Hydraulic actuator

Abstract

The invention relates to a hydraulic actuator (2) which is penetrated by a longitudinal axis (L), wherein its main valve spool (14), its pilot valve spool (16) and its actuator piston (18) are coaxial to each other.

Description

Technical Field

[0001] This invention relates to a hydraulic actuator and its operating method. Background Technology

[0002] Pilot-controlled hydraulic actuators are known in practice. However, their actuator pistons typically retract very slowly. In known hydraulic actuators, leakage at numerous leakage points must be minimized through complex design measures. Furthermore, known hydraulic actuators require a large installation space. Summary of the Invention

[0003] Therefore, the object of the present invention is to improve upon the prior art in this respect.

[0004] This objective is achieved by the hydraulic actuator and its operating method. Embodiments are the subject of this disclosure.

[0005] According to the present invention, a hydraulic actuator traversed by a longitudinal axis is provided, comprising: a housing having an inlet and an outlet; a first fluid path from the inlet to the outlet; a second fluid path from the inlet to the outlet; a main valve spool adjustable along the longitudinal axis between a single open position and / or a double open position and a closed position, wherein in the single open position, either the first or second fluid path is open and the other fluid path is closed, in the double open position, both the first and second fluid paths are open, and in the closed position, both the first and second fluid paths are closed; and a pilot valve spool coaxially arranged with the main valve spool and adjustable along the longitudinal axis between an open position and a closed position, wherein in the open position, the second fluid path is open, and in the closed position, the second fluid path is closed; and an actuator piston coaxially arranged with the main valve spool and adjustable along the longitudinal axis between a retracted position and an extended position by fluid pressure from the inlet.

[0006] The hydraulic actuator can be a parking lock or part of a parking lock.

[0007] Due to the coaxial design of the main valve slide, pilot valve slide, and actuator piston, this type of hydraulic actuator, which is pilot-controlled via the pilot valve slide, is very small, especially in terms of diameter. Coaxiality can refer to arrangement and / or adjustability. Through the interaction of the two valve slides and two fluid paths, the hydraulic actuator can present a variety of states and has a high degree of functionality.

[0008] The change in state can occur as follows. When the pilot valve slide moves to its closed position, the second fluid path closes (and the connection between the inlet and outlet of the second fluid path is broken), allowing the entire volumetric flow rate to flow through the first fluid path. This creates a higher pressure differential across the main valve slide, allowing it to move to its double-closed position. This effect can be amplified by the flow. In its double-closed position, the main valve slide closes both the first and second fluid paths. There is no connection between the inlet and outlet at this time. By closing both fluid paths, the fluid at the inlet can build up pressure to move the actuator piston from its retracted position to its extended position.

[0009] In its basic state, fluid can flow from the inlet through the hydraulic actuator to the outlet. The volumetric flow rate is distributed between two fluid paths. The volumetric flow rate can be controlled by the main valve spool and the pilot valve spool. The inlet and outlet are fluidly connected via fluid paths, preferably only via these two fluid paths. This reduces the space required for installation. As long as one of the valve spools is in the closed position, the fluid connection between the inlet and outlet along the corresponding fluid path is interrupted (the corresponding fluid path is completely closed), and due to leakage, the volumetric flow rate in the corresponding fluid path is zero or approximately zero.

[0010] When the main valve spool is in its open position, the corresponding fluid path at the main valve spool is open. When the main valve spool is in its closed position, the corresponding fluid path at the main valve spool is closed, and the volumetric flow rate in the corresponding fluid path is zero or approximately zero due to leakage. The main valve spool can (only) move into (up to the closed position) and out of the first fluid path. The main valve spool can move into (up to the closed position) and out of the first and second fluid paths. If the fluid path is closed by one of the two valve spools and open by the other, the entire fluid path can be described as partially open. It is conceivable that the main valve spool is designed and / or arranged such that it can be forced into its closed position and / or fixed there by the fluid pressure at the inlet or in the first valve chamber. It is conceivable that the main valve spool has a closed position pressure surface. The closed position pressure surface can be exposed to the fluid pressure present at the inlet or in the first valve chamber. This enables rapid adjustment, preferably from a pre-closed position to the closed position. It is conceivable that the closed position pressure surface restricts the first valve chamber in the closed position of the main valve spool. This allows the closed position to be fixed. When the main valve slide valve is in the closed position, the pressure applied to the closed position pressure surface can fix the main valve slide valve in its closed position.

[0011] If the pilot valve spool is in its open position, the corresponding fluid path at the pilot valve spool is open. If the pilot valve spool is in its closed position, the corresponding fluid path at the pilot valve spool is closed, and due to leakage, the volumetric flow rate in the corresponding fluid path is zero or approximately zero. The pilot valve spool can (only) move into the second fluid path (up to the closed position) and then move out of it.

[0012] The first fluid path differs from the second fluid path. It is conceivable that the first fluid path extends from the inlet into the first valve chamber and / or into the third valve chamber, and then to the outlet. It is conceivable that the second fluid path extends from the inlet into the first valve chamber (or the first valve chamber) and / or into the second valve chamber and / or into the third valve chamber (or the third valve chamber), and then to the outlet. The use of a shared chamber reduces the space required for installation. The inlet can be connected to the first valve chamber, preferably directly, to reduce the space required for installation. The outlet can be connected to the third valve chamber, preferably directly, to reduce the space required for installation. The first valve chamber can be fluidly connected to the second valve chamber via a first fluid opening. The second valve chamber can be fluidly connected to the third valve chamber via a second fluid opening. The first valve chamber can be fluidly connected to the third valve chamber via a control edge. All these designs result in a compact structure.

[0013] The housing can be the enclosure of a hydraulic actuator. The housing may contain an electromagnet. The electromagnet may be a linear magnet. The electromagnet and / or armature and / or armature rod may be coaxial with the main valve spool. The armature and / or armature rod may be adjustable along the longitudinal axis. This reduces the space required for installation. The armature rod may be attached to the armature and is therefore adjustable. The electromagnet may be located at or form the front end of the housing. Hydraulic actuators may include electromagnets.

[0014] The pilot valve spool can be biased to one of its positions, preferably the open position, by a pilot valve spool spring. The pilot valve spool can be connected to or removed from the armature and / or armature rod. Therefore, it can be adjusted to one of its positions, preferably the closed position. The pilot valve spool and the main valve spool spring can be separate components. The pilot valve spool spring can bias the armature and / or armature rod to the de-energized position; preferably, the armature and / or armature rod extends when the electromagnet is de-energized. When energized, the armature and / or armature rod can move into the coil of the electromagnet. Since the pilot valve spool spring can take over the function of the armature spring, a dedicated armature spring is not required, thus reducing the number of components. The pilot valve spool and the main valve spool are separate components and / or can be adjusted independently of each other.

[0015] The main valve spool can be biased to one of its positions by the main valve spool spring, preferably to its single open position. The pilot valve spool can be connected to the armature and / or armature rod so that it can be adjusted to one of its positions, preferably to its closed position.

[0016] The actuator piston can be biased to one of its positions by an actuator piston spring, preferably to its retracted position. The actuator piston may have a pressure surface exposed to the fluid present at the inlet, preferably defining a first valve chamber. This allows it to be rapidly adjustable. In its retracted position, the actuator piston retracts into the housing. In its extended position, the actuator piston extends out of the housing.

[0017] According to further development, it can be specified that the actuator piston abuts against the main valve slide valve in its contracted position, thereby moving it to a pre-closed position within its single-open and / or double-open positions; preferably, in the pre-closed position, the volumetric flow rate of the first fluid path is greater than the volumetric flow rate of the second fluid path, preferably due to the pre-closed position.

[0018] The actuator piston defines a (first) main valve spool stop due to its contact with the main valve spool. Therefore, in its retracted position, the actuator piston can engage with the main valve spool in one of its two open positions. This contact can be a floating connection. The actuator piston and / or the main valve spool can each have contact surfaces facing each other, preferably extending perpendicular to the longitudinal axis. This prevents lateral forces.

[0019] It is conceivable that the contact position can be spring-biased, preferably by a main valve spool spring or an actuator piston spring, or more preferably by a main valve spool spring and an actuator piston spring acting in opposite directions. It is conceivable that the actuator piston spring is stronger than the main valve spool spring. It is conceivable that the force balance between the actuator piston spring and the main valve spool spring defines the contact position and / or the pre-closed position.

[0020] It can be envisioned that the actuator piston, in its extended position, does not abut against the main valve slide or is axially spaced from it. This increases the stroke of the actuator piston and enables the main valve slide to perform additional functions.

[0021] The pre-closed position is used to reduce positioning time. The pre-closed position can be a position of the main valve slide valve from which it can be forced into its closed position due to the fluid pressure at the inlet or in the first fluid path, or the pressure difference across the main valve slide valve. The pressure difference may stem from the fact that the volumetric flow rate of the first fluid path is greater than that of the second fluid path.

[0022] The pre-closed position or (first) main valve spool stop can be a component of a flip-flop valve. The flip-flop valve can be used to control the actuator piston. Due to the contact between the actuator piston and the main valve spool, a connection exists between the actuator piston and the main valve spool, resulting in the flip-flop valve being activated / only when the actuator piston is in the retracted position. It is conceivable that the pre-closed position and / or contact allow the flip-flop valve to be activated.

[0023] Based on further development, the hydraulic actuator may be specified to include a locking mechanism, which includes:

[0024] - The driving element, preferably a conical element or cone, is preferably arranged on the pilot valve spool.

[0025] - At least one locking receiving portion, preferably the at least one locking receiving portion, preferably two locking receiving portions, are arranged on the actuator piston, and

[0026] - At least one locking element, preferably a ball, wherein the locking element can be driven into the locking receptacle by a drive element to lock the actuator piston in the axial direction.

[0027] The hydraulic actuator may have at least one locking element, and the actuator piston may have a first locking receptacle and a second locking receptacle. Each locking receptacle may be assigned one locking element. The actuator piston may be secured by the retaining interaction of at least one locking element with one of the corresponding locking receptacles. This allows the actuator piston to be easily locked in the axial direction. In the driven position, at least one locking element may be simultaneously arranged in a fixed locking opening and a corresponding locking receptacle that is substantially movable in the longitudinal direction. The actuator piston is locked in the axial direction because the drive element prevents the locking element from escaping from the locking receptacle.

[0028] It is conceivable that each locking receptacle has an ejection ramp. On the one hand, this can be used to bring out the corresponding locking element from the locking receptacle during longitudinal adjustment of the locking receptacle while the driving element is in the non-driven position.

[0029] It is conceivable that the locking element can be pushed into either the first locking receiver or the second locking receiver. This allows the number of locking elements to remain relatively small. It is conceivable that pushing the locking element into the first locking receiver locks the actuator piston in its retracted position. It is conceivable that pushing the locking element into the second locking receiver locks the actuator piston in its extended position.

[0030] The drive element can be arranged along the longitudinal axis and / or coaxially with the main valve slide valve, and can be adjusted between a driven position and a non-driven position. In the driven position, the locking element is pushed into the corresponding locking receiving portion; in the non-driven position, the locking element can be released from the corresponding locking receiving portion. In the driven position, the actuator piston can be locked in the axial direction. In the non-driven position, the actuator piston can be unlocked in the axial direction or can move longitudinally.

[0031] The drive element can be securely connected to and / or integrated with the armature and / or armature rod and / or pilot valve slide of the electromagnet. Alternatively, it can be a separate component. The drive element can then be adjusted between the driven and non-driven positions by adjusting the armature and / or armature rod and / or pilot valve slide. Time-sensitive locking of the actuator piston can now be performed quickly and reliably. The connection between the drive element and, in particular, the pilot valve slide means that both are relatively stationary relative to each other. This creates an advantageous connection between the pilot valve function and the locking function. Therefore, separate locking and unlocking are not required.

[0032] It is conceivable that the pilot valve spool and the actuating element are designed and / or arranged such that the opening position of the pilot valve spool and the actuating position of the actuating element are simultaneous. This connection can be achieved, in particular, through the design described above.

[0033] It is conceivable that the pilot valve spool and the actuating element are designed and / or arranged such that the closed position of the pilot valve spool and the non-driven position of the actuating element are given simultaneously. This connection is particularly achieved through the embodiments described above.

[0034] The drive element is specifically designed to press at least one locking element radially outward into the locking receptacle of the piston (drive position) or not to press it radially outward (non-drive position) depending on its position. When the drive element is in the appropriate position, this achieves locking of the actuator piston.

[0035] As further developed, the hydraulic actuator may be specified to include an electromagnet capable of adjusting a pilot valve spool along a longitudinal axis; preferably, the pilot valve spool is connected to an armature or armature rod, preferably in a fixed manner. The connection may be a form fit, a force fit, or a material fit, or a combination thereof. An integrated design of the pilot valve spool and the armature or armature rod is conceivable.

[0036] Since both the pilot valve slide and the drive element can be connected to the armature and / or armature rod, both can be regulated by an electromagnet. It is conceivable that when the solenoid coil of the electromagnet is de-energized, the pilot valve slide is in its open position. This allows for free fluid connection between the inlet and outlet in the event of a power outage. This is particularly advantageous in fluid systems where the hydraulic actuator is arranged in a conventional flow path.

[0037] It is conceivable that a (first) compensation channel is formed between the armature and the armature rod. It is conceivable that a (second) compensation channel is formed between the armature rod and the pilot valve slide and / or drive element. The channels can extend in the axial direction. Fluid can flow through the corresponding compensation channels during regulation, thereby reducing resistance and increasing the regulation speed.

[0038] As further developed, the hydraulic actuator can be specified to include a control edge that can regulate the volumetric flow rate of a first fluid path using a main valve spool. The control edge can also be used to close the first fluid path. It is conceivable that the main valve spool, in its pre-closed position, is pressurized in the direction of the control edge through contact with the actuator piston. The control edge can be formed by a housing and / or an insert inserted into the housing. This allows for a compact design.

[0039] With further development, the hydraulic actuator can be specified to include an inner wall, preferably an inner sleeve, within the housing, wherein the inner wall can guide the main valve spool. The inner wall may have guide surfaces for the main valve spool on either the inner or outer circumferential side. This guidance reduces the number of components and the space required for installation. The inner sleeve may be a hollow cylinder.

[0040] The inner wall may have a (second) main valve spool stop. It is conceivable that the main valve spool abuts against the (second) main valve spool stop in its single-open position. For space reduction reasons, it is conceivable that two different stops are formed for the main valve spool in the axial direction. The first of these stops may be a (first) main valve spool stop on the actuator piston. The second of these stops may be a (second) main valve spool stop on the inner wall or housing. It is conceivable that the main valve spool abuts against the stop depending on the position of the actuator piston. If the actuator piston is in its retracted position, it is conceivable that the main valve spool can only abut against the (first) main valve spool stop on the actuator piston. If the actuator piston is in its extended position, it is conceivable that the main valve spool can only abut against the (second) main valve spool stop on the inner wall or housing.

[0041] It can be envisioned that the hydraulic actuator can be moved to the fully open position, where the fluid flow from inlet to outlet is maximized and flow resistance is minimized. It can be envisioned that the main valve spool, in its single or double open position, achieves the fully open position. It can be envisioned that in the fully open position, the pilot valve spool is in its open position. This reduces flow resistance.

[0042] It is conceivable that the main valve spool, preferably in its single-closed position and / or fully open position, closes the first fluid opening and thereby closes the second fluid path. The entire volumetric flow rate can then / must flow through the first fluid path. This has the advantage of reducing the amount of contaminants entering via the pilot valve spool. Furthermore, it saves installation space.

[0043] The inner wall can form a support surface for one / the main valve slide spring. This surface reduces the number of parts and the space required for installation.

[0044] The inner wall can guide the pilot valve spool. The inner wall can have guide surfaces for the pilot valve spool on either the inner or outer circumferential side. This guidance reduces the number of components and the space required for installation. It is conceivable and advantageous that the pilot valve spool is guided on the inner circumferential side of the inner wall, while the main valve spool is guided on the outer circumferential side (or vice versa). The stroke distances of the pilot valve spool and the main valve spool can overlap in the radial direction. This enables a compact design.

[0045] The inner wall can form a support surface for one or more pilot valve spool springs. This surface reduces the number of parts and the space required for installation.

[0046] The inner wall can guide the actuator piston. The inner wall can have guide surfaces for the actuator piston on either the inner or outer circumferential side. This guidance reduces the number of components and the space required for installation. It is conceivable and advantageous that the actuator piston and the main valve slide valve are guided on the same side of the inner wall (either the inner or outer circumferential side), preferably the outer circumferential side. This allows the actuator piston to be compactly mounted on the main valve slide valve.

[0047] The inner wall may have a retraction stop for the actuator piston. The retraction stop may be the front end of the inner wall, thus achieving a compact design. It is conceivable that the actuator piston abuts against the retraction stop in its retracted position. It is conceivable that the contact between the actuator piston and the retraction stop defines the contact position and / or the pre-closed position.

[0048] The inner wall may have a first fluid opening that guides a second fluid path and can be closed and opened by a main valve spool and / or a pilot valve spool. The first fluid opening guides the second fluid path from the outer circumferential side of the inner wall to the inner circumferential side. Advantageously, the first fluid opening can be closed by two valve spools, which is equivalent to cutting off the fluid connection between the inlet and outlet via the second fluid path. This design is used to create a compact yet highly functional hydraulic actuator. The first fluid opening can be closed in the closed position of the pilot valve spool. The first fluid opening can be closed in the single open position of the main valve spool. The first fluid opening can be open when the pilot valve spool is in its open position and the main valve spool is in its double open position or its closed position.

[0049] The inner wall may have a second fluid opening that guides a second fluid path and can be (preferably only) closed and opened by the main valve slide valve.

[0050] The second fluid opening guides the second fluid path from the inner circumferential side of the inner wall to the outer circumferential side. This enables a compact design. Advantageously, the second fluid opening can only be closed by the main valve spool, which is equivalent to cutting off the fluid connection between the inlet and outlet via the second fluid path. This design results in a compact yet highly functional hydraulic actuator. The second fluid opening can be closed when the main valve spool is in the closed position. The second fluid opening can be open when the main valve spool is in its single open position and when it is in its double open position.

[0051] However, if the first fluid opening is open and the main valve slide is in its closed position, the second fluid path remains closed by the main valve slide, preventing a decrease in fluid pressure at the actuator piston. The actuator piston can be locked in this state. Locking is thus decoupled from hydraulic control. Complete separation of the fluid connection between the inlet and outlet is maintained, even if the pilot valve slide opens the first fluid opening. This circuit can be referred to as the triggering circuit of the trigger valve.

[0052] The inner wall may have a locking opening in which a locking mechanism is housed. The locking opening may be oriented radially. The locking opening can be used to accommodate a locking element. Each locking opening may be assigned one locking element. Depending on its radial position, a drive element can push the locking element outward through the corresponding locking opening into the corresponding locking receiver. This also enables a compact design.

[0053] The inner wall and / or the main valve slide valve can create a separation between the first fluid path and the second fluid path. This enables a compact design.

[0054] The inner wall can guide a second fluid path on the inner circumferential side, preferably from the first fluid opening to the second fluid opening. This enables a compact design.

[0055] Except for any fluid openings, the inner wall may not have undercuts in the longitudinal direction. This enables cost-effective production, especially in the case of an integrated design with the shell.

[0056] The inner wall can be open to the actuator piston at one end. This allows for fluid connection from the outer circumference of the inner wall to the inner circumference via a (third) compensation channel. The compensation channel increases the regulating speed.

[0057] The first fluid opening can be positioned upstream of the second fluid path leading to the second fluid opening. This allows for a compact design.

[0058] The armature rod can extend within the inner wall and / or be arranged in the second fluid path. The pilot valve spring can extend within the inner wall and / or be arranged in the second fluid path. Both enable a compact design.

[0059] Based on further development, the shell-guided main valve slide valve can be specified.

[0060] The housing may have guide surfaces on its inner circumferential side for the main valve slide. This guidance reduces the number of components and the space required for installation. It is conceivable that the housing is designed such that guidance through the housing occurs only in the closed position of the main valve slide. This allows for direct guidance of a second fluid path through the housing. It is conceivable that the housing is designed such that guidance through the housing closes the second fluid path. For example, the main valve slide may slide past a control edge, thereby closing the second fluid path at the control edge. Alternatively, an insert may guide the main valve slide.

[0061] The housing guides the pilot valve spool. The housing may have guide surfaces on its inner circumferential side for the pilot valve spool. This guidance reduces the number of components and the space required for installation.

[0062] The housing can guide the actuator piston. The housing may have guide surfaces on its inner circumferential side for the actuator piston. These guides reduce the number of components and the space required for installation.

[0063] The housing may have at least one main valve spool stop for the main valve spool. It is conceivable that the housing forms one (second) main valve spool stop and / or one (third) main valve spool stop. It is conceivable that the main valve spool abuts against the (second) main valve spool stop in its single-open position. It is conceivable that the main valve spool abuts against the (third) main valve spool stop in its closed position. The second and third main valve spool stops may be arranged facing each other and / or defining the ends of the main valve spool's stroke range. It is conceivable that a first main valve spool stop is formed along the longitudinal axis between the second and third main valve spool stops. This is for achieving a compact design and can be used to implement a trigger valve.

[0064] The housing can form a support surface for one / the main valve slide spring. This surface reduces the number of parts and the space required for installation.

[0065] The housing can form a support surface for one / the pilot valve spool spring. This surface reduces the number of parts and the required installation space.

[0066] The housing can form a support surface for one or more actuator piston springs. This surface reduces the number of parts and the required installation space.

[0067] The housing can have inlets and outlets that are adjacent to each other along the longitudinal axis or aligned in the axial direction. The inlets and outlets are therefore on the same side, which allows for short fluid paths and low space requirements.

[0068] The housing may have or form a first valve chamber and / or a second valve chamber and / or a third valve chamber. It is conceivable that the first valve chamber is fluidly connected to the second and third valve chambers, preferably directly. It is conceivable that the second valve chamber is fluidly connected to the third valve chamber, preferably directly. In particular, direct connection results in a compact design. It is conceivable that a control edge separates the first and third valve chambers.

[0069] It can be envisioned that the first valve chamber is defined on the outward circumferential side by the housing and / or on the inward circumferential side by the inner wall and / or the main valve slide and / or the pressure surface of one of the actuator pistons. This allows the fluid to act directly on the pressure surface of the actuator piston after entering through the inlet. Therefore, deep penetration of fluid pressure is avoided.

[0070] It is conceivable that the second valve chamber is formed within the inner wall. The second valve chamber may be defined by the inner wall on its outward circumferential side. The second valve chamber may be axially defined at one end by the support surface of the pilot valve spring and / or at the other end by the pilot valve spool. This is to reduce the space required for installation.

[0071] It can be envisioned that the third valve chamber is defined on the outward circumferential side by the housing and / or on the inner circumferential side by the inner wall and / or the main valve slide valve.

[0072] It is conceivable that the inner wall or inner sleeve is integrally molded with the outer shell. This reduces the number of parts.

[0073] The housing may have a retraction stop for the actuator piston. It is conceivable that the actuator piston abuts against the retraction stop in its retracted position. It is conceivable that the contact between the actuator piston and the retraction stop defines the contact position and / or the pre-closed position. It is conceivable that only one of the inner wall and the housing has a retraction stop.

[0074] As further developed, the actuator piston may be specified to have a sleeve portion. The sleeve portion may be axially formed at one end and / or guided on the inner wall or housing. Preferably, the sleeve portion is guided on the outer circumferential side of the inner wall.

[0075] The actuator piston or sleeve portion may have at least one flow opening that can guide a second fluid path. This design is intended to allow fluid to flow along the second fluid path when the main valve slide is in the closed position.

[0076] The actuator piston may have a disc portion. The disc portion may be sealed in the longitudinal direction and may seal the interior of the hydraulic actuator relative to the hydraulic actuator environment. A sleeve portion may be attached to the disc portion, resulting in a compact design. The disc portion may form one / the pressure surface of the actuator piston. The disc portion may be guided on the inner circumferential side of the housing.

[0077] The actuator piston or sleeve portion may have at least one locking receptacle on the inner circumferential side. This is also used to achieve a compact design, particularly in terms of diameter.

[0078] As further developed, the main valve slide valve can be specified to have a flow opening that guides a second fluid path. This design allows fluid to flow along the second fluid path when the main valve slide valve is in the contact position.

[0079] The main valve spool may have a stop flange. This allows the closed position and / or single open position of the main valve spool to be defined and secured. The stop flange may extend in the radial direction. The stop flange may abut against a second and / or a third main valve spool stop. This allows the stop flange to function as a double stop. It is conceivable that the stop flange has a pressure surface exposed to the fluid flowing into the inlet. This is used to rapidly move it from the pre-closed position to its closed position.

[0080] The main valve spool or stop flange may have a (fourth) compensation passage. Preferably, the (fourth) compensation passage extends in the longitudinal direction and / or can move with the main valve spool within the first valve chamber. The (fourth) compensation passage can be traversed by fluid displaced when the actuator piston moves to its retracted position. If the stop flange simultaneously abuts against the (second) main valve spool stop, fluid displacement would be impossible without the (fourth) compensation passage, or fluid displacement could cause the stop flange to rise from the (second) main valve spool stop. The (fourth) compensation passage can be fluid-permeable when the main valve spool is applied to the (second) main valve spool stop. The (fourth) compensation passage can be closed by the (third) main valve spool stop when the main valve spool is applied to the (third) main valve spool stop. This prevents leakage, allowing fluid pressure to be built up as quickly as possible to regulate the actuator piston when the main valve spool is in the closed position.

[0081] The main valve spool and pilot valve spool can be designed and / or arranged such that, in one operating state, the main valve spool closes the first and second fluid paths, while the pilot valve spool opens the second fluid path and / or simultaneously locks the actuator piston in its extended position. This operating state can occur when the electromagnet is de-energized and / or in the spring-loaded open position of the pilot valve spool and / or the locking mechanism. This allows the hydraulic actuator to be switched so that it remains closed even when the input signal is removed. This allows the actuator to reliably lock in the extended position when the input signal is removed.

[0082] The present invention also proposes an operating method. The hydraulic actuator operated in this manner can be the hydraulic actuator described in this disclosure. The operating method includes at least the following steps in a specified sequence. Assigning individual steps to operating states is merely for ease of understanding, but the division into operating states and their names is optional.

[0083] First state:

[0084] The hydraulic actuator is in its basic state, in which the first and second fluid paths are open and the actuator piston is in its retracted position. The main valve spool moves to its pre-closed position, where the volumetric flow rate of the first fluid path is greater than that of the second fluid path. Now, the following steps are performed from this basic state of the hydraulic actuator.

[0085] Second state:

[0086] The pilot valve slide valve moves from its open position to its closed position, thereby closing the second fluid path.

[0087] Third state:

[0088] The fluid pressure at the inlet moves the main valve slide valve to its closed position, thereby closing the first and second fluid paths.

[0089] Fourth state:

[0090] The actuator piston is moved to its extended position by the fluid pressure present at the inlet.

[0091] Fifth state:

[0092] The pilot valve slide valve moves from its closed position to its open position, thereby opening the second fluid path.

[0093] Sixth state:

[0094] The fluid pressure on the main valve slide valve is interrupted, and the main valve slide valve moves from its closed position to its single open position or double open position.

[0095] Seventh state:

[0096] Fluid flows from the inlet through the hydraulic actuator to the outlet along at least one of two fluid paths. In this state, the hydraulic actuator can be fully opened.

[0097] Eighth state:

[0098] The volumetric flow rate at the inlet is interrupted or reduced, and the pilot valve spool moves from its open position to its closed position, thereby shutting off the second fluid path. It is conceivable that reducing the volumetric flow rate would be sufficient, for example, if the hydraulic actuator is kept below the viscosity-related switching threshold of the main valve spool.

[0099] Ninth state:

[0100] The actuator piston moves to its retracted position, thereby moving the main valve spool to its pre-closed position. The basic state can then be restored. The first state can occur after the ninth state.

[0101] The advantages of hydraulic actuators described above also apply similarly to the operating method, and are cited here. Further developments in the operating method are described below by state classification.

[0102] First state:

[0103] The actuator piston can be locked in its retracted position by a locking device. The main valve spool can be axially spaced from its second main valve spool stop by abutting against the actuator piston (pre-locked position). The actuator piston spring presses the actuator piston against the main valve spool and / or the actuator piston can abut against the retracted stop. The volumetric flow rate from the inlet is divided into partial volumetric flow rates via the pilot valve spool or the first fluid path and the main valve spool or the second fluid path. The electromagnet is de-energized.

[0104] The electromagnet can be de-energized. The main valve slide can be in the pre-closed position. The pilot valve slide can be in the open position. The drive element can be in the driven position. The actuator piston can be in the retracted position. The first fluid path can be fully open from inlet to outlet. The second fluid path can be fully open from inlet to outlet. Volumetric flow rate can exist at the inlet.

[0105] Second state:

[0106] The drive element, which can be coupled to the pilot valve spool, can be moved to a non-driven position. This can be accomplished, for example, by energizing the electromagnet and / or resisting the force of the pilot valve spring. The actuator piston can thus move longitudinally. Simultaneously, the first fluid opening can be closed by the pilot valve spool, allowing the entire volumetric flow rate to be directed via the main valve spool or through the first fluid path. Due to the higher pressure difference generated across the main valve spool and the higher flow force at the control edge of the main valve spool, the latter can be closed against the force of the main valve spool spring.

[0107] The electromagnet can be energized. The main valve slide can remain in the pre-closed position. The pilot valve slide can move to the closed position, preferably by energizing the electromagnet. The drive element can move to the non-driven position, preferably by energizing the electromagnet. The actuator piston can remain in the retracted position. The first fluid path can remain fully open from inlet to outlet. The second fluid path can be closed by the pilot valve slide and is located at the pilot valve slide. Volumetric flow rate can be present at the inlet.

[0108] Third state:

[0109] Both fluid paths are closed. The connection between the inlet and outlet is thus completely blocked. However, it is conceivable that fluid pressure can still exist at the inlet and in the first valve chamber. This fluid pressure can push the main valve slide valve into its closed position. The electromagnet can remain energized.

[0110] The electromagnet can (continue to be) energized. The main valve slide can move into the closed position, preferably due to fluid pressure at the inlet and / or in the first valve chamber. The pilot valve slide can (continue to be) in the closed position, preferably due to the energization of the electromagnet. The drive element can (continue to be) in the non-driven position, preferably due to the energization of the electromagnet. The actuator piston can (continue to be) in the retracted position. The first fluid path can be closed by the main valve slide. The second fluid path can be closed by the pilot valve slide and / or by the main valve slide. Volumetric flow rate at the inlet can be present.

[0111] Fourth state:

[0112] With both fluid paths closed, the remaining volumetric flow rate at the inlet establishes fluid pressure, preferably in the first valve chamber. This pressure acts on the pressure surface of the actuator piston and can move the actuator piston to its extended position. The actuator piston can be moved against the force of the actuator piston spring. The electromagnet can remain energized.

[0113] The electromagnet can (continue) be energized. The main valve slide valve can (continue) be in the closed position, preferably due to fluid pressure at the inlet and / or in the first valve chamber. The pilot valve slide valve can (continue) be in the closed position, preferably due to the energization of the electromagnet. The drive element can (continue) be in the non-driven position, preferably due to the energization of the electromagnet. The actuator piston can be adjusted to the extended position, preferably due to fluid pressure at the inlet and / or in the first valve chamber. The first fluid path can be (continue) closed by the main valve slide valve. The second fluid path can be (continue) closed by the pilot valve slide valve and / or by the main valve slide valve. Volumetric flow rate at the inlet can be present.

[0114] Fifth state:

[0115] The actuator piston is moved to its extended position, and the drive element can be moved to its driven position. This is accomplished by de-energizing the electromagnet. The force of the pilot valve spring pushes the drive element into its driven position. The actuator piston is locked. The first fluid opening can be reopened by the pilot valve spool. However, the second fluid path can be partially open because the main valve spool simultaneously closes the second fluid opening in its closed position, and the first fluid path can still be closed by the main valve spool. The fluid pressure that may exist in the first valve chamber at the actuator piston cannot decrease. The fluid pressure that may exist in the first valve chamber pushes the main valve spool into its closed position. The locking of the actuator piston is thus decoupled from the hydraulic control. The fluid connection between the inlet and outlet remains closed even if the pilot valve spool reopens the first fluid port. This circuit can be described as a trigger circuit.

[0116] The electromagnet can be switched off. The main valve slide can (continue) be in the closed position, preferably due to fluid pressure at the inlet and / or in the first valve chamber. The pilot valve slide can move into the open position, preferably by the pilot valve slide spring. The drive element can move into the driven position, preferably by the pilot valve slide spring. The actuator piston can (continue) be in the extended position, preferably due to fluid pressure at the inlet and / or in the first valve chamber. The first fluid path can be (continued) closed by the main valve slide. The second fluid path can be (continued) opened by the pilot valve slide, but can be (continued) closed by the main valve slide, preferably at the second fluid opening. Volumetric flow rate at the inlet can be present.

[0117] Sixth state:

[0118] When the volumetric flow rate at the inlet is cut off, the main valve spool moves from its closed position by the spring force of the main valve spool spring, preferably into its single open position. Along its stroke path, the main valve spool can pass through the point where it is in the pre-closed position. Because the actuator piston is locked in its extended position, it cannot push the main valve spool into its pre-closed position. The main valve spool can then pass through the pre-closed position along its stroke path. The main valve spool can then abut against the second main valve spool stop, thereby opening the maximum flow cross-section. In this state, the fully open position of the hydraulic actuator can be achieved.

[0119] The electromagnet can be de-energized. The main valve slide can move into a single open position, preferably due to the cutoff or reduction of fluid pressure at the inlet and / or in the first valve chamber and / or the main valve slide spring. The pilot valve slide can remain in the open position, preferably due to the pilot valve slide spring. The drive element can remain in the driven position, preferably due to the pilot valve slide spring. The actuator piston can remain in the extended position, preferably due to the latch. The first fluid path can be opened by the main valve slide and fully opened from the inlet to the outlet. The second fluid path can be opened by the pilot valve slide and remains open at the pilot valve slide, but can be closed by the main valve slide and remains closed at the main valve slide, preferably at the first fluid opening. The volumetric flow rate at the inlet can be cut off or reduced.

[0120] Seventh state:

[0121] In the fully open position, there may be very low hydraulic resistance between the inlet and outlet. The main valve spool cannot move from this open position because the fluid pressure at the inlet, or the fluid pressure acting in the first valve chamber, or the main valve spool spring, presses the main valve spool into its (single) open position and prevents it from moving. Furthermore, the actuator piston cannot push the main valve spool out of the (single) open position because the actuator piston is locked in its extended position.

[0122] The electromagnet can remain de-energized. The main valve slide can remain in the single-open position, preferably due to the main valve slide spring. The pilot valve slide can remain in the open position, preferably due to the pilot valve slide spring. The drive element can remain in the driven position, preferably due to the pilot valve slide spring. The actuator piston can remain in the extended position, preferably due to the locking mechanism. The first fluid path can remain open by the main valve slide and be fully open from inlet to outlet. The second fluid path can remain open by the pilot valve slide, but can remain closed by the main valve slide, preferably at the first fluid opening. The volumetric flow rate at the inlet can be re-enabled or increased.

[0123] Eighth state:

[0124] The volumetric flow at the inlet can be cut off, and the actuator piston can be unlocked by adjusting the drive element to its non-driven position. This can be accomplished by energizing the electromagnet. When the actuator piston returns to the retracted position, the displaced fluid can flow through the fourth compensation channel and / or be pushed outward by the main valve spool. Due to the large opening cross-section of the main valve spool in this position, it is conceivable that it will not be closed. Furthermore, the hydraulic resistance when the actuator piston retracts can be very low. The actuator piston can abut against the main valve spool in its retracted position along its stroke path and carry it along its stroke path.

[0125] The electromagnet can be energized. The main valve slide can (continue) be in the single open position, preferably due to the main valve slide spring. The pilot valve slide can be moved to the closed position, preferably due to the energization of the electromagnet. The drive element can be moved to the non-drive position, preferably due to the energization of the electromagnet. The actuator piston can be released from its locked position. The first fluid path can be opened by the main valve slide (continue) and can be fully opened from inlet to outlet. The second fluid path can be closed by the pilot valve slide and can also be closed by the main valve slide and (continue) at the main valve slide, preferably each at the first fluid opening. The volumetric flow rate at the inlet can be cut off or reduced.

[0126] Ninth state:

[0127] The main valve slide can therefore be moved into its pre-closed position by the actuator piston. In the pre-closed position, the trigger circuit can be reactivated. It can be seen that the trigger circuit is activated and deactivated by the position of the actuator piston. When the actuator piston retracts to its retracted position, it pushes the main valve slide into its pre-closed position, and the trigger circuit can be activated. If the actuator piston extends to its extended position and is locked there, it is prevented from pushing the main valve slide into its pre-closed position, and the trigger circuit is deactivated / cannot be activated. The actuator piston can be locked again by the drive element. The default state is restored. The electromagnet can continue to be energized.

[0128] The electromagnet can (continue) be energized. The main valve slide can move into its pre-closed position, preferably due to contact with the actuator piston or its actuator piston spring. The pilot valve slide can (continue) be in the closed position, preferably due to the energization of the electromagnet. The drive element can (continue) be in the non-driven position, preferably due to the energization of the electromagnet. The actuator piston can move into the retracted position, preferably due to the actuator piston spring. The first fluid path can (continue) be opened by the main valve slide and fully opened from inlet to outlet. The second fluid path can be (continue) closed by the pilot valve slide, but can be opened by the main valve slide. Volumetric flow rate at the inlet can be present.

[0129] The hydraulic actuator can then enter a first state, for example, as follows: the electromagnet can be deactivated. The main valve spool can remain in the pre-closed position. The pilot valve spool can enter the open position, preferably via the pilot valve spool spring. The drive element can move into the drive position, preferably via the pilot valve spool spring. The actuator piston can remain in the retracted position, preferably due to the locking mechanism. The first fluid path can remain open by the main valve spool and be fully open from inlet to outlet. The second fluid path can be opened by the pilot valve spool and / or can remain open by the main valve spool and be fully open from inlet to outlet. The volumetric flow rate at the inlet can be cut off or reduced.

[0130] It should be noted that the components described herein are typically disclosed as separate components. An integrated design may be referenced.

[0131] If a component is disclosed multiple times, then embodiments and advantages described only for one component should also be considered as alternatives disclosed for other corresponding components. Axial and axial directions A operate parallel to the longitudinal axis. Radial and radial directions R operate perpendicular to the longitudinal axis. Circumferential and circumferential directions operate around the longitudinal axis. Attached Figure Description

[0132] Further features, details, and advantages of the invention can be found in the wording of the claims and in the following description of the embodiments with reference to the accompanying drawings, wherein:

[0133] Figure 1 The hydraulic actuator in its first state is shown.

[0134] Figure 2 The hydraulic actuator in the second state is shown.

[0135] Figure 3 The hydraulic actuator in the third state is shown.

[0136] Figure 4The hydraulic actuator in the fourth state is shown.

[0137] Figure 5 The hydraulic actuator in the fifth state is shown.

[0138] Figure 6 The hydraulic actuator in the sixth state is shown.

[0139] Figure 7 The hydraulic actuator in the seventh state is shown.

[0140] Figure 8 The hydraulic actuator in the eighth state is shown, and

[0141] Figure 9 The hydraulic actuator in the ninth state is shown.

[0142] List of reference numerals

[0143] 2. Hydraulic actuator

[0144] 4. Shell

[0145] 6 entrances

[0146] 8 Exports

[0147] 10 First Fluid Path

[0148] 12 Second Fluid Path

[0149] 14 Main valve slide valve

[0150] 16. Pilot valve / spool valve

[0151] 18 Actuator Piston

[0152] 20 cones

[0153] 22 ball bearings

[0154] 24 First locking receiving part

[0155] 26 Second locking receiving part

[0156] 28 Electromagnets

[0157] 30 Armature

[0158] 32 armature

[0159] 34 Control Edge

[0160] 36 Inner Sleeve

[0161] 38 Locking mechanism

[0162] 40 Shrinkage stop

[0163] 42 First fluid opening

[0164] 44 Second fluid opening

[0165] 46 Locking opening

[0166] 48 Sleeve section

[0167] 50 Flow opening

[0168] 52 Pressure Surface

[0169] 54 Main valve slide spring

[0170] 56 Pilot valve slide spring

[0171] 58 Actuator piston spring

[0172] 60 First main valve slide valve stop

[0173] 62 Second main valve slide valve stop

[0174] 64 Third main valve slide valve stop

[0175] 66 First Compensation Channel

[0176] 68 Second Compensation Channel

[0177] 70 Third Compensation Channel

[0178] 72 Support Surface

[0179] 74 Support Surface

[0180] 76 Support Surface

[0181] 78 discs

[0182] 80 Stop flange

[0183] 82. Produce the inclined plane.

[0184] 84. Fourth Compensation Channel

[0185] 86 coil

[0186] 88 Closed position pressure surface

[0187] Axial direction

[0188] A18 Extended Position

[0189] E18 Contraction Position

[0190] E20 Non-drive position

[0191] F14.1 Single Open Position

[0192] F14.2 Dual Open Position

[0193] F16 Open Location

[0194] L longitudinal axis

[0195] R radial direction

[0196] R1 First Valve Chamber

[0197] R2 Second Valve Chamber

[0198] R3 Third Valve Chamber

[0199] S14 Closed Position

[0200] S16 Closed Position

[0201] V volumetric flow rate

[0202] V14 Pre-close position

[0203] V20 drive location Detailed Implementation

[0204] In the accompanying drawings, identical or corresponding elements are designated by the same reference numerals and therefore are not described again unless necessary. To avoid repetition, features already described are not described again, and unless explicitly excluded, these features apply to all elements having the same or corresponding reference numerals. The disclosure contained throughout the specification can be analogously transferred to the same parts having the same reference numerals or the same part names. Positional information selected in the specification, such as upper, lower, side, etc., also refers to the drawings that are directly described and depicted, and should be analogously transferred to the new position if the position changes. Furthermore, individual features or combinations of features of the various embodiments shown and described may also represent independent, inventive, or innovative solutions.

[0205] Figures 1 to 9 A single hydraulic actuator 2 is shown in nine different and sequentially arranged states. For ease of understanding, the states in the accompanying drawings correspond to the states in the general description of the invention.

[0206] The hydraulic actuator 2 shown is structurally described as follows.

[0207] The hydraulic actuator 2 is traversed by the longitudinal axis L. The axial direction A extends along the longitudinal axis L. The radial direction R operates perpendicular to this axis.

[0208] The hydraulic actuator 2 includes a housing 4 with an inlet 6 and an outlet 8. The volumetric flow rate V is always present at the inlet 6.

[0209] The first fluid path 10 extends from the inlet 6 to the outlet 8, and the second fluid path 12 runs from the inlet 6 to the outlet 8.

[0210] The hydraulic actuator 2 includes a main valve spool 14, which is capable of being in a single open position F14.1 along the longitudinal axis L. Figures 6 to 8 The main valve slide valve 14 can also be adjusted to the double-open position F14.2. In this position, the first fluid path 10 is open and the second fluid path 12 is closed. Figure 1 , Figure 2 , Figure 9 At this position, both the first fluid path 10 and the second fluid path 12 are open. The main valve slide valve 14 can also be adjusted to the closed position S14. Figure 3 , Figure 4 , Figure 5 At this position, both the first fluid path 10 and the second fluid path 12 are closed. The main valve slide valve 14 includes a closed-position pressure surface 88.

[0211] The hydraulic actuator 2 includes a pilot valve spool 16, which is coaxially arranged with the main valve spool 14 and is adjustable along the longitudinal axis L to the open position F16. Figure 1 , Figures 5 to 7 At this position, the second fluid path 12 opens. The pilot valve spool 16 can be adjusted to the closed position S16. Figures 2 to 4 , Figure 8 , Figure 9 At this location, the second fluid path 12 is closed.

[0212] The hydraulic actuator 2 includes an actuator piston 18, which is coaxially arranged with the main valve spool 14 and can be moved along the longitudinal axis L to the retracted position E18 by fluid pressure from the inlet 6. Figures 1 to 3 , Figure 9 ) and the extended position A18 ( Figures 4 to 8 Adjust between )

[0213] The hydraulic actuator 2 includes a locking mechanism 38, which comprises a drive element in the form of a cone 20 on the pilot valve spool 16, two locking receptacles 24, 26 on the actuator piston 18, and two locking elements in the form of balls 22. The balls 22 can be driven by the cone 20 into the corresponding locking receptacles 24, 26. Figure 1 , Figures 5 to 7 The cone 20 can also be moved to the non-drive position E20 to lock the actuator piston 18 in the axial direction A. Figures 2 to 4 , Figure 8 , Figure 9 In this position, the ball 22 can be pushed out from the locking receiver 24, 26 by the push-out ramp 82 of the locking receiver.

[0214] The hydraulic actuator 2 includes an electromagnet 28 in the form of a linear magnet.

[0215] The electromagnet has a coil 86 that can be selectively energized, an armature 30, and an armature rod 32. The electromagnet 28, armature 30, and armature rod 32 are arranged coaxially with the main valve slide valve 14. The armature 30 and armature rod 32 are adjustable along the longitudinal axis L. A first compensation channel 66 is located between the armature 30 and the armature rod 32. A second compensation channel 68 is located between the armature rod 32 and the pilot valve slide valve. The electromagnet 28 forms the front end of the housing 4.

[0216] The control edge 34 is formed by the housing 4, which can regulate the volumetric flow rate of the first fluid path 10 using the main valve slide valve 14.

[0217] The hydraulic actuator 2 includes an inner wall in the form of a hollow cylindrical inner sleeve 36 within the housing 4. The inner sleeve 36 guides the main valve spool 14 and the actuator piston 18 via its outer circumferential side. The inner sleeve 36 guides the pilot valve spool 16 via its inner circumferential side. The inner sleeve 36 has a retraction stop 40 for the actuator piston 18 at one end. At the other end, the inner sleeve 36 is integrally incorporated into the housing 4. The inner sleeve 36 has a first fluid opening 42 that guides a second fluid path 12 and can be selectively closed and opened by the main valve spool 14 and the pilot valve spool 16. The inner sleeve 36 has a second fluid opening 44 that leads to the second fluid path 12 and can be selectively closed and opened by the main valve spool 14. The inner sleeve 36 has two locking openings 46 in which ball bearings 22 are received.

[0218] The housing 4 partially guides the main valve slide valve 14 along its travel path, i.e., when the main valve slide valve 14 has passed the control edge 34 ( Figures 3 to 5 The actuator piston 18 forms a first main valve slide stop 60, and the main valve slide 14 abuts against the first main valve slide stop 60 in its pre-closed position V14. Figure 1 The housing 4 forms a second main valve slide stop 62, and the main valve slide 14 abuts against the second main valve slide stop 62 in its single open position F14.1. Figures 6 to 8 The housing 4 forms a third main valve slide valve stop 64, and the main valve slide valve 14 abuts against the third main valve slide valve stop 64 in its double-open position. Figure 1 , Figure 2 , Figure 9The housing 4 forms a support surface 72 for the main valve spool spring 54. The main valve spool spring 54 tensions the main valve spool 14 in its single open position F14.1 or against the second main valve spool stop 62. The housing 4 forms a support surface 74 for the pilot valve spool spring 56. The pilot valve spool spring 56 biases the pilot valve spool 16 in its open position F16 and also biases the cone 20 in its driven position V20. The housing 4 forms a support surface 76 for the actuator piston spring 58. The actuator piston spring 58 biases the actuator piston 18 in its retracted position E18. The inlet 6 and outlet 8 are arranged adjacent to each other along the longitudinal axis L on the housing 4. A first valve chamber R1, a second valve chamber R2, and a third valve chamber R3 are formed in the housing.

[0219] The actuator piston 18 has a sleeve portion 48 and a disc portion 78. The disc portion 78 forms a pressure surface 52 exposed to the first valve chamber R1. On the inner circumferential side, the sleeve portion 48 has locking receiving portions 24, 26. In addition, the sleeve portion 48 has a third compensation channel 70.

[0220] The main valve spool 14 has a flow opening 50 that directs the second fluid path 12 to the first fluid opening 42. Furthermore, the main valve spool 14 has a stop flange 80 that abuts against a second main valve spool stop 62 and a third main valve spool stop 64. Additionally, the main valve spool 14 has a fourth compensation channel 84 within the stop flange 80.

[0221] The hydraulic actuator 2 shown is described in terms of function as follows.

[0222] Figure 1 The first state is shown. The hydraulic actuator 2 is in its basic state, in which the first fluid path 10 and the second fluid path 12 are open and the actuator piston 18 is in its retracted position E18. The actuator piston 18 is locked in its retracted position E18 by the locking mechanism 38. The main valve spool 14 abuts against the first main valve spool stop 60 and moves to its pre-closed position V14, in which the volumetric flow rate of the first fluid path 10 is greater than the volumetric flow rate of the second fluid path 12. The main valve spool 14 abuts against the actuator piston 16, thus axially spaced from its second main valve spool stop 62. The actuator piston spring 58 presses the actuator piston 18 against the main valve spool 14 and against the retracted stop 40. The hydraulic actuator 2 is in its basic state. In this state, the trigger circuit can be activated.

[0223] Figure 2The second state is shown. Coil 86 is energized, thereby attracting armature 30 and armature rod 32. The associated pilot valve spool 16 accordingly moves from its open position F16 to its closed position S16, where it closes the first fluid opening 42. The second fluid path 12 closes at the position of pilot valve spool 16. The entire volumetric flow rate V is thus guided either via main valve spool 14 or through the first fluid path 10. Due to the higher pressure difference generated across main valve spool 14 and the higher flow force at the control edge 34 of main valve spool 14, the latter can close against the force of main valve spool spring 54. When armature 30 is attracted, drive element / cone 20 moves into non-driven position E20.

[0224] Figure 3 The third state is shown. The pressure difference and the fluid pressure at inlet 6 cause the main valve slide valve 14 to move to its closed position S14 at the third main valve slide valve stop 64. This closes the first fluid path 10 and the second fluid path 12. The connection between inlet 6 and outlet 8 is thus completely blocked. Fluid pressure continues to exist in inlet 6 and the first valve chamber R1.

[0225] Figure 4 The fourth state is shown. The fluid pressure, unable to flow through the hydraulic actuator 2 due to the blockage to outlet 8, presses against the pressure surface 52 in the first valve chamber R1, pushing the actuator piston 18 into its extended position A18. The actuator piston 18 is moved against the force of the actuator piston spring 58.

[0226] Figure 5 The fifth state is shown. Actuator piston 18 is moved to its extended position A18. Electromagnet 28 is de-energized. Pilot valve spool 16 moves from its closed position S16 to its open position F16 via pilot valve spring 56. Pilot valve spool 16 opens the first fluid opening 42 and reopens the second fluid path 12 there. However, the second fluid path 12 is only partially open because the main spool valve 14 remains closed to the second fluid opening 44 and thus closes the second fluid path 12 there. The first fluid path 10 is also closed. When actuator piston 18 is adjusted, the drive element also moves to its driven position V20. Ball 22 is pressed into the second locking receiver 26. Actuator piston 18 is locked in place. The fluid pressure at actuator piston 18 cannot be reduced. The fluid pressure in the first valve chamber R1 pushes the main valve spool 14 into its closed position S14. The locking of actuator piston 18 is decoupled from hydraulic control. The fluid connection between inlet 6 and outlet 8 remains closed even if pilot valve spool 16 reopens the first fluid opening 42. This circuit can be described as a trigger circuit. The trigger circuit is deactivated when actuator piston A is locked in the extended position A18, preferably after a brief interruption or reduction in volumetric flow rate V.

[0227] Figure 6The sixth state is shown. The fluid pressure on the main valve slide 14 can now be interrupted. This can be done by cutting off the volumetric flow rate V at inlet 6. The elimination of the fluid pressure in the first valve chamber R1, which ensures the closed position, causes the spring force of the main valve slide spring 54 to move the main valve slide 14 out of its closed position S14. In this case, regulation is performed in its single open position F14.1. Along its stroke path, the main valve slide 14 passes the point where it is located in the pre-closed position V14. The stroke path of the main valve slide 14 ends at the second main valve stop 62. This opens the maximum flow cross-section.

[0228] Figure 7 The seventh state is shown. The main valve spool 14 opens the first fluid path 10 at the second main valve spool stop 62. Fluid flows along the first fluid path 10 from inlet 6 through the hydraulic actuator to outlet 8. In this state, the hydraulic actuator 2 is fully open. If the hydraulic actuator 2 is a parking lock, the seventh state can occur when the vehicle is in driving mode. In the fully open position, there may be very little hydraulic resistance between inlet 6 and outlet 8. The main valve spool 14 cannot move from this single-open position F14.1 because the fluid pressure at inlet 6, the additional fluid pressure acting in the first valve chamber R1, and the main valve spool spring 54 press the main valve spool 14 into its single-open position F14.1 and prevent it from moving out of this position. Furthermore, the actuator piston 18 cannot push the main valve spool 14 out of the single-open position 14.1 because the actuator piston 18 is locked in its extended position A18.

[0229] Figure 8 The eighth state is shown. The electromagnet is energized. This moves the pilot valve spool 16 to its closed position S16 and simultaneously moves the drive element / cone 20 to its non-driven position E20. The actuator piston 18 is unlocked and can be adjusted longitudinally. The fluid pressure on the main valve spool 14 is interrupted. This can be done by cutting off the volumetric flow rate V at inlet 6. The loss of fluid pressure in the first valve chamber R1 that ensures the open position results in a decrease in pressure on the pressure surface 52 of the actuator piston 18, and the actuator piston spring 58 pushes the unlocked actuator piston 18 into its retracted position E18. When the actuator piston 18 returns to the retracted position E18, the displaced fluid can flow through the fourth compensation channel 84 on one hand, and through the third compensation channel 70, the second compensation channel 68, and the second fluid opening 44 on the other. The fluid is also pushed out by the main valve spool 14 in the direction of outlet 8. During its stroke path, the actuator piston 18 contacts the main valve spool 14, which is in its retracted position E18, and resists the force of the main valve spool spring 54 to carry it along the stroke path. This lifts the main valve spool 14 from its contact with the second main valve spool stop 62.

[0230] Figure 9The ninth state is shown. The actuator piston 18 moves to its retracted position E18, thereby moving the main valve slide valve 14 to its pre-closed position V14. In the pre-closed position V14, the trigger circuit can be reactivated.

[0231] The energization of electromagnet 28 can be terminated. Pilot valve spool 16 moves from its closed position S16 to its open position F16 via pilot valve spring 56. Pilot valve spool 16 opens the first fluid opening 42 and reopens the second fluid path 12. The second fluid path 12 is now fully open because the main spool valve 14 is held in the pre-closed position V14 and the second fluid opening 44 is open. When the actuator piston 18 is adjusted, the drive element also moves to its driven position V20. Ball 22 is pressed into the first locking receiver 24. Actuator piston 18 is locked in place. The basic state is restored.

[0232] This invention is not limited to any of the embodiments described above, but can be modified in various ways. All features and advantages apparent from the claims, specification, and drawings, including structural details, spatial arrangements, and process steps, may be essential to this invention, either individually or in various combinations. This invention covers all combinations of at least two of the features disclosed in the specification, claims, and / or drawings. To avoid repetition, features disclosed relating to the apparatus should also be considered as disclosures relating to the process and should be claimable. Similarly, features disclosed relating to the process should be considered as disclosures relating to the apparatus and should be claimable.

Claims

1. A hydraulic actuator (2) having a longitudinal axis (L) passing through it, the hydraulic actuator (2) comprising: - A housing (4) having an inlet (6) and an outlet (8), - The first fluid path (10) from the inlet (6) to the outlet (8), - A second fluid path (12) from the inlet (6) to the outlet (8), - A main valve slide valve (14) adjustable along the longitudinal axis (L) between a single open position (F14.1) and / or a double open position (F14.2) and a closed position (S14), wherein in the single open position (F14.1), the first fluid path (10) or the second fluid path (12) is open and the other fluid path (10, 12) is closed; in the double open position (F14.2), the first fluid path (10) and the second fluid path (12) are open; and in the closed position (S14), the first fluid path (10) and the second fluid path (12) are closed. - A pilot valve slide valve (16), which is coaxial with the main valve slide valve (14) and adjustable along the longitudinal axis (L) between an open position (F16) and a closed position (S16), wherein in the open position (F16), the second fluid path (12) is open, and in the closed position (S16), the second fluid path (12) is closed, and - Actuator piston (18), which is coaxial with the main valve slide valve (14) and is adjustable along the longitudinal axis (L) by fluid pressure from the inlet (6) between a contracted position (E18) and an extended position (A18).

2. The hydraulic actuator (2) according to claim 1, characterized in that, The actuator piston (18) abuts against the main valve slide valve (14) in its retracted position (E18), thereby enabling the main valve slide valve (14) to move in its single open position (F14.1) and / or double open position (F14.2) to a pre-closed position (V14), preferably in the pre-closed position (V14), preferably due to the pre-closed position (V14), the volumetric flow rate of the first fluid path (10) is greater than the volumetric flow rate of the second fluid path (12).

3. The hydraulic actuator (2) according to any one of the preceding claims, characterized in that, A locking mechanism (38) is provided, the locking mechanism comprising: - Drive elements (24, 26), preferably tapered elements or cones (20) and / or preferably on the pilot valve spool (16), - At least one locking receiving portion (24, 26), preferably on the actuator piston (18), and - At least one locking element, preferably a ball (22), - Wherein, the locking element can be driven by the driving element into the locking receiving portion (24, 26) so as to lock the actuator piston (18) in the axial direction (A).

4. The hydraulic actuator (2) according to any one of the preceding claims, characterized in that, An electromagnet (28) is provided, which is capable of adjusting the pilot valve slide valve (16) along the longitudinal axis (L). Preferably, the pilot valve slide valve (16) is connected to the magnet armature (30) or the armature rod (32), and preferably is firmly connected to the magnet armature (30) or the armature rod (32).

5. The hydraulic actuator (2) according to any one of the preceding claims, characterized in that, A control edge (34) is provided, which is capable of adjusting the volumetric flow rate of the first fluid path (10) by means of the main valve slide valve (14).

6. The hydraulic actuator (2) according to any one of the preceding claims, characterized in that, The housing (4) has an inner wall, preferably an inner sleeve (36), wherein the inner wall... - Guide the main valve slide valve (14), and / or - Guide the pilot valve slide valve (16), and / or - Guide the actuator piston (18), and / or - Having a retraction stop (40) for the actuator piston (18), and / or - Having a first fluid opening (42) that guides the second fluid path (12) and can be closed and opened by the main valve slide valve (14) and / or the pilot valve slide valve (16), and / or - It has a second fluid opening (44) that leads to the second fluid path (12) and can be closed and opened by the main valve slide valve (14), and / or - It has at least one locking opening (46) in which a locking mechanism is housed.

7. The hydraulic actuator (2) according to any one of the preceding claims, characterized in that... The shell (4): - Guide the main valve slide valve (14), and / or - Having a main valve spool stop (62, 64) for the main valve spool (14), and / or - Forming a support surface (72) for the main valve slide spring (54), and / or - Forming a support surface (74) for the pilot valve slide spring (56), and / or - Forming a support surface (76) for the actuator piston spring (58), and / or - Having the inlet (6) and the outlet (8) adjacent to each other along the longitudinal axis (L), and / or - Having or forming a first valve chamber (R1) and / or a second valve chamber (R2) and / or a third valve chamber (R3), and / or - The inner wall or inner sleeve (36) is integrally formed.

8. The hydraulic actuator (2) according to any one of the preceding claims, characterized in that... The actuator piston (18): - Having a sleeve portion (48), and / or - Having a disk portion (78), and / or - It has at least one locking receiving portion (24, 26) on its inner circumferential side.

9. The hydraulic actuator (2) according to any one of the preceding claims, characterized in that... The main valve slide valve (14): - It has a flow opening (50) that can guide the second fluid path (12), and / or - Features a stop flange (80), and / or - It has a compensation channel (84).

10. An operating method for a hydraulic actuator (2), - Wherein, the hydraulic actuator (2) is designed according to any one of the preceding claims, The method includes the following steps starting from a basic state of the hydraulic actuator (2), in which a first fluid path (10) and a second fluid path (12) are open, the actuator piston (18) is in its retracted position (E18) and the main valve slide (14) is moved to its pre-closed position (V14), in which the volumetric flow rate of the first fluid path (10) is greater than the volumetric flow rate of the second fluid path (12). - Move the pilot valve slide valve (16) from its open position (F16) to its closed position (S16), thereby closing the second fluid path (12). - The main valve slide valve (14) is moved to its closed position (S14) by means of the fluid pressure present at the inlet (6), thereby closing the first fluid path (10) and the second fluid path (12). - The actuator piston (18) is moved to its extended position (A18) by means of the fluid pressure at the inlet (6). - Move the pilot valve slide valve (16) from its closed position (S16) to its open position (F16), thereby opening the second fluid path (12). - Interrupt the fluid pressure on the main valve slide valve (14) and move the main valve slide valve (14) from its closed position (S14) to its single open position (F14.1) or double open position (F14.2). - Allows fluid to flow from the inlet (6) to the outlet (8) via the hydraulic actuator (2) along at least one of two fluid paths (10, 12). - Interrupt or reduce the volumetric flow rate at the inlet (6) and move the pilot valve slide (16) from its open position (F16) to its closed position (S16), thereby closing the second fluid path (12). - Move the actuator piston (18) to its retracted position (E18) and thereby move the main valve slide valve (14) to its pre-closed position (V14).

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