cylinder having a first chamber on a base side and a second chamber on a rod side, wherein a cross section of the first chamber is larger than a cross section of the second chamber.
[0040] Preferably, the different chamber cross-sections of the first chamber and the second chamber are taken into account in particular when determining the controlled variable(s) in step c) and / or when determining the control signal in step d).
[0041] The method is also applicable if the working cylinders, or at least one working cylinder, is a double-acting cylinder. In principle, the described method is preferably used for work machines, hoists, or attachments that have double-acting working cylinders. However, the working cylinders do not have to be differential cylinders. The use of double-acting working cylinders is generally very advantageous for implementing the described method because double-acting working cylinders can be driven in both directions of movement using controllable hydraulic valves, thus simplifying the damping of vibrations. Furthermore, pressure sensors can be used to receive pressure signals from both chambers of double-acting working cylinders, which can then be used to implement the described method.
[0042] The method is also preferred if chambers of the working cylinder are connected to the at least one hydraulic valve via pressure lines, wherein pressure sensors for determining the actual pressure value are arranged on the pressure lines and at a distance from the chambers of the working cylinder.
[0043] Particularly preferably, the distance between a pressure sensor for determining the actual pressure value according to step b) and an inlet of a chamber of the working cylinder along a pressure line is at least 50 cm [centimeters]. Longer distances are permissible, and the implementation of the described method is preferably not impaired by longer distances. As a result, vibrations of the lifting gear and the attachment generate forces on the hydraulic working cylinders of the lifting gear. These forces generate pressure in the working cylinders. To compensate for vibrations of the lifting gear and the attachment, it is necessary to control the pressure in the working cylinders such that the working cylinders generate vibrations that counteract the forces.
[0044] It has been found that along (usual) pressure lines, the pressure in the working cylinders is transmitted to pressure sensors, even over longer pressure lines, in such a way that the actual pressure values measured there are sufficient for the successful implementation of the described process.
[0045] The described method is particularly advantageous if pressure sensors for determining the actual pressure value are arranged at connection points of the pressure lines on the hydraulic valve.
[0046] Common mobile work machines have a block of hydraulic valves mounted in a (possibly protected) position on the mobile work machine. If the lifting gear with the attachment is removably mounted on the mobile work machine, the block with the hydraulic valves is preferably still permanently mounted on the mobile work machine. When mounting the lifting gear on the mobile work machine, the hydraulic lines of the lifting gear are then preferably connected to the designated connections on the hydraulic block on the mobile work machine.
[0047] If the hydraulic valve has two ports (for example, ports A and B as described above), then pressure sensors are preferably also present at both ports, with which actual pressure values can be determined. Particularly preferably, the pressure sensors can then be considered together as part of a pressure sensor arrangement with which multiple pressure values can be determined. If the hydraulic valve has two ports (for example, ports A and B as described above), then two connection points for hydraulic lines are also preferably present.
[0048] Such a block of hydraulic valves is typically a power splitter (particularly a load-sensing circuit) with which pressurized hydraulic fluid provided by a central hydraulic fluid supply can be specifically made available to individual consumers (particularly individual hydraulic working cylinders or arrangements with multiple hydraulic working cylinders). The hydraulic valve used for the method described here is preferably part of such a load-sensing circuit.
[0049] It is particularly advantageous if the hydraulic valve (and possibly also other hydraulic valves) of the mobile work machine are provided with connections to which hydraulic lines of a lifting gear can be connected to ports A and B of the hydraulic valve. This connects the hydraulic valve to the working cylinder of the lifting gear, with which the described method can be carried out. Pressure sensors for determining the actual pressure values are preferably arranged at these connection points in such a way that they remain with the hydraulic valve when hydraulic lines are disconnected from the hydraulic valve. All components used to operate the described method can then remain together with the hydraulic valve.The working cylinders of the hoist, in which the pressure in the vibration damping chambers is regulated according to the described method, are connected to the pressure sensors and the hydraulic valve via the hydraulic lines. No additional sensors are required when the hoist is mounted on the mobile machine. In particular, no additional connection work is required. It is particularly preferred if no vibration damping components are installed on the working cylinder and / or pressure lines connecting the working cylinder to the hydraulic valve.
[0050] In particular, the application of the described method eliminates the need for additional active and / or passive components for vibration damping. Only a hydraulic valve, which is already required for the operation of the hoist, is required for the operation of the described method. Such hydraulic valves have previously only been used for the active control of working cylinders. Here, it is proposed to use these hydraulic valves additionally, and preferably alternatively, for vibration damping. To implement vibration damping with a directional control valve in the working hydraulics, a control and regulation strategy is used that is capable of damping vibrations through the controlled control of a hydraulic valve and the system design.
[0051] In particular, additional compensation volumes on the hydraulic lines can be dispensed with.
[0052] Also to be described here is a control unit for a mobile work machine with an attachment which is designed to carry out the described method.
[0053] The control device is particularly preferred if it is configured to receive an activation signal in order to activate the damping of vibrations according to the described method.
[0054] Also described here is a mobile work machine with a lifting gear, wherein an attachment can be attached to the mobile work machine and is movable by means of the lifting gear, and wherein the mobile work machine has a described control unit and is particularly preferably configured to be operated according to the described method. It should be noted that the particular advantages and design features described in connection with the method described above are also applicable and transferable to the control unit and the described mobile work machine described below.
[0055] It is particularly preferred if the mobile work machine has a hydraulic block containing a hydraulic valve that can be operated together with the other components (in particular together with a lifting gear and / or an attachment) according to the described method. It is particularly preferred if the hydraulic block is a load-sensing block, with a hydraulic valve of this block particularly preferably being configured to be operable according to the described method.
[0056] It is further preferred if the pressure sensors or a pressure sensor arrangement for carrying out the described method are permanently connected to the hydraulic valve or the hydraulic block. Particularly preferably, all components for operating the described method are installed on the mobile work machine. Particularly preferably, the lifting gear is interchangeably mounted on the mobile work machine, wherein hydraulic lines of the lifting gear can be connected to a valve permanently installed on the mobile work machine in order to configure the combination of mobile work machine and lifting gear or attachment for operation according to the method described here.
[0057] The invention and the technical context of the invention are explained in more detail below with reference to the figures. The figures show preferred embodiments to which the invention is not limited. It should be noted in particular that the figures, and in particular the proportions depicted in the figures, are only schematic. They show:
[0058] Fig. 1 : a mobile work machine with a lifting gear with attachment;
[0059] Fig. 2: a hydraulic system for carrying out a described method; Fig. 3: an overall hydraulic system of a mobile work machine with lifting gear and attachment; and
[0060] Fig. 4: a schematic flow diagram of the described method.
[0061] Figure 1 shows a mobile work machine 2 with a lifting gear 3 and an attachment 1. The attachment 1 here is a bucket, which can be used to pick up bulk material as a load. The attachment 1 can also be another attachment 1, such as a fork with which bales can be picked up. The lifting gear 3 has hydraulic working cylinders 4 with which the lifting gear 3 can be operated.
[0062] The hoist 3 with the attachment 1 and any load carried in the attachment 1 forms a system that can vibrate. This is particularly true when the mobile work machine 2 is in motion. For example, a situation in which the mobile work machine 2 is traveling on the road is particularly critical for the generation of vibrations because, for example, bumps in the road can excite the mobile work machine 1, causing the system consisting of the mobile work machine 2, hoist 3, attachment 1, and possibly the load to vibrate. Such vibrations can be efficiently dampened using the system described in more detail here and with reference to the following figures.
[0063] Fig. 2 shows a hydraulic system 26 that can be used on the mobile work machine 2 for carrying out the described method. The hydraulic system 26 shown in Fig. 2 is preferably part of an overall hydraulic system of the mobile work machine 2. The hydraulic system 26 has two working cylinders 4 that are connected in parallel to one another by a distributor 21, thus forming a working cylinder arrangement that can, for example, raise or lower a lifting gear 3 as a whole. The working cylinders 4 are each differential cylinders with a chamber 6 on a base side 15 and with a chamber 6 on a rod side 16, and a working piston 28 arranged between them, which can be moved by pressurizing the chambers 6 with hydraulic fluid.
[0064] The working cylinders 4 and their chambers 6 are connected via pressure lines 7 to the hydraulic valve 5 and to connection points 18 of the hydraulic valve 5. The hydraulic valve 5 preferably has a valve spool 13, shown schematically here, which can be moved into different positions. Depending on the position of the valve spool 13, the hydraulic valve 5 opens different hydraulic channels 14, so that connections of the hydraulic valve 5 are connected to one another differently depending on the position of the valve spool 13. Preferably, the two pressure lines 7 to the working cylinders 4 are connected to connections A and B of the hydraulic valve 5, which, depending on the position of the valve spool 13, can be optionally connected to connection P, wherein the other connection B or A is then connected to connection T.A hydraulic fluid supply 20 provides pressurized hydraulic fluid at port P and preferably receives hydraulic fluid at port T.
[0065] Pressure sensors 17 are arranged at each of the connection points 18 of the hydraulic valve 5, with which the pressure in the pressure lines 7 can be monitored. The pressure sensors 17 preferably together form a pressure sensor arrangement 23. The pressure determined by the pressure sensors 17 is preferably fed as the actual pressure value 9 to a control unit 19 shown here. A target pressure value 8 is preferably specified in the control unit 19. A controlled variable 10 is preferably formed in the control unit 19, which can be formed, for example, as the difference between the actual pressure value 9 and the target pressure value 8. This controlled variable 10 is preferably used to form a control signal 11, with which an electric drive 12 of the hydraulic valve 5 can be actuated in order to actuate the hydraulic valve 5 to regulate the actual pressure value 9 to the target pressure value 8.
[0066] It is schematically indicated here that the hydraulic valve 5 can also be controlled with regular control signals 24 in order to control the lifting gear 3. For example, an activation circuit 25 can be used to switch between a first operating mode and a second operating mode. In the first operating mode, for example, regular control signals 24 are used to directly control the lifting gear 3 or the working cylinder 4. In the second operating mode, the lifting gear 3 or the working cylinder 4 is preferably controlled by the control unit 19 or with the aid of the described method. Regular control signals 24 can, for example, specify target pressure values 8 for the described method as a target value supply 29.
[0067] Fig. 3 now shows an overall hydraulic system 27 of a mobile work machine 2 with a lifting gear 3 and an attachment 1. The hydraulic system 26 described in Fig. 2 for carrying out the described method forms part of this overall hydraulic system 27. The overall hydraulic system 27 preferably has a hydraulic block with a plurality of hydraulic valves 5 for various hydraulic functions. One of these hydraulic valves 5 is the hydraulic valve 5, which, together with the working cylinders 4 connected to it, forms the hydraulic system 26, as shown in Fig. 2 and as used to carry out the described method.
[0068] Other hydraulic valves 5 of the hydraulic block are provided for other functions, for example for controlling working cylinders 4 for tipping an attachment 1 or for opening and closing a locking mechanism for attachments on the lifting gear 3.
[0069] The hydraulic block with the plurality of hydraulic valves 5 preferably forms a load-sensing circuit 22, with which hydraulic fluid provided by a hydraulic fluid supply 20 can be distributed to various consumers via the hydraulic valves 5.
[0070] Figure 4 shows a schematic flow diagram of the described method. It shows the method steps a), b), c), and d), which are preferably repeated continuously or take place in parallel in order to dampen vibrations of an attachment 1. Reference symbols
[0071] 1 attachment
[0072] 2 mobile work machines
[0073] 3 lifting gear
[0074] 4 working cylinders
[0075] 5 Hydraulic valve
[0076] 6 chamber
[0077] 7 Pressure line
[0078] 8 Target pressure value
[0079] 9 Actual pressure value
[0080] 10 Control variable
[0081] 11 Control signal
[0082] 12 electric drive
[0083] 13 valve slides
[0084] 14 hydraulic channels
[0085] 15 Bottom side
[0086] 16 rod side
[0087] 17 Pressure sensor
[0088] 18 Junction
[0089] 19 Control unit
[0090] 20 Hydraulic fluid supply
[0091] 21 Distribution
[0092] 22 Load-sensing circuit
[0093] 23 Pressure sensor arrangement
[0094] 24 regular control signal
[0095] 25 Activation circuit
[0096] 26 Hydraulic system
[0097] 27 Complete hydraulic system
[0098] 28 working pistons
[0099] 29 Setpoint supply
Claims
Claims 1. A method for damping vibrations caused by an attachment (1) on a mobile work machine (2) during operation thereof and in particular during travel, wherein the attachment (1) is movable by means of a hydraulically actuated lifting gear (3), wherein the hydraulic lifting gear (3) has at least one hydraulic working cylinder (4) which can be controlled by at least one controllable hydraulic valve (5), wherein the controllable hydraulic valve (5) can be actuated in order to supply the hydraulic working cylinder (4) with hydraulic fluid and to move the lifting gear (3), comprising at least the following steps: a) determining at least one target pressure value (8) in at least one chamber (6) and / or a pressure line (7) of the hydraulic working cylinder (4) for maintaining a predetermined position of the lifting gear (3);b) Monitoring at least one actual pressure value (9) in the at least one chamber (6) and / or a pressure line (7) of the hydraulic working cylinder (4); c) Determining at least one controlled variable (10) that is representative of a difference between an actual pressure value (9) and a target pressure value (8); d) Determining a control signal (11) for the controllable hydraulic valve (5) based on the controlled variable (10) and controlling the hydraulic valve (5) with the control signal (11) in order to regulate the actual pressure value (9) to the target pressure value (8); 2. Method according to claim 1, wherein the target pressure value (8) is adjusted during the execution of the method in order to take into account working movements and / or changes in the position of the lifting gear (3) and / or changes and shifts in the load of the lifting gear (3).
3. Method according to one of the preceding claims, wherein the actual pressure value (9) is monitored in step c) such that vibrations of the lifting gear (3) are detected.
4. Method according to one of the preceding claims, wherein the execution of method steps a) to d) is suppressed in a first operating mode of the mobile work machine (2) and wherein the mobile work machine (2) can be brought by an operator into a second operating mode in which the execution of method steps a) to d) takes place permanently in the manner of a damping control in order to dampen vibrations caused by a mobile attachment (1).
5. Method according to one of the preceding claims, wherein the execution of method steps a) to d) is suppressed in a first operating mode of the mobile work machine (2) and wherein the mobile work machine (2) is set up in such a way that, when predetermined boundary conditions are present, it automatically changes to a second operating mode in which the execution of method steps a) to d) takes place permanently in the manner of a damping control in order to dampen vibrations caused by a mobile attachment (1).
6. Method according to one of the preceding claims, wherein the hydraulic valve (5) has an electric drive (12) which actuates a valve slide (13) for opening and closing hydraulic channels (14) in the hydraulic valve (5), wherein the hydraulic valve (5) has no hydraulic pilot control.
7. Method according to one of the preceding claims, wherein the working cylinder (4) is a double-acting cylinder with a first chamber (6) and with a second chamber (6), wherein in step a) a target pressure value (8) is determined for each chamber (6), and wherein according to the steps b) to d) for both chambers (6) an actual pressure value (9) is regulated to the corresponding target pressure value (8).
8. The method according to claim 3, wherein the working cylinder (4) is a differential cylinder having a first chamber (6) on a bottom side (15) and a second chamber (6) on a rod side (16), wherein a cross section of the first chamber (6) is larger than a cross section of the second chamber (6).
9. Method according to one of the preceding claims, wherein chambers (6) of the working cylinder (4) are connected to the at least one hydraulic valve (5) via pressure lines (7), wherein pressure sensors (17) for determining the actual pressure value (9) are arranged on the pressure lines (7) and at a distance from the chambers (6) of the working cylinder (4).
10. The method according to claim 5, wherein pressure sensors (17) for determining the actual pressure value (9) are arranged at connection points (18) of the pressure lines (7) on the hydraulic valve (5).
11. Method according to one of the preceding claims, wherein no components for vibration damping are installed on the working cylinder (4) and / or on pressure lines (7) connecting the working cylinder (4) to the hydraulic valve (5).
12. Control device (19) for a mobile work machine (2) with an attachment (1), which is designed to carry out the method according to one of the preceding claims.
13. Control device (19) according to claim 8, which is arranged to receive an activation signal in order to activate the damping of vibrations according to the described method.
14. Mobile working machine (2) with a lifting gear (3), wherein an attachment (1) can be attached to the mobile working machine (2), which attachment can be moved by means of the Hoist (3) is movable and wherein the mobile work machine (2) has a control device (19) according to claim 13;