Actuating device for at least one fluid-operable consumer device

Abstract

An actuation device for at least one fluid-operable consumer 10, such as a hydraulic actuator, is disclosed, which comprises at least one valve control device V1 for controlling the alternating operation of the respective consumer 10, and at least one suspension device 14 connected between the valve control device V1 and the respective consumer 10, the suspension device 14 having a further valve control device V2, whose valve piston 20 is infinitely movable in a corresponding valve housing, characterized in that in the actuation device, in a suspension position V2.V of the valve piston 20 of the further valve control device V2, an accumulator 16 of the suspension device 14 is connected to the respective consumer 10 via a fluid path through the further valve control device V2. Furthermore, a method for actuating the respective consumer 10 by means of such an actuation device is disclosed.

Description

[Technical field]

[0001] The present invention relates to an actuation device for at least one fluid-operable consumer device, such as a hydraulic actuator, which comprises at least one valve control device for controlling the alternating operation of the respective consumer device and at least one suspension device connected between the valve control device and the respective consumer device, the suspension device having a further valve control device, whose valve piston is infinitely movable in a corresponding valve housing. [Background technology]

[0002] From DE 10 2014 000 696 A1 a device for a consumer appliance in the form of a hydraulically actuated actuator is known, which has as a control device a working hydraulic system via which two working chambers of the actuator can be alternately pressurized with hydraulic fluid. A valve device of the device is connected to such a fluid path as part of a suspension device, which in addition to a changeover valve and three logic elements comprises a further control device in the form of a proportional control valve.

[0003] The actuator can be connected by a valve device to an accumulator, which is another part of the suspension device, before the trapped pressure in the accumulator is discharged via a control valve towards a tank until the trapped pressure reaches the working pressure, if the trapped pressure in the accumulator is higher than the working pressure in the actuator. During operation of the device, a changeover valve is used to establish or cut off a fluid connection for charging the accumulator. A first logic element is used to compare the working pressure with the trapped pressure in order to operate control lines for operating the second and third logic elements. The second logic element is used to establish or cut off a fluid connection between the working chamber of the actuator and the accumulator, and the third logic element is used to establish or cut off a fluid connection between the other working chamber of the actuator and the tank. When the device is operated in a spring-damper mode, where the trapped pressure is adapted to the working pressure, the accumulator is connected to the actuator via a fluid path through the second logic element. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] DE 102014000696 Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to provide an actuating device for at least one fluid-operable consumer appliance, which is of simple construction and has improved operational reliability. [Means for solving the problem]

[0006] The above object is achieved by an actuating device according to the invention, which generally has the features of patent claim 1.

[0007] According to the characterizing feature of claim 1, the actuating device according to the invention is characterized in that in a suspension position of the valve piston of the further valve control device, an accumulator of the suspension device is connected to the respective consumer via a fluid path through the further valve control device.

[0008] This allows the actuation device to be simply designed in terms of its structure. The logic elements provided in the prior art according to DE 10 200 03 133 A1, as well as the switching and control valves, are not necessary or are replaced according to the invention by a suspension device with only one valve in its simple embodiment. Due to the reduced number of valves and therefore also the reduced number of fluid lines and fluid connections, leakages in the suspension device are reduced, which is advantageous in lifting mechanism suspension systems in which the actuation device is preferably used, since the lowering of the lifting mechanism due to leakages during operation of the lifting mechanism suspension system is reduced. This increases the operational reliability of the actuation device. Furthermore, the reduced number of valves in the suspension device improves the dynamics of the actuation device and reduces the manufacturing costs.

[0009] In a particularly preferred embodiment, the actuator is used for the fluid pressure matching of the charging pressure of the accumulator with the suspension pressure for holding the load in the consumer. Particularly preferred is a valve control device arranged in the main fluid branch and a suspension device arranged in the secondary fluid branch, which are connected in parallel to each other and arranged between the pressure supply connection and the consumer. Here, the consumer can be designed as an actuator, such as a hydraulically driven motor or a hydraulically driven cylinder.

[0010] In another preferred embodiment, the further valve control device is adapted such that, when operated accordingly, the suspension pressure in the consumer and the filling pressure of the accumulator are gradually equalized via the further valve control device and are accordingly adapted to each other. Preferably, the further valve control device here is adapted such that, when its valve piston moves to the suspension position, the fluid path is at least partially formed in a gradually increasing manner, and at the same time, the suspension pressure in the consumer and the filling pressure of the accumulator are equalized via the fluid path and are accordingly adapted to each other more and more. By establishing such a fluid connection, the accumulator is connected and the suspension is thereby activated. If there are different fluid pressures in the consumer and in the accumulator, the piston rod of the consumer moves after the initial establishment of this fluid connection, but this does not move abruptly but in a controlled, gradual manner due to the gradually increasing formation of the fluid path. This allows the operator of the actuating device to intervene and influence the movement of the piston rod. Furthermore, abrupt movements of the piston rod of the consumer are prevented when the suspension is activated. Sudden movements, if an actuating device is used in the consumer equipment in the form of an actuating cylinder of the lifting mechanism suspension system, can have a detrimental effect on the running stability of the working machine and can lead to loss or damage of the load lifted by the lifting mechanism.

[0011] In another preferred embodiment, the valve piston is adapted to separate the pressure supply connection of the actuator and the accumulator from each other during the incremental formation of the fluid path and / or when placed in the suspension position, thereby preventing the piston rod of the consumer from moving due to the fluid pressure at the pressure supply connection differing from the suspension pressure holding the load in the consumer during suspension actuation.

[0012] In another preferred embodiment, for operating the further valve control device, an actuating device for the valve piston of the further valve control device is provided, by means of which a force can be applied to the control side of the valve piston of the further valve control device. Preferably, this actuating device is designed as a proportional pressure control valve, via which a control fluid pressure can be applied to the control side of the valve piston of the further valve control device. Preferably, the proportional pressure control valve is electromagnetically actuable against the force of the control fluid pressure. Alternatively, for operating the valve piston of the further valve control device, an electromagnetic actuator can be provided which acts on one control side of the valve piston of the further valve control device. In this way, only one electrical control line needs to be provided for operating the respective suspension device, in particular the further valve control device.

[0013] In another preferred embodiment, a control unit is provided, connected to it with at least one input device and preferably at least one sensor device for detecting state values, such that the proportional pressure control valve or actuator can be controlled by the control unit.

[0014] In another preferred embodiment, the valve piston of the further valve control device can be arranged in a filling position in which the accumulator is connected to a pressure supply connection via a further fluid path through the further valve control device for filling it, and preferably the consumers are each connected to this pressure supply connection via a valve control device, so that the accumulator can be filled every time a pump boost control command for advancing or retracting the piston rod of the consumer is issued, in particular with an adjustable, preferably proportionally adjustable orifice or throttle connected to the subsequent fluid path.

[0015] In another preferred embodiment, the valve piston of the further valve control device can be arranged in a discharge position in which the accumulator is connected to the tank connection via another fluid path through the further valve control device, so that the accumulator can be emptied to the tank so that the fluid pressure or energy in the accumulator does not remain under pressure when the actuator is in a stationary state. In particular, it is preferred that an orifice or throttle is arranged in this fluid path.

[0016] In another preferred embodiment, the valve piston of the further valve control device can be arranged in at least one isolation position, which isolates all connections of this further valve control device from one another, such that an isolation position is provided between the abovementioned suspension position and the filling position and / or another isolation position is provided between the filling position and the discharge position. The isolation position forms a waiting position into which the valve piston can be placed when a previous method step of the actuation device has been completed and the actuation device is ready for a subsequent method step, thereby improving the response behavior of the actuation device.

[0017] In another preferred embodiment, the consumer is connected to the tank connection at the suspension position of the further valve control device, in particular via the further valve control device.As an alternative, a drain valve can be provided in the fluid connection between the consumer and the tank connection, and a control fluid pressure acts on the control side of the valve piston to operate this drain valve.

[0018] In another preferred embodiment, in the fluid connection between the consumer and the further valve control device and / or between the further valve control device and the accumulator, a pressure sensor detects the load-holding suspension pressure or the charge pressure, each of which is connected to a control unit of the actuator for transmitting its pressure measurement value. As a result, even before the connection between the accumulator and the actuator is established, the charge pressure of the accumulator can be actively adapted automatically by the control unit to the load-holding suspension pressure of the consumer, so that during suspension actuation, movement of the piston rod of the consumer is minimized or even prevented. Moreover, the filling speed of the accumulator can be adjusted based on the measurement value of the pressure sensor assigned to the accumulator.

[0019] In another preferred embodiment, a load-keeping valve is provided in the line connected to the consumer, which can be operated with the control fluid pressure by a proportional valve or via an additional connection of an actuator or by a control unit. If the load-keeping valve is operated with the control fluid pressure, a separate operation of the load-keeping valve is not necessary, so that no components required for such a separate operation need to be provided. If the load-keeping valve is controlled by the control unit, this can be done directly or indirectly via the control valve.

[0020] In another preferred embodiment, a pressure source connectable to the pressure supply connection can be controlled by a load sensing signal that is dependent on the charge pressure, and can thus be adjusted as a function of the fluid pressure in the accumulator during the accumulator filling process.

[0021] In other preferred embodiments, the alternative valve control device is designed as a 3 / 3 or 5 / 3 or 6 / 5 proportional directional control valve in a spool configuration.

[0022] In another preferred embodiment, the fluid used is a hydraulic fluid, in particular a hydraulic oil, so that all fluid components of the actuating device are hydraulic components.

[0023] In another preferred embodiment, a pressure relief valve is provided between the pressure supply connection and the further valve control device and / or between the further valve control device and the accumulator to limit the system pressure.

[0024] In another preferred embodiment, a mobile work machine, in particular a construction machine such as a wheel loader or a mobile excavator, is provided which comprises a lifting mechanism having at least one consumer and an actuation device as described above capable of actuating the respective consumer.

[0025] The subject of the invention is further a method for operating at least one fluid-operable consumer by means of an actuation device as described above, comprising the following method steps: filling the accumulator to an initial charge pressure via a further valve control device arranged in its charging position, and moving a valve piston of the further valve control device to its suspension position, in which the valve piston at least partially forms a fluid path between the accumulator and the consumer in a gradually increasing manner, and at the same time the suspension pressure in the consumer and the actual charge pressure of the accumulator are equalized to one another via the fluid path and accordingly match each other more and more. Actively filling the accumulator to the initial charge pressure ensures that the accumulator is always filled and thus always ready to perform its suspension function.

[0026] In another preferred embodiment, the initial charge pressure corresponds to the maximum working pressure of the actuator and the adaptation of the initial charge pressure is performed by discharging the accumulator, which ensures that the suspension actuation at most results in a controlled and gradual advance of the piston rod of the consumer, which has no more significant safety consequences than an advancement motion. Furthermore, the accumulator is filled to the maximum working pressure only once before the suspension actuation, which increases the energy efficiency and lifespan of the accumulator and improves the response behavior of the machine, in particular as opposed to a continuous adaptation of the charge pressure.

[0027] In a particularly preferred embodiment, the suspension pressure and the charge pressure are detected by a pressure sensor in each case, and after filling the accumulator and before connecting it to the consumer, the initial charge pressure is adapted to the suspension pressure by discharging or charging the accumulator depending on the detected pressure, so that the suspension pressure is equal to the actual charge pressure, thereby minimizing or even preventing movement of the consumer piston rod during suspension operation.

[0028] In another preferred embodiment, the damping ratio can be adjusted such that the valve piston of the separate valve control device is positioned at an intermediate position between the suspension position and an adjacent separation position.

[0029] In the following, the actuation device according to the invention will be explained in more detail with reference to the drawings, which are principle views and are not drawn to scale. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 shows a first embodiment of an actuation device according to the invention in the form of a hydraulic circuit diagram. [Diagram 2] FIG. 2 shows in the form of a hydraulic circuit diagram a second embodiment of an actuation device according to the invention. [Diagram 3] FIG. 3 shows in the form of a hydraulic circuit diagram a third embodiment of an actuation device according to the invention. [Figure 4]FIG. 4 shows in the form of a hydraulic circuit diagram a fourth embodiment of an actuation device according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The figures show an actuation device according to the invention for a fluid-operable consumer device 10 in the form of an actuator 10. The actuation device comprises a valve control device V1 for controlling the alternating action of the actuator 10 and a suspension device 14 connected between this valve control device V1 and the actuator 10. The suspension device 14 comprises an accumulator 16 and a further valve control device V2, the valve piston 20 of which can be infinitely displaced in a valve housing. The valve piston 20 of the further valve control device V2 can be arranged in a suspension position V2.V, in which position the valve piston 20 connects the accumulator 16 with the actuator 10 via a fluid path through the further valve control device V2.

[0032] The actuator is used for fluid pressure matching between the charged pressure ps of the accumulator 16 and a suspension pressure pa that holds the load in the actuator 10, for the purpose of suspending the piston rod unit 22 of the actuator 10, in a particularly damped manner, by the charged pressure ps of the accumulator 16.

[0033] The actuation device has a pressure supply 24, the suction side of which is connected to a fluid storage tank 26 and the high pressure side of which is connected via a fluid line to a piston side working chamber 28 of the actuator 10. A rod side working chamber 30 of the actuator 10 is connected to the tank 26 via another fluid line. A valve control device V1 is connected as a main control valve to both fluid lines forming a kind of main fluid branch. Depending on the switching position of the valve V1, the high pressure side can also be the rod side. A suspension device 14 is connected in parallel to the valve control device V1 to both these fluid lines in a kind of secondary fluid branch and can be selectively connected.

[0034] A first connection V2.1 of the further valve control device V2 of the suspension device 14 is connected via a fluid line to a branch point in the fluid line between the valve control device V1 and the piston-side working chamber 28 of the actuator 10. A second connection V2.2 of the further valve control device V2 is connected via another fluid line to a branch point in the fluid line between the valve control device V1 and the pressure supply connection P of the actuator, to which the pressure supply source 24 is connected on the high-pressure side. A third connection V2.3 of the further valve control device V2 is connected to the fluid side of the accumulator 16.

[0035] The further valve control device V2 is designed as a proportional valve. The end position V2.V of the valve piston 20 of the further valve control device V2 corresponds to a suspension position V2.V, in which the valve piston 20 connects the first connection V2.1 and the third connection V2.3 of the further valve control device V2 to one another, separates the second connection V2.2 from all other connections of the further valve control device V2 and connects the rod side (V2.4) with the tank (V2.5). To operate the valve piston 20, a force can be applied to one of its control sides 32 by an operating device V5, 32 against the force of a compression spring 34 towards one of the end positions V2.V in the form of a suspension position V2.V.

[0036] The further valve control device V2 is arranged to incrementally, i.e. gradually, form a fluid path between the piston-side working chamber 28 of the actuator 10 and the accumulator 16 when its valve piston 20 moves to the suspension position V2.V, so that the suspension pressure pa, which holds the load in the piston-side working chamber 28 of the actuator 10, and the filling pressure ps of the accumulator 16 are equalized to each other via the fluid path and accordingly match each other more and more. Such a pressure matching is considered a passive pressure matching. During the incremental formation of this fluid path and when the valve piston 20 is located in the suspension position V2.V, the rod-side working chamber 30 of the actuator 10 is discharged towards the tank 26. A gradual depressurization of the rod-side chamber 30 is also performed in the same way.

[0037] The valve piston 20 of the further valve control device V2 can furthermore be arranged in a filling position V2.III, in which position the valve piston 20 separates the first connection V2.1 of the further valve control device V2 from all other connections and connects its second connection V2.2 and its third connection V2.3 to one another via a fluid path, to which a throttle 72 or an orifice can be connected. Between its suspension position V2.V and the filling position V2.III, the valve piston 20 of the further valve control device V2 can be arranged in a separation position V2.IV, in which position the valve piston 20 separates all connections of the further valve control device V2 from one another.

[0038] An operable load-holding valve V3 is connected in the fluid path between the valve control device V1 and the piston-side working chamber 28 of the actuator 10. Here, the load-holding valve is a general term for a line break safety valve and a down brake valve.

[0039] The actuation device further comprises a control unit 36 ​​to which at least one input device 38 and at least one sensor device 40 for detecting state values ​​are connected. An operator of the actuation device can selectively activate or deactivate the suspension via the input device 38, 42 as well as enter control commands for the actuator 10 via this input device 38 or a further input device 44 and enter the damping rate of the suspension via this input device 38 or a further input device 46. As sensor device 40, a displacement sensor 48 is provided in particular for detecting speed values.

[0040] A non-return valve V4 is connected in the fluid line between a branch point in the fluid line between the pressure supply connection P and the valve control device V1 and a second connection V2.2 of the further valve control device V2 and opens towards the further valve control device V2 against the force of a compression spring. The non-return valve V4 prevents the accumulator 16 from emptying when the valve piston 20 of the further valve control device V2 is located in the filling position V2.III and the pressure of the pressure supply 24 is lower than the charge pressure ps.

[0041] A first connection V1.1 of the valve control device V1 is connected via a fluid line to the pressure supply connection P, a second connection V1.2 is connected in fluid communication with the tank connection T via another fluid line. A third connection V1.3 of the valve control device V1 is connected via another fluid line to the piston-side working chamber 28 of the actuator 10, and a fourth connection V1.4 is connected via another fluid line to the rod-side working chamber 30 of the actuator 10. The valve piston 50 of the valve control device V1, designed as a 4 / 3 proportional directional control valve V1, can be moved starting from its inoperative first position V1.I, respectively, shown in the figure, against the force of a compression spring 54 into its second position V1.II and further against the force of a compression spring 52 into its third position V1.III. The second position V1.II and the third position V1.III correspond to the two end positions V1.II, V1.III of the valve piston 50. In the first position V1.1, the inactivated valve piston 50 is held by both compression springs 52, 54 and separates all connections of the valve control device V1 from each other. When placed in the second position V1.II, the valve piston 50 of the valve control device V1 connects its first connection V1.1 with its fourth connection V1.4 to each other as well as its third connection V1.3 with its second connection V1.2 to each other. When placed in the third position V1.III, the valve piston 50 of the valve control device V1 connects its first connection V1.1 with its third connection V1.3 to each other as well as its fourth connection V1.4 with its second connection V1.2 to each other.

[0042] In the first to third exemplary embodiments shown in Figures 1 to 3, a control fluid pressure pr can be applied to one control side 32 of the valve piston 20 of the further valve control device V2 against the force of the compression spring 34 towards one end position V2.V in the form of a suspension position V2.V. To control the control fluid pressure pr, a proportional pressure control valve V5 is provided, whose valve piston is electromagnetically actuable against the force of the control fluid pressure pr. For this purpose, the control unit 36 ​​operates an electromagnetic actuator 56 of the proportional pressure control valve V5.

[0043] The control fluid pressure pr is tapped at a first connection V5.1 of the proportional pressure control valve and fed via a control line to the control side of the valve piston of the proportional pressure control valve V5. The second connection V5.2 of the proportional pressure control valve V5 is connected with the pilot fluid pressure connection C of the actuator, and the third connection V5.3 is connected with the tank line 58. Optionally, the proportional pressure control valve can be fed from a pressure supply connection P.

[0044] Furthermore, the control fluid pressure pr is sent via another control line and a control connection 60 to one control side 32 of the valve piston 20 of the further valve control device V2. To operate the load holding valve V3, the control fluid pressure pr is tapped at a branch point of the control line between the proportional pressure control valve V5 and the further valve control device V2 and sent to the load holding valve V3 via another control line.

[0045] In the first embodiment according to FIG. 1, the further valve control device V2 is designed as a 5 / 3-way valve. The fluid path from the rod-side working chamber 30 of the actuator 10 to the tank 26 passes through the further valve control device V2. For this purpose, the fourth connection V2.4 of the further valve control device V2 is connected via a fluid line to the branch point of the fluid line between the rod-side working chamber 30 of the actuator 10 and the valve control device V1. The fifth connection V2.5 of the further valve control device V2 is connected via a fluid line to the tank line 58. In the suspension position V2.V, the fourth connection V2.4 is connected with the fifth connection V2.5, which is separated from all other connections of the further valve control device V2 in the filling position V2.III and in the disconnected position V2.IV, respectively. A control pressure is tapped in the tank line 58 and is sent via the control line and the further control connection 62 to the further control side 64 of the valve piston 20 of the further valve control device V2.

[0046] In the second embodiment according to FIG. 2, the further valve control device V2 is designed as a 3 / 3-way valve. The fluid path from the rod-side working chamber 30 of the actuator 10 to the tank 26 passes through a drain valve V6 designed as a 2 / 2 proportional directional control valve V6. In the first, non-operated end position V6.I shown in FIG. 2, the valve piston 66 of the drain valve V6 separates its two connections V6.1, V6.2 from each other, whereas in the second end position V6.II these connections V6.1, V6.2 are connected to each other. To operate the drain valve V6, a control fluid pressure pr acts on the control side 68 of its valve piston 66, which is tapped at the branch point of the control line between the proportional pressure limiting valve V5 and the further valve control device V2. This control fluid pressure pr makes it possible to move the valve piston 66 of the drain valve V6 from its first end position V6.I to its second end position V6.II against the force of a compression spring 70.

[0047] In the first and second embodiment, the filling position V2.III of the valve piston 20 of the further valve control device V2 corresponds to the other end position V2.III, which is not actuated. Furthermore, in both these embodiments, the accumulator 16 can be connected to a tank 26 via a shut-off valve, in particular a throttle or an orifice, in order to release the charged pressure ps or the charged fluid.

[0048] In the third exemplary embodiment according to FIG. 3, the further valve control device V2 is designed as a 6 / 5-way valve. The fluid path from the rod-side working chamber 30 of the actuator 10 to the tank 26 passes through the further valve control device V2. This further valve control device V2 has a fourth connection V2.4 and a fifth connection V2.5 as well as a further control connection 62, which are connected to the components of the actuator according to the first exemplary embodiment according to FIG. 1 and are connected to each other or separated from each other in the suspension position V2.V and the separation position V2.IV of the valve piston 20. Furthermore, the further valve control device V2 has a sixth connection V2.6, which is connected to a pressure source 24 in the form of an adjustable pump 24 via a load-sensing connection LS and a corresponding line for the purpose of regulating the pressure. The LS signal can also be transmitted to the pump electronically via a pressure transmitter (at connection LS). In this way, a pump hose line would not be necessary. The pump 24 is also connected on the high-pressure side to the pressure supply connection P of the actuator. When the valve piston 20 of the further valve control device V2 is located in its filling position V2.III, its second connection V2.2 and its third connection V2.3 are connected to the sixth connection V2.6 via a fluid path provided with a branch point. A throttle 72 or an orifice can be connected to the fluid path between the second connection V2.2 of the further valve control device V2 and this branch point.

[0049] In a third embodiment, the valve piston 20 of the further valve control device V2 can furthermore be arranged in a discharge position V2.I, in which its third connection V2.3 and its fifth connection V2.5 are connected to one another via a fluid path, and the remaining connections are isolated from one another. A throttle 76 or an orifice can be connected to this fluid path. The valve piston 20 of the further valve control device V2 can be arranged in this isolation position V2.II between its discharge position V2.I and its filling position V2.III, in which the valve piston 20 isolates all the connections of the further valve control device V2 from one another. Furthermore, for detecting the respective fluid pressures pa, ps in the fluid line between the piston-side working chamber 28 of the actuator 10 and the further valve control device V2, as well as in the fluid line between the further valve control device V2 and the accumulator 16, a pressure sensor 40, 78, 80 is provided in each case and is connected to the control unit 36 ​​for transmitting the measured values.

[0050] By using the pressure sensor 80 to monitor the charge pressure ps, it is possible to dispense with an additional pressure limiting valve to ensure a maximum charge pressure in the accumulator, especially after a safety assessment.

[0051] In the first to third embodiments, in particular when the suspension system is in operation, the proportional control groove of the respective valve piston 20 of the further valve control device V2 and / or the proportional pressure control valve V5 ensures a gentle movement of the piston rod 22 of the actuator 10. Instead of operating the valve piston 20 of the further valve control device V2 by means of the proportional pressure control valve V5, this operation can also be performed by an electromagnetic actuator 82 according to the fourth embodiment.

[0052] In the fourth exemplary embodiment according to Fig. 4, the further valve control device V2 is designed and connected in accordance with the further valve control device V2 of the third exemplary embodiment. Correspondingly connected pressure sensors 40, 78, 80 are also provided in accordance with the third exemplary embodiment. In contrast to the third exemplary embodiment, an electromagnetic actuator 82 is provided in the fourth exemplary embodiment for operating the valve piston 20 of the further valve control device V2, the electric motor 84 of which can be operated by the control unit 36 ​​via an electric line. Furthermore, the load holding valve V3 is directly controlled by the control unit 36.

[0053] In the third and fourth embodiments, the discharge position V2.I of the valve piston 20 of the further valve control device V2 corresponds to its other non-actuated end position V2.I. The filling position V2.III is provided between the discharge position V2.I and the suspension position V2.V.

[0054] The actuating device 10 is designed as an actuating cylinder 10. The actuating device is part of a mobile work machine (not shown), in particular a construction machine such as a wheel loader or a mobile excavator, and is provided with a lifting mechanism having the actuating cylinder 10. A lifting mechanism suspension system comprising the actuating device and the lifting mechanism serves to increase the comfort and driving safety of the work machine.

[0055] The control unit 36 ​​for operating the further valve control device V2 can correspond to the control unit 36 ​​of the working machine. Alternatively, the control unit 36 ​​for controlling the further valve control device V2 can form a unit with the further valve control device V2, which unit is separated in hardware technology and spatially from the control unit of the working machine. The latter variant has the advantage that fewer control signals are required for communication between the control unit 36 ​​of the further valve control device V2 and the control unit of the working machine. By doing so, the control unit of the working machine can be designed more simply, since it is not necessary to provide inputs and outputs for the suspension functions.

[0056] The valve control device V1 can be provided in a main control block and the suspension device 14, in particular the additional valve control device V2, can be provided as a mounting disk for the main control block. Alternatively, the valve control device V1 and the suspension device 14 can be of monoblock construction.

[0057] The valve control device V1 and the further valve control device V2 can be operated independently of one another, in particular by the control unit 36, and correspondingly the respective valve pistons 20, 50 can also be moved independently of one another.

[0058] The actuators according to the first and second embodiments operate as follows.

[0059] Filling process step: The accumulator 16 is filled to an initial charge pressure via a further valve control device V2 arranged at a filling position V2.III. The initial charge pressure can correspond to the maximum operating pressure of the actuator, which corresponds to the maximum operating pressure of the lift mechanism. The further valve control device V2 is connected to a pressure supply connection P for supplying the actuator 10, so that the accumulator filling can take place passively every time the pump pressure operating the actuator 10 increases. However, the accumulator 16 is preferably filled actively, independently of the operation of the actuator 10.

[0060] This is followed by a separation process step: after filling the accumulator 16, the valve piston 20 of the further valve control device V2 can be moved to a separation position V2.IV, which is provided between the filling position V2.III and the suspension position V2.V.

[0061] This is followed by a check process step: in order for the control unit 36 ​​to activate the suspension, for example, at least one of the following conditions must be fulfilled: the suspension is activated, in particular permanently, via the corresponding input device 38, 42; the suspension is not permanently deactivated via the input device 38, 42; the work machine exceeds a certain driving speed, which is detected by the speed sensor 40, 48. The control unit 36 ​​can check the plausibility of the activation of the suspension on the basis of a control command for the actuator 10, which is supplied by the corresponding input device 38, 44. In this case, it can be ensured that the suspension is only activated if the actuator 10 is not operated by the operator via the input device 38, 44.

[0062] This is followed by the process steps of passive pressure adaptation: if the preconditions that can be set are met, the load-holding valve V3 is opened if it is in the closed position in order to activate the suspension. Furthermore, the valve piston 20 of the further valve control device V2 is moved, in particular starting from its isolation position V2.IV to its suspension position V2.V. In so doing, the valve piston 20 gradually increases the fluid path between the accumulator 16 and the piston-side working chamber 28 of the actuator 10, so that the suspension pressure pa in this working chamber 28 and the actual charge pressure ps of the accumulator 16 are equalized via the fluid path and accordingly gradually match each other more and more. At the same time, the rod-side working chamber 30 of the actuator 10 is connected to the tank 26.

[0063] The actuators according to the third and fourth embodiments operate as follows.

[0064] When the actuator is deactivated, for example when the working machine is switched off, the valve piston 20 of the further valve control device V2 is located in its non-operated discharge position V2.I, whereby the accumulator 16 is discharged towards the tank 26.

[0065] When the actuator is subsequently actuated, for example when the working machine is switched on, the valve piston 20 first starts from the discharge position V2.I and moves to a further separation position V2.II which is provided between the discharge position V2.I and the filling position V2.III.

[0066] This is followed by a filling process step according to the first and second embodiment, where the charging pressure ps can be monitored by the assigned pressure sensor 80 and / or fed to the pump 24 via a load sensing line. The filling of the accumulator 16 can be coordinated with the actual operating degree 18 of the working machine drive unit, so that the filling of the accumulator 16 only takes place if the working machine drive unit is not actually operating at full capacity or has sufficient reserve power. For this purpose, the operating degree 18 of the drive unit is detected and sent to the control unit 36. The drive unit can be designed as a combustion engine or an electric motor. Depending on the charging pressure 16 and the operating degree 18 of the drive unit, the filling speed of the accumulator 16 can be preset and in particular adjusted proportionally.

[0067] The valve piston 20 can then return again to the separation position V2.II located between the discharge position V2.I and the filling position V2.III.

[0068] When the suspension is actuated, first the check process steps are carried out according to the first and second embodiment, followed by an active pressure adaptation in the piston-side working chamber 28 of the actuator 10 to the suspension pressure pa, which holds the load of the pre-charge pressure ps. For this purpose, based on the measured values ​​of the two pressure sensors 40, 78, 80, the differential pressure between the pre-charge pressure ps and the suspension pressure pa is determined by the control unit 36, on the basis of which the pre-charge pressure ps of the accumulator 16 is actively adapted to the suspension pressure pa. Thus, if the pre-charge pressure ps is higher than the suspension pressure pa when the suspension is actuated, the valve piston 20 is moved to its discharge position V2.I and the accumulator 16 is discharged towards the tank 26 until the pre-charge pressure ps is equal to the suspension pressure pa. Conversely, if the suspension pressure pa is higher than the pre-charge pressure ps when the suspension is actuated, the valve piston 20 is moved to the filling position V2.III and the accumulator 16 is filled until the pre-charge pressure ps is equal to the suspension pressure pa. This is considered as an active pressure adaptation. If active pressure adaptation is carried out after the working machine has reached a certain driving speed, the suspension has been activated and the working machine has been accelerated to practically full operation of the drive unit, it is advantageous if the accumulator 16 is initially filled to the maximum operating pressure, since in that case it is only necessary to release the fluid pressure ps from the accumulator 16 towards the tank 26 for active pressure adaptation, without requiring the power of the drive unit.

[0069] This is followed by passive pressure matching process steps according to the first and second embodiments, and optionally separation process steps.

[0070] In each embodiment, the valve piston 20 takes on various intermediate positions along its path of movement, in particular starting from the separation position V2.IV between the suspension position V2.V and the filling position V2.III towards the suspension position V2.V, which correspond to different damping rates of the suspension. In this case, the damping of the suspension is maximum when the fluid connection between the accumulator 16 and the actuator 10 is first established and then decreases as the valve piston 20 moves towards its suspension position V2.V. When the valve piston 20 finally reaches its suspension position V2.V, free suspension is possible, so that the fluid path between the accumulator 16 and the actuator 10 is substantially free of flow cross-section reduction mechanisms. The damping rate of the suspension can therefore be preset by placing the valve piston 20 in an intermediate position between the separation position V2.IV and the suspension position V2.V as described above, via the corresponding input device 38, 46.

[0071] In the first to third embodiments, the operation of the valve piston 20 of the further valve control device V2 is carried out via a proportional pressure limiting valve V5 starting from the control unit 36, and in the fourth embodiment, via an electromagnetic actuator 82 starting from the control unit 36.

Claims

1. 1. An actuation device for at least one fluid-operable consumer (10), such as a hydraulic actuator, comprising at least one valve control device (V1) for controlling the alternating operation of each consumer (10), and at least one suspension device (14) connected between the valve control device (V1) and each consumer (10), the suspension device (14) having a further valve control device (V2), the valve piston (20) of which is infinitely movable in a corresponding valve housing, characterized in that in a suspension position (V2.V) of the valve piston (20) of the further valve control device (V2), an accumulator (16) of the suspension device (14) is connected to the respective consumer (10) via a fluid path passing through the further valve control device (V2).

2. 2. The actuation device according to claim 1, wherein the further valve control device (V2) is set so that, when operated accordingly, the suspension pressure (pa) in the consumer and the charge pressure (ps) of the accumulator (16) are gradually equalized via the valve control device (V2) and are accordingly adapted to each other.

3. 3. The actuation device according to claim 2, characterized in that the further valve control device (V2) forms a fluid path at least partially gradually increasing when its valve piston (20) moves to the suspension position (V2.V), and at the same time the suspension pressure (pa) in the consumer (10) and the charge pressure (ps) in the accumulator (16) are equalized to one another via the fluid path and accordingly are set to gradually match one another more and more.

4. 2. The actuation device according to claim 1, characterized in that the valve piston (20) separates the pressure supply connection (P) of the actuation device and the accumulator (16) from each other while the fluid path is formed incrementally and / or when the valve piston (20) is located in the suspension position (V2.V).

5. 3. The actuation device according to claim 2, characterized in that a proportional pressure control valve (V5) is provided for operating the further valve control device (V2), and a control fluid pressure (pr) can be applied to the control side (32) of the valve piston (20) of the further valve control device (V2) via the proportional pressure control valve (V5).

6. 6. An actuation device according to claim 5, characterized in that the proportional pressure control valve (V5) is electromagnetically actuatable against the force of the control fluid pressure (pr).

7. 5. The actuation device according to claim 4, characterized in that the valve piston (20) of the further valve control device (V2) can be arranged in a filling position (V2.III) in which the accumulator (16) is connected to the pressure supply connection (P) via a further fluid path through the further valve control device (V2) for filling it, and preferably the consumers (10) are connected to the pressure supply connection (P) via a respective one valve control device (V1).

8. 8. The actuation device according to claim 7, characterized in that the valve piston (20) of the further valve control device (V2) can be arranged in at least one separation position (V2.II, V2.IV) separating all connections of the further valve control device (V2) from one another, and that a separation position (V2.IV) is provided between the suspension position (V2.V) and the charging position (V2.III) and / or a further separation position (V2.II) is provided between the charging position (V2.III) and a discharge position (V2.I) of the valve piston (20) of the further valve control device (V2), and in the further separation position (V2.II) the accumulator (16) is connected to a tank connection (T) via the further valve control device (V2).

9. A proportional pressure control valve (V5) is provided to operate the other valve control device (V2), and a control fluid pressure (pr) can be applied to the control side (32) of the valve piston (20) of the other valve control device (V2) via the proportional pressure control valve (V5), the valve piston (20) of the further valve control device (V2) can be placed in a charging position (V2.III) in which the accumulator (16) is connected to the pressure supply connection (P) via a further fluid path through the further valve control device (V2) for charging thereof, the valve piston (20) of the further valve control device (V2) can be arranged in at least one separation position (V2.II, V2.IV) separating all connections of the further valve control device (V2) from one another, wherein a separation position (V2.IV) is provided between the suspension position (V2.V) and the charging position (V2.III) and / or a further separation position (V2.II) is provided between the charging position (V2.III) and a discharge position (V2.I) of the valve piston (20) of the further valve control device (V2), and in the further separation position (V2.II) the accumulator (16) is connected to a tank connection (T) via the further valve control device (V2), 5. An actuation device according to claim 4, characterized in that a drain valve (V6) is provided in the fluid connection between the consumer (10) and the tank connection (T), and the control fluid pressure (pr) acts on a control side (68) of the valve piston (66) to operate the drain valve (V6).

10. 3. The actuation device according to claim 2, characterized in that a pressure sensor (40, 78) for detecting the suspension pressure (pa) of the consumer (10) and / or a further pressure sensor (40, 80) for detecting the charge pressure (ps) of the accumulator (16) are provided, the further pressure sensors (40, 80) being connected to a control unit (36) of the actuation device for transmitting their respective pressure measurements.

11. There is provided a pressure sensor (40, 78) for detecting the suspension pressure (pa) of the consumer (10) and / or another pressure sensor (40, 80) for detecting the filled pressure (ps) of the accumulator (16), said another pressure sensor (40, 80) being connected to a control unit (36) of the actuating device for transmitting its respective pressure measurements; 6. An actuation device according to claim 5, characterized in that a load holding valve (V3) is provided, which ensures the suspension pressure (pa) in the consumer (10) and can be operated by the proportional pressure control valve (V5) using the control fluid pressure (pr) or via an additional connection of the actuation device or by the control unit (36).

12. A method for operating at least one fluid-operable consumer (10) by means of an actuation device according to any one of claims 1 to 11, comprising the steps of: - a method step of filling the accumulator (16) to an initial charging pressure via the further valve control device (V2) arranged in its charging position (V2.III); a method step of moving the valve piston (20) of the further valve control device (V2) to its suspension position (V2.V), wherein the valve piston (20) at least partially forms a fluid path between the accumulator (16) and the consumer (10) in an increasingly progressive manner, and at the same time the suspension pressure (pa) in the consumer (10) and the actual charged pressure (ps) of the accumulator (16) are equalized to each other via the fluid path and accordingly become increasingly compatible with each other.

13. 13. The method according to claim 12, characterized in that the suspension pressure (pa) and the charge pressure (ps) are detected by at least one pressure sensor (40, 78, 80), respectively, and that after filling the accumulator (16) to the initial charge pressure and before connecting it to the consumer (10), the initial charge pressure is made equal to the suspension pressure (pa) by discharging or charging the accumulator (16) depending on the detected pressure (pa, ps).

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