Fluid power valve device and method for operating a fluid power valve device

Abstract

Fluid power valve assembly (1) comprising a first rotary valve (2), a second rotary valve (3) and an actuator (10), wherein each of the rotary valves (2, 3) has a rotary valve (6, 7) arranged in a rotary valve housing and driven by the actuator (10) via a drive shaft (11), wherein the first rotary valve (2) is rigidly coupled to the drive shaft (11), wherein the second rotary valve (3) is coupled to the drive shaft (11) via a freewheel (12), wherein the freewheel (12) establishes a rigid connection between the drive shaft (11) and the second rotary valve (3) in a first direction of rotation of the drive shaft (11) and decouples the second rotary valve (3) from the drive shaft (11) in a second direction of rotation opposite to the first direction of rotation, characterized in that the freewheel (12) is directly connected to the drive shaft (11). is coupled.

Description

[0001] The invention relates to a fluid power valve assembly comprising a first rotary valve, a second rotary valve, and an actuator, wherein each of the rotary valves has a rotary valve arranged in a rotary valve housing and driven by the actuator via a drive shaft, wherein the first rotary valve is rigidly coupled to the drive shaft, and wherein the second rotary valve is coupled to the drive shaft via a freewheel, wherein the freewheel establishes a rigid connection between the drive shaft and the second rotary valve in a first direction of rotation of the drive shaft and decouples the second rotary valve from the drive shaft in a second direction of rotation opposite to the first. The invention further relates to a method for operating such a fluid power valve assembly.

[0002] For example, German patent application DE 10 2013 010 536 B3 is known from the prior art. This document describes a valve having two valve elements arranged in a valve housing, which can be actuated by an actuating rod driven by an electrodynamic actuator. The electrodynamic actuator includes a coil assembly that is coaxially and axially fixed to the actuating rod, so that the actuating rod moves linearly in its longitudinal direction to actuate the valve elements.

[0003] Document WO 2017 / 217 112 A1 discloses a switchable fluid control valve with a valve chamber, opening / closing orifices, and open orifices that open into the valve chamber and through which a fluid flow is formed in a valve body. A primary valve opens and closes the opening / closing orifices by rotating about a single central axis. A secondary valve, positioned between the primary valve and the opening / closing orifices, is arranged opposite the opening / closing orifices and rotates about the single central axis.

[0004] The prior art also includes the publication DE 10 2016 102 583 A1.

[0005] The object of the invention is to propose a fluid power valve device which has advantages over known valve devices, in particular enabling the independent adjustment of several valves in a simple and flexible manner.

[0006] According to the invention, this is achieved with a fluid power valve device having the features of claim 1. It is provided that the freewheel is directly coupled to the drive shaft.

[0007] The fluid power valve assembly serves to adjust the cross-sectional area of ​​the flow between at least one fluid inlet and at least one fluid outlet. For example, the valve assembly has at least as many fluid outlets as fluid inlets, with each fluid inlet being assigned at least one or more fluid outlets. It can therefore be provided that the valve assembly can be used to adjust the cross-sectional area of ​​the flow between exactly one fluid inlet and exactly one fluid outlet, or the respective cross-sectional area of ​​the flow between each fluid inlet and its corresponding at least one fluid outlet.

[0008] Particularly preferably, the valve assembly has a fluid inlet and several fluid outlets associated with this fluid inlet, wherein, depending on a setting of the valve assembly, the fluid supplied at the fluid inlet is directed to none of the fluid outlets, exclusively to one of the fluid outlets, or to several of the fluid outlets. This means that, depending on the setting of the valve assembly, a specific flow cross-sectional area is established between the fluid inlet and each of the fluid outlets, which can be non-zero but can also be zero to block the respective fluid connection between the fluid inlet and the corresponding fluid outlet.

[0009] The valve assembly has several rotary valves for adjusting the flow cross-sectional area between the respective fluid inlet and outlet, namely the first rotary valve and the second rotary valve. Each of these rotary valves in turn has a rotary slide located in its respective rotary valve housing. The rotary valve housings of the individual rotary slides can, of course, also be configured as a single, common rotary valve housing. The rotary slide is rotatably mounted within the rotary valve housing about a pivot axis.

[0010] Each rotary valve has at least one inlet and at least one outlet. Depending on the rotational angle of the rotary valve within the valve body, a specific flow cross-sectional area exists between the inlet and the outlet. It can be provided, for example, that the inlets of the rotary valves are fluidically independent of each other and connected to separate fluid inlets of the valve assembly, and that, analogously, the outlets of the rotary valves are fluidically independent and connected to fluid outlets of the valve assembly.

[0011] However, it can also be provided that the inlets of the rotary slide valves are each fluidically connected to the single fluid inlet of the valve assembly, so that the rotary slide valves are each connected to the fluid inlet of the valve assembly on the inlet side. The outlets of the rotary slide valves are preferably each fluidically independently connected to fluid outlets of the valve assembly, in particular each outlet to exactly one of the fluid outlets. Of course, it is also possible here that the outlets of several or all rotary slide valves are fluidically connected to one of the fluid outlets or to the single fluid outlet of the valve assembly.

[0012] For example, in a first rotary position of the rotary valve, a fluid connection with a first flow cross-sectional area exists between the respective inlet and outlet, whereas in a second rotary position, the fluid connection has a second flow cross-sectional area that differs from the first. For example, in the first rotary position of the rotary valve, a fluid connection with a first flow cross-sectional area exists between the fluid inlet and one of the first fluid outlets, while a second fluid outlet is fluidically decoupled from the fluid inlet. In the second rotary position, however, the first fluid outlet is fluidically decoupled from the fluid inlet, while the second fluid outlet, with a specific second flow cross-sectional area, is in flow connection with the fluid inlet.The first flow cross-sectional area and the second flow cross-sectional area can have the same value or be different from each other.

[0013] It is therefore possible that the multiple rotary valves are fluidically connected to the same fluid inlet of the valve assembly, so that the fluid supplied at the fluid inlet can be distributed to multiple fluid outlets by means of the rotary valves. However, it is also possible that each of the rotary valves has a separate fluid inlet, so that the above descriptions can be applied to each of the rotary valves or each of the rotary valves.

[0014] The adjustment of the valve assembly, i.e., the actuation or rotation of the rotary valves within the rotary valve housing, is carried out by means of the actuator motor. The drive shaft is connected to the actuator motor, specifically to a motor shaft of the actuator motor, via which the actuator motor can drive the respective rotary valve. The actuator motor is preferably an electric motor. However, other types of motors can also be used.

[0015] The rotary valves' rotary spools can be actuated, and in particular selectively actuated, by means of the actuator motor. For this purpose, the drive shaft is rigidly coupled to the first rotary valve, or rather, to the rotary spool of the first rotary valve. The second rotary valve, or rather, the rotary spool of the second rotary valve, is coupled to the drive shaft via the freewheel, i.e., only indirectly. This means that a rotary movement of the drive shaft is always transmitted to the first rotary valve, regardless of the drive shaft's direction of rotation. The coupling between the second rotary valve and the drive shaft, however, depends on the drive shaft's direction of rotation. In one direction of rotation, the freewheel establishes a rigid connection between the drive shaft and the second rotary valve.In the case of a second direction of rotation opposite to the first direction, the freewheel decouples the second rotary valve from the drive shaft.

[0016] In the first direction of rotation, the second rotary valve is fixedly coupled to the drive shaft, allowing the actuator motor to move the rotary spool of the second rotary valve. In the second direction of rotation, when the second rotary valve is decoupled from the drive shaft, it remains in its current angular position even when the actuator motor and thus the drive shaft rotate. In other words, the rotary spool of the second rotary valve is fixed within the rotary valve housing as long as it is decoupled from the drive shaft. This is achieved, for example, by sufficient friction between the rotary spool and the rotary valve housing.

[0017] If this description refers to only one rotary valve and / or one rotary valve, the corresponding specifications apply to all rotary valves and / or rotary valves of the fluid power system, especially unless otherwise indicated. Numerous advantages can be achieved with the described design of the fluid power valve system. For example, the rotary valves can be adjusted independently of each other, namely by moving the rotary valve of the first rotary valve independently of the rotary valve of the second rotary valve.

[0018] Furthermore, the only actuator used for the flexible repositioning or rotation of the rotary valves is the common actuator motor, which is the sole actuator motor in the fluid power system. No additional actuator motor is provided to drive the rotary valves. The selective actuation of the rotary valve is achieved in a structurally simple manner, namely through the use of the freewheel.

[0019] The mounting of the rotary valves within the rotary valve housing can be configured in virtually any way. For example, the rotary valves can be radially mounted on the drive shaft and axially supported by at least one sealing assembly, which acts as a seal against the rotary valves. A combination of radial and axial mounting using these sealing assemblies is also possible. The sealing assemblies are preferably spring-loaded in the direction of the respective rotary valve, thus compensating for tolerances.

[0020] The invention provides that the freewheel is directly coupled to the drive shaft. On the input side, the freewheel is directly connected to, or coupled to, the drive shaft. On the output side, it is coupled to the second rotary valve, whereby this coupling can be direct or indirect. Preferably, however, the freewheel engages directly with the second rotary valve or its rotary valve on the output side. If the freewheel is directly coupled to the drive shaft, it is driven directly by the drive shaft, or at least not via the first rotary valve or its rotary valve.

[0021] In the case of an indirect coupling not according to the invention, the freewheel is connected to the drive shaft via the first rotary valve or its rotary valve. This means that a rotary movement of the drive shaft is transmitted to the second rotary valve only via the first rotary valve or its rotary valve. The described design of the fluid-technical valve assembly is technically simple and cost-effective to implement.

[0022] In a further preferred embodiment of the invention, the first rotary valve has a first coupling device and the second rotary valve has a second coupling device, wherein the first coupling device and the second coupling device are each coupled to the freewheel. The connection of the freewheel to the drive shaft is thus achieved only indirectly via the two coupling devices, i.e., the first coupling device and the second coupling device. For this purpose, the freewheel engages the first rotary valve on the input side via the first coupling device. On the output side, the freewheel is coupled to the second rotary valve via the second coupling device. The coupling devices can each be configured in any way. They particularly preferably each have a toothed connection or are in the form of a toothed connection.The use of the coupling devices enables a particularly simple construction of the valve assembly and a reliable connection of the rotary valves to the drive shaft.

[0023] A further development of the invention provides that the first coupling device is coupled to an input of the freewheel which is coupled to the drive shaft, and the second coupling device is coupled to an output of the freewheel. In other words, the freewheel is connected to the drive shaft via the first coupling device on the input side and to the second rotary valve via the second coupling device on the output side. This means that the second rotary valve, or rather its rotary valve, is connected to the drive shaft exclusively via the second coupling device, the freewheel, the first coupling device, and the first rotary valve.

[0024] This results in a particularly high degree of flexibility for the fluid power valve assembly, especially with regard to the arrangement of the two rotary valves relative to each other. For example, the two rotary valves can be arranged coaxially, so that the axes of rotation of their rotary slides coincide. Alternatively, the rotary valves can be arranged such that the axes of rotation of their rotary slides are spaced apart, parallel to each other, or skew to each other.

[0025] A preferred further embodiment of the invention provides that the first coupling device is coupled to an input of the freewheel via the drive shaft or to the drive shaft via an input coupling device of the freewheel input. In the former case, the freewheel input is preferably connected directly to the drive shaft. In this case, the first coupling device serves, for example, to establish a direct connection between the drive shaft and the first rotary valve. The freewheel is thus only indirectly coupled to the first rotary valve, namely via the drive shaft.

[0026] In the case of coupling the first coupling device to the drive shaft via the input coupling device, the first rotary valve is only indirectly connected to the drive shaft, namely via the inlet of the freewheel. This means that the freewheel is connected on the input side to both the drive shaft and the first rotary valve, so that a rotary motion of the drive shaft is transmitted to the input coupling device and via this to the first rotary valve or its rotary slide. The described configuration of the valve assembly allows for a particularly flexible arrangement of the rotary valves relative to each other.

[0027] Another embodiment of the invention provides that the first coupling device is at least temporarily coupled to the drive shaft and / or the input coupling device of the freewheel, and the second coupling device is permanently coupled to an output coupling device of the freewheel. This means that the second rotary valve is permanently coupled to the freewheel, but the freewheel is not necessarily permanently connected to the drive shaft and / or the first rotary valve. For example, it may be provided that the freewheel is only temporarily driven on the input side via the drive shaft by the actuator, particularly while the actuator is being used to drive the first rotary valve.

[0028] This means that the rotary motion of the drive shaft, which is directed towards driving the first rotary valve, is not continuous, but only intermittent, serving to drive the freewheel on the input side. For example, the first coupling side and / or the input coupling device are designed accordingly. If the first coupling device and / or the input coupling device are designed as or have a toothed connection, the toothing can be interrupted to drive the freewheel only intermittently. This allows for particularly flexible operation of the fluid power valve system.

[0029] Finally, in a further preferred embodiment of the invention, the first coupling device, the second coupling device, the input coupling device, and the output coupling device each have or are designed as toothing. At least one of the following devices is designed as or has toothing: first coupling device, second coupling device, input coupling device, and output coupling device. This applies only to those coupling devices that are actually present within the fluid power valve assembly. The use of toothing enables a particularly reliable coupling of the rotary valves to the drive shaft.

[0030] The invention further relates to a method for operating a fluid power valve device, in particular a fluid power valve device according to the embodiments within the scope of this description.The fluid power valve assembly comprises a first rotary valve, a second rotary valve, and an actuator, each rotary valve having a rotary slide arranged in a rotary valve housing and driven by the actuator via a drive shaft, the first rotary valve being rigidly coupled to the drive shaft, and the actuator being used to set the first rotary valve to a first setpoint and the second rotary valve to a second setpoint, the second rotary valve being coupled to the drive shaft via a freewheel, the freewheel establishing a rigid connection between the drive shaft and the second rotary valve in a first direction of rotation of the drive shaft and decoupling the second rotary valve from the drive shaft in a second direction of rotation opposite to the first.It is also intended that the freewheel is directly coupled to the drive shaft.

[0031] The advantages of such a procedure or such a design of the fluid power system have already been mentioned. Both the fluid power valve system and the method for operating it can be further developed as described in this document, and reference is made to these details.

[0032] Another embodiment of the invention provides that the second rotary valve is first adjusted by rotating the drive shaft against one of the freewheel directions, and then the first rotary valve is adjusted by rotating the drive shaft in the freewheel direction. Each rotary valve is preferably continuously rotatable, meaning it can be rotated in at least one direction to adjust to the desired setpoint, particularly by more than 360°. This results in a particularly high degree of flexibility for the described method of operating the fluid power valve assembly. Specifically, it is possible to first adjust the second rotary valve to the second setpoint by rotating the drive shaft against the freewheel direction.

[0033] This means that the actuator drives both the first and second rotary valves, rotating them in the opposite direction to the freewheel direction. The freewheel direction refers to the direction of rotation in which the freewheel's output is decoupled from its input, meaning the second rotary valve is decoupled from the actuator and the drive shaft. Once the second rotary valve reaches the second setpoint, the first rotary valve is then adjusted to the first setpoint, if necessary, by rotating the drive shaft in the freewheel direction.

[0034] When the drive shaft is rotated in the free-running direction, only the first rotary valve is adjusted or rotated, not the second. The second rotary valve remains at its second setpoint. The drive shaft continues to rotate in the free-running direction until the first rotary valve is also set to its setpoint, namely the first setpoint. The independent rotation of the two rotary valves allows for particularly flexible adjustment of the fluid power valve assembly.

[0035] A further embodiment of the invention provides that, to adjust the second rotary valve to the second setpoint, the actuator is operated in such a way that the first rotary valve is alternately adjusted in opposite directions to values ​​deviating from the first setpoint until the second setpoint for the second rotary valve is reached. In this procedure, the first rotary valve is first adjusted to the first setpoint. The adjustment of the second rotary valve to the second setpoint only takes place subsequently. To adjust the second rotary valve to the second setpoint, after the first rotary valve has been adjusted to the first setpoint, the actuator rotates the drive shaft alternately in opposite directions, so that the first rotary valve also moves in opposite directions and is adjusted to values ​​deviating from the first setpoint.

[0036] Here, the drive shaft is alternately rotated in the freewheel direction and against it. When the drive shaft is rotated in the freewheel direction, the second rotary valve remains at its current setting. However, while the drive shaft is rotated against the freewheel direction, the second rotary valve is adjusted towards the second setpoint until it reaches that setpoint. The values ​​to which the first rotary valve is alternately set while the second rotary valve is being adjusted to the second setpoint are preferably selected such that the effective flow cross-sectional area of ​​the first rotary valve is not changed, or at most only changed slightly.

[0037] Preferably, the values ​​are chosen such that the flow cross-sectional area of ​​the first rotary valve remains constant while the second rotary valve is being adjusted to the second setpoint. If this is not possible, a deviation of the flow cross-sectional area of ​​at most 25%, at most 20%, at most 15%, at most 10%, or at most 5% of the flow cross-sectional area present at the first setpoint is permitted. With the described procedure, after the first rotary valve has been adjusted to the first setpoint, the second rotary valve is adjusted stepwise to the second setpoint. Accordingly, completely independent adjustment of the two rotary valves is possible.

[0038] The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing, without limiting the invention. The only embodiment shown is... Figure shows a schematic representation of a fluid power valve assembly with a first rotary valve and a second rotary valve, which are coupled to each other via a freewheel.

[0039] The figure shows a schematic representation of a fluid power valve assembly 1, comprising a first rotary valve 2 and a second rotary valve 3. Only an inlet 4 or 5, and a rotary valve 6 or 7, are shown for each of the rotary valves 2 and 3, with the rotary valves 6 and 7 depicted in a circumferentially rolled form. This means that only the outer surface of the rotary valves 6 and 7 is shown, extending over their entire circumference.

[0040] Rotary valve 6 has a control opening 8, and rotary valve 7 has a control opening 9. These can, in principle, be configured in any way. In the embodiment shown here, the control openings 8 and 9 have different shapes. However, they can also have the same shape. Depending on the overlap between the inlet 4 and the control opening 8 or between the inlet 5 and the control opening 9, a specific flow cross-section or cross-sectional area is set for the respective rotary valve 2 or 3. The greater the overlap between the inlet 4 and the control opening 8 or between the inlet 5 and the control opening 9, the larger the flow cross-section or cross-sectional area for the respective rotary valve 2 or 3.

[0041] The first rotary valve 2, or rather the rotary valve 6 of the first rotary valve 2, can be directly actuated by an actuator 10 via a drive shaft 11, which is coupled to the actuator 10 on one side and to the rotary valve 6 on the other. For example, the drive shaft 11 engages the rotary valve 6 via a toothed connection (not shown here). The first rotary valve 2, or rather its rotary valve 6, is thus rigidly coupled to the drive shaft 11. The second rotary valve 3, or rather its rotary valve 7, is only indirectly coupled to the drive shaft 11 via a freewheel 12.

[0042] In the embodiment shown here, the second rotary valve 3 is coupled to the first rotary valve 12 via the freewheel 12, and the first rotary valve 12 is coupled to the drive shaft 11 via the first rotary valve 3. An arrow 13 indicates the freewheel direction of the freewheel 12, and an arrow 14 indicates the opposite direction of rotation. Due to the freewheel 12 between the rotary valves 2 and 3, only a rotational movement of the first rotary valve 2 opposite to the freewheel direction of the freewheel 12 is transmitted to the second rotary valve 3. A rotational movement of the first rotary valve 2 in the freewheel direction does not cause any rotational movement of the rotary valve 3, so that the latter remains stationary.

[0043] To couple the rotary valves 2 and 3 to the freewheel 12, the first rotary valve 2 has a first coupling device 15 and the second rotary valve 3 has a second coupling device 16. In the embodiment shown here, these are gear teeth. These are, for example, arranged offset from each other in the axial direction with respect to an axis of rotation of the freewheel 12. The coupling devices 15 and 16 can, in principle, be designed in any way, in particular in the form of shafts that connect the rotary valves 2 and 3, respectively, to the freewheel 12. Via the freewheel 12, the coupling devices 15 and 16 are connected to each other in such a way that, during a rotational movement of the coupling devices 15 and 16 relative to each other in one direction, they are coupled, and during a rotational movement in the opposite direction, they are decoupled from each other.The first coupling device 15 works together with an input coupling device 17 of the freewheel to couple the first rotary slide valve 2 with the freewheel 12.

[0044] To couple the freewheel 12 with the second rotary valve 3, the second coupling device 16 interacts with an output coupling device 18 of the freewheel 12. The coupling devices 17 and 18 are also, for example, in the form of gears. Accordingly, the gearing of the first coupling device 15 meshes with the gearing of the input coupling device 17, and the gearing of the second coupling device 16 meshes with the gearing of the output coupling device 18. The input coupling device 17 and the output coupling device 18 are connected to each other via a drive mechanism to implement the freewheel 12, such that a coupling exists during a rotational movement relative to each other in one direction. In the opposite direction, however, they are decoupled.

[0045] Particularly preferred in the operating procedure of the fluid power valve assembly 1 is the initial adjustment of the first rotary valve 2 to a first setpoint using the actuator 10. Subsequently, the second rotary valve 3 is adjusted to a second setpoint by alternately actuating the first rotary valve 2 in opposite directions using the actuator 10. This means that the first rotary valve 2 is alternately set to values ​​deviating from the first setpoint, thereby achieving a stepwise adjustment of the second rotary valve 3 towards the second setpoint. The values ​​deviating from the first setpoint are preferably selected such that the flow cross-sectional area of ​​the first rotary valve 2, as it exists at the first setpoint, is not changed or is changed only negligibly.

[0046] With the described design of the fluidic valve device and - preferably - the described operating method, a particularly flexible adjustment of the rotary valves 2 and 3 is possible, essentially independently of each other.

Claims

[1] Fluid power valve assembly (1) comprising a first rotary valve (2), a second rotary valve (3) and an actuator (10), wherein each of the rotary valves (2, 3) has a rotary valve (6, 7) arranged in a rotary valve housing and driven by the actuator (10) via a drive shaft (11), wherein the first rotary valve (2) is rigidly coupled to the drive shaft (11), wherein the second rotary valve (3) is coupled to the drive shaft (11) via a freewheel (12), wherein the freewheel (12) establishes a rigid connection between the drive shaft (11) and the second rotary valve (3) in a first direction of rotation of the drive shaft (11) and decouples the second rotary valve (3) from the drive shaft (11) in a second direction of rotation opposite to the first direction of rotation, characterized by , that the freewheel (12) is directly coupled to the drive shaft (11). [2] Fluid power valve device (1) according to claim 1, characterized by , that the first rotary valve (2) has a first coupling device (15) and the second rotary valve (3) has a second coupling device (16), wherein the first coupling device (15) and the second coupling device (16) are each coupled to the freewheel (12), wherein the first coupling device (15) is coupled to an input of the freewheel (12) directly coupled to the drive shaft (11) and the second coupling device (16) is coupled to an output of the freewheel (12). [3] Fluid power valve device (1) according to claim 2, characterized by , that the first coupling device (15) is coupled to the drive shaft (11) via an input coupling device (17) of the input of the freewheel (12). [4] Fluid power valve device (1) according to claim 2 or 3, characterized by, that the first coupling device (15) is at least temporarily directly coupled to the drive shaft (11) and / or the input coupling device (17) of the freewheel (12) and the second coupling device (16) is permanently directly coupled to an output coupling device (18) of the freewheel (12). [5] Fluid power valve device (1) according to one of claims 2 to 4, characterized by , that the first coupling device (15), the second coupling device (16), the input coupling device (17) and the output coupling device (18) each have a toothing or are designed as such. [6] Method for operating a fluid power valve assembly (1), in particular a fluid power assembly (1) according to one or more of the preceding claims, wherein the fluid power valve assembly (1) comprises a first rotary valve (2), a second rotary valve (3) and an actuator (10), wherein each of the rotary valves (2, 3) has a rotary slide (6, 7) arranged in a rotary valve housing and driven by the actuator (10) via a drive shaft (11), wherein the first rotary valve (2) is rigidly coupled to the drive shaft (11), and wherein the first rotary valve (2) is set to a first setpoint and the second rotary valve (3) to a second setpoint by means of the actuator (10), wherein the second rotary valve (3) is coupled to the drive shaft (11) via a freewheel (12).wherein the freewheel (12) establishes a rigid connection between the drive shaft (11) and the second rotary valve (3) in a first direction of rotation of the drive shaft (11) and decouples the second rotary valve (3) from the drive shaft (11) in a second direction of rotation opposite to the first direction of rotation, . characterized by , that the freewheel (12) is directly coupled to the drive shaft (11). [7] Method according to claim 6, characterized by , that first the adjustment of the second rotary valve (3) is carried out by turning the drive shaft (11) against a freewheel direction of the freewheel (12) and then the adjustment of the first rotary valve (2) is carried out by turning the drive shaft (11) in the freewheel direction. [8] Method according to any one of the preceding claims, characterized by, that to adjust the second rotary valve (3) to the second setpoint, the actuator (10) is operated in such a way that the first rotary valve (2) is alternately adjusted in opposite directions to values ​​deviating from the first setpoint, until the second setpoint for the second rotary valve (3) is reached.

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