Fluid pressure differential dependent flushing valve, fluid circuit and hydraulic arrangement with such a valve and use of such a valve

Abstract

The invention relates to a fluid pressure differential-dependent flushing valve device (1) with a first control piston (7), a second control piston (8), and a housing (2) with at least one fluid inlet opening (12, 13, 14), at least one fluid outlet opening (15), and a recess (6) for receiving the first control piston (7) and the second control piston (8). The first control piston (7) and / or the second control piston (8) are displaceable relative to the housing (2), and the first control piston (7) and the second control piston (8) are displaceable relative to each other.

Description

[0001] The invention relates to a valve device, in particular a fluid pressure differential-dependent flushing valve device.

[0002] The invention further relates to a fluid switching arrangement and a hydraulic switching arrangement with such a valve device. The invention further relates to the use of such a valve device.

[0003] Hydraulic actuators are used to operate a wide variety of devices. Consider, in particular, hydraulic pistons and, perhaps more importantly, hydraulic motors for operating various devices. In these examples, the pressure energy of a pressurized hydraulic fluid is converted into mechanical work. The pressurized fluid is usually supplied by one or more hydraulic pumps (with the pressurized fluid potentially being "temporarily stored" using hydraulic accumulators).

[0004] When the operation of a mechanically actuated device (driven device) is slowed down or stopped, inertial effects often occur. The (formerly) driven device then becomes a source of mechanical energy, which may be converted back into hydraulic energy (i.e., an increase in the hydraulic fluid pressure). Furthermore, it should be noted that the mechanically actuated device often needs to be actively decelerated (and not simply allowed to coast), so some form of braking is necessary. Moreover, it should be noted that rapid deceleration can be (and often is) a safety concern.To take just one example from a multitude of possibilities: A feed harvester must be stopped as quickly as possible if necessary to prevent foreign objects from entering the machine; a rotary mower must be stopped as quickly as possible if necessary to prevent injuries.

[0005] Understandably, wear-free braking systems are preferable to those subject to wear. It is not surprising that the idea of ​​utilizing the "hydraulic pumping effect" of the moving, previously mechanically actuated / actively driven device, so that the pumped, pressurized hydraulic fluid is used for wear-free braking, has been in use for several years.

[0006] To implement such "hydraulic braking," the hydraulic switching arrangement must be modified. During operating modes where a dedicated hydraulic pump drives the hydraulic actuator (such as a hydraulic motor), the hydraulic fluid return line from the actuator should have virtually no flow resistance to improve the actuator's efficiency and the overall energy efficiency of the arrangement. Conversely, in operating conditions where hydraulic braking of the driven device is required, a significant pressure build-up in the hydraulic fluid return line is necessary to ensure effective braking performance.

[0007] The current state-of-the-art approach involves the use of externally actuated fluid valves controlled by a control unit, typically an electronic controller. For example, the fluid return from a hydraulic motor can be selectively routed either to a direct fluid connection to a hydraulic fluid reservoir (low fluid flow resistance = flushing operating state of the circuit) or to a fluid path through an orifice that restricts the fluid flow (high fluid flow resistance, leading to pressure build-up and thus hydraulic braking). Depending on the design, either two actuated on / off valves or a single actuated directional control valve are typically used.

[0008] However, such a comparatively complex design also has its disadvantages. Not only is it more complex and requires more frequent and extensive maintenance, but a more complex design also carries a certain probability of sudden failures during operation. This could lead to a situation where emergency braking fails when needed. This could be due to an electrical fault or other reasons.

[0009] There is therefore still room for improvement. In particular, a simple circuit is desired that can switch between a "no fluid flow resistance mode" and a "fluid flow resistance mode"; preferably, only a single valve should be used for this task. Furthermore, for various reasons, it is desirable that the switching behavior of the respective valve be intrinsic, so that no external control (e.g., by an electronic controller) is required.

[0010] It is therefore an object of the present invention to propose a valve device which is improved compared to valve devices known from the prior art.

[0011] A further object of the present invention is to propose a fluid switching arrangement which is improved compared to fluid switching arrangements known in the prior art.

[0012] A further object of the present invention is to propose a hydraulic arrangement which is improved compared to hydraulic arrangements known from the prior art.

[0013] A further object of the present invention is to propose the use of a valve device which is improved compared to the use of valve devices known from the prior art.

[0014] A valve device, a fluid switching arrangement, a hydraulic arrangement and / or the use of a valve device according to the present disclosure solves at least one of these problems.

[0015] It is proposed to design a valve device, in particular a fluid pressure differential-dependent flushing valve device, comprising a first control piston, a second control piston, and a housing with at least one fluid inlet opening, at least one fluid outlet opening, and a recess for receiving the first and second control pistons, such that the valve device is designed and configured such that the first and / or the second control piston are displaceable relative to the housing. Furthermore, the valve device is configured such that the first and second control pistons are displaceable relative to each other. Typically, the valve device has a more or less pronounced elongated shape, with the pronounced elongated axis being referred to as the axial direction.The sliding movement of the first control piston and / or the second control piston in the recess of the housing typically comprises a linear / translational movement of the respective control piston relative to the housing, particularly in the axial direction. However, it is additionally or alternatively possible for the first control piston and / or the second control piston to perform a different movement, in particular a rotational movement, especially in a direction of rotation tangential to the axial direction. The recess for receiving the first control piston and / or the second control piston can be a common recess, for example, a more or less elongated recess. In particular, the recess can be substantially rotationally symmetrical, especially more or less cylindrical (at least with one or more substantially cylindrical sections).However, cross-sections other than rotationally symmetrical sections may be used or even be advantageous, for example, to prevent rotational movement or to ensure a rotationally fixed arrangement of the first control piston and / or the second control piston relative to the housing and / or to each other. How this is achieved is essentially arbitrary. For example, triangular or rectangular cross-sections or a projection / protruding rail that slides along a guide groove are conceivable.

[0016] The cross-section (e.g., the radius) of the recess can be approximately the same along its axial extent. However, changes in the size of the cross-section (and / or the shape of the cross-section along the axial extent) are also conceivable and can even be advantageous. It is even possible to design the recess such that essentially two recesses are provided for the respective first and second control pistons, so that these are distinguishable from each other but are nevertheless fluidically connected, in particular fluidically connected via a significant cross-section, thus enabling sufficient fluid flow / fluid throughput between the two different recesses.Furthermore, the design should preferably be such that at least a portion of the first control piston can be arranged within at least a portion of the second control piston, at least in certain operating states of the valve device. Typically, the arrangement of the first control piston and / or the second control piston within the recess is such that, at least along certain sections of the control piston / recess, particularly with respect to certain sections of the first control piston, the second control piston, and / or the housing, a substantially fluid-tight sealing contact exists in an axial direction, especially with respect to the fluid to be controlled by the valve device. This sealing functionality can be designed such that the sealing aspect is implemented in such a way that essentially no fluid flow / fluid leakage is possible.It should be noted, however, that a certain amount of fluid leakage is typically unproblematic with respect to the valve device proposed here. On the contrary, such a comparatively small fluid leakage flow can generally be accepted, especially if the mechanical friction between the first control piston, the second control piston, and / or the recess in the housing can be (significantly) reduced by such a design. It should be noted that in typical applications of the valve device proposed here, a certain non-negligible fluid flow through the valve device is maintained in the majority or in (essentially) all operating states of the valve device. Therefore, a small leakage flow is usually not a concern. This, in turn, generally means that, at least for certain operating states (preferably for standard operating states, i.e.,Conditions that occur frequently or even correspond to a / the standard operating mode) where no pronounced minimum fluid pressure occurs at / across the valve device, in particular at at least one of the fluid inlet and / or outlet ports. It should also be noted that it is of course possible to design the sealing part(s) of the valve device and / or additional sections of the valve device in such a way that a specific, predetermined / desired mechanical friction between the respective moving parts (first control piston, second control piston and / or recess of the housing) can be achieved.

[0017] In principle, the movement of the first control piston and / or the second control piston (and possibly other parts of the valve assembly) can be actuated passively (for example, under the influence of the fluid to be controlled by the valve assembly, in particular under the influence of the fluid pressure differential across at least certain parts of the valve assembly, especially across the valve assembly itself, and more specifically between the at least one fluid inlet port and the at least one fluid outlet port of the valve assembly) and / or actively. Actuation can be effected by essentially any type of actuator known in the prior art, including actuators that may be developed in the future. For example, an electric actuator, a fluid pressure-actuated actuator, a mechanically actuated actuator, or the like may be considered.A combination of passively actuated and actively actuated designs is not only possible, but can also be advantageous. For example, the valve assembly can be designed to be passively actuated under normal circumstances. However, for a start sequence, a shutdown sequence, an emergency stop sequence, or similar, control via an externally controlled actuator can be used (where the actuator can, so to speak, amplify, counteract, and / or override the passive operation).

[0018] The phrases "at least one fluid inlet port" and "at least one fluid outlet port" can be interpreted in particular in relation to the housing of the valve device and / or in relation to the fluid connection with an external component. The number of external ports and the number of fluid inlet / outlet ports may vary. In particular, a different number of ports may be advantageous or (essentially) necessary to ensure the desired functionality of the respective valve device. For example, an external fluid inlet line (especially a single one) may be divided into a plurality of fluid inlet ports provided in the housing (housing part) of the valve device.In particular, two, three, four, five, six, or the like fluid inlet ports may be provided in the housing of the valve device, the respective number of fluid inlet ports being connected to a single fluid inlet line (e.g., a pipe or hose) using a fluid distributor or the like. The fluid distributor may be located within the housing (as part of the housing) and / or provided by a separate device, in particular by a separate device attached to the housing of the valve device and / or to the outside of the housing of the valve device. The same may apply additionally or alternatively with regard to the fluid outlet port.

[0019] The valve device is usually designed and configured such that a relative positioning between the first control piston and the housing and / or the second control piston and the housing and / or the first control piston and the second control piston leads to a (partial) opening and / or a (partial) closing of various openings, passages, ports, bores, etc., which are provided in connection with the valve device, in particular in the housing of the valve device and / or in the first control piston and / or in the second control piston.For example, certain positions of the first control piston and / or the second control piston (relative to the housing and / or relative to each other) can cause at least one of the at least one fluid inlet ports to allow and / or restrict fluid flow and / or allow fluid flow between at least one of the at least one fluid inlet ports and at least one of the at least one fluid outlet ports (fluid flow through the valve assembly as a whole) and / or restrict such fluid flow. The same applies analogously to fluid passage ports, which are discussed and proposed below (e.g., inlet and / or outlet ports to / from the first actuating fluid chamber and / or the second actuating fluid chamber, to name just a few examples).

[0020] In particular, it is proposed to design the valve device such that at least part of the first control piston is arranged inside the second control piston, preferably such that a sliding contact is established between the respective surfaces of the first control piston and the respective surfaces of the second control piston. In this way, a particularly compact design of the valve device can be achieved and / or an additional functionality of the valve device can be realized. Similar to the above, the sliding contact between the respective surface of the first control piston and the respective surface of the second control piston can be designed to be substantially fluid-tight (or not fluid-tight, in particular allowing a certain leakage flow) with respect to the fluid to be controlled by the valve device.Furthermore, it should be noted that the arrangement of the valve device can be implemented such that at least part of the first control piston is positioned so that it is located within the second control piston only at certain times and / or in certain operating states of the valve device and / or in certain positions of the various parts of the valve device, in particular in certain positions of the first and second control pistons relative to each other. In other words, it is possible for the first and second control pistons to be, so to speak, out of contact, so that they are, so to speak, offset from each other and / or arranged at a certain distance from each other.In particular, in this case, the first control piston and / or the second control piston may be provided with means to facilitate movement relative to each other in such a way that movement from a separate arrangement of the first control piston and the second control piston to a position in which (a part of the) first control piston is arranged inside (a part of) the second control piston can be facilitated, for example by the use of guiding means such as tapered surfaces on suitable sections at suitable ends of the first control piston and / or the second control piston.

[0021] It is further proposed to design and configure the valve device such that at least the first control piston and / or at least the second control piston, preferably both the first and second control pistons, have an internal recess extending in the axial direction (typically of the respective control piston and / or the valve device). The respective recess(s) may extend only over a specific region of the respective axial direction of the first control piston and / or the second control piston. Preferably, however, the respective recess(s) may extend over the entire length of the respective first control piston and / or second control piston. In other words, the respective first and / or second control piston comprises an (internal) channel that fluidically connects the respective end faces of the respective control pistons.In this way, it is possible to utilize the fluid pressure acting on an end face of the respective control piston to compensate for the respective control piston with respect to the applied fluid pressure (pressure compensation; essentially complete compensation, partial compensation, and / or overcompensation) (and / or possibly also to compensate for and / or influence other devices). As a preferred example, the pressure at the fluid outlet port can be used for pressure compensation (partial compensation or even overcompensation or other influence) of the first control piston and / or the second control piston by transmitting this pressure to the rear faces of the respective control piston(s). Furthermore, (a section of) the inner recess of the second control piston can be used to receive (parts of) the first control piston.It should be noted that the inner recess of the first control piston and / or the second control piston may have an essentially identical inner dimension (diameter) (especially for the first control piston), but may also have sections with different inner dimensions (diameter) (especially for the second control piston).

[0022] In particular, it is proposed to design the valve device such that the first control piston and the second control piston have a first actuating fluid chamber with adjacent pressure surfaces on the first and second control pistons for relative movement between the first and second control pistons. Preferably, the first actuating fluid chamber has at least one combined inlet and outlet opening and / or the first actuating fluid chamber is designed as a dead-end fluid chamber. In other words, the first actuating fluid chamber may only have combined inlet and outlet openings (i.e., there are no separate / different inlet and / or outlet openings). For the sake of completeness, it should be mentioned that minor separate inlet and / or outlet openings (for example, for leakage flows) may nevertheless be present.This design is particularly suitable for converting an absolute pressure of the respective fluid in the first actuating fluid chamber (the fluid pressure at the opening feeding the first actuating fluid chamber) into a relative position of the first control piston with respect to the second control piston (whereby this can also have a (partial) influence on the position of the first control piston and / or the second control piston in the housing recess of the valve device). A combined inlet and outlet opening can be realized by one or more simple fluid channel bores, whereby the respective fluid channel or bores can be used to supply fluid to the first actuating fluid chamber and to discharge fluid from the first actuating fluid chamber (depending on the respective fluid pressures in the different parts of the valve device).In other words, a single combined opening can be provided (which does not preclude the possibility of two, three, or even more, i.e., a plurality of combined inlet and outlet openings (for example, in the form of an arrangement along a circumferential direction of the respective part)). In other words, in this embodiment, the first actuating fluid chamber is typically designed as a kind of pocket-like fluid chamber and / or a dead-end-like fluid chamber, in which only a reciprocating fluid supply / discharge is realized (as opposed to a fluid throughput supply / discharge of fluid via different channels / openings).

[0023] It is further proposed to design the valve device such that a second actuating fluid chamber has adjacent pressure surfaces on the first control piston and on the housing for relative movement between the first control piston and the housing. Preferably, the second actuating fluid chamber has at least one inlet opening and at least one outlet opening, wherein the at least one inlet opening and the at least one outlet opening preferably have different overall cross-sectional areas.In this way, it is easily possible to achieve a specific, desired switching behavior of the valve assembly depending on the fluid to be controlled, in particular depending on the fluid flow at the at least one fluid inlet port and / or at the at least one fluid outlet port, and especially depending on the pressure difference between the at least one fluid inlet port and the at least one fluid outlet port of the valve assembly (i.e., pressure drop across the valve assembly). In other words, this design is particularly well suited to converting a fluid flow into a fluid pressure and thus, in particular, into a specific position of the first control piston and / or the second control piston relative to the housing.In particular, these fluid parameters can be used to effect a specific positioning of the first control piston and / or the second control piston of the valve device, not only with respect to the recess in the housing of the valve device, but especially with respect to a relative positioning between the first control piston and the second control piston (the latter usually in combination with the first actuating fluid chamber and the (one or more) movement limiting means). Specifically, the different dimensions of the overall cross-section of the at least one inlet port (or fluid inlet port) and the at least one fluid outlet port can be used to convert a fluid flow into a pressure / pressure difference between the inlet port and the outlet port of the second actuating fluid chamber.It should be noted that the number of inlet port(s) and the number of outlet port(s) can be the same or different. Furthermore, the different total cross-sectional area of ​​the inlet port(s) and the outlet port(s) can be achieved by a different number of ports and / or by a different size (e.g., bore diameter) of the respective port(s). In particular, the inlet port(s) typically have a larger (total) flow cross-sectional area than the (total) flow cross-section of the outlet port(s). In this context, it should be mentioned (although the following may also apply to other ports / bores / connections and the like) that the terms "inlet" and "outlet" refer to a / the standard operating condition when the valve device proposed here is used as intended (for example, in a hydraulic circuit).

[0024] Furthermore, it is proposed to design the valve device such that at least one movement limiting device is provided to restrict the relative movement between the housing and the first control piston and / or between the first and second control pistons and / or between the second control piston and the housing. This can be achieved by simple (contacting) side walls / stop surfaces of the recess in the valve device housing, end walls of the first control piston, and / or end walls of the second control piston. Alternatively, special contact flanges / stop flanges, protruding pins, or similar devices can be used. This also improves / optimizes the fluid control behavior of the valve device.

[0025] It is further proposed that the valve device be designed such that at least one mechanical preloading device is provided, in particular a mechanical spring. Preferably, the mechanical preloading device acts (directly) between the housing and the first control piston (additionally or alternatively, it can also act between the housing and the second control piston and / or the first control piston and the second control piston; in each case directly or indirectly). In this way, a particularly advantageous relative positioning between the first control piston and / or the second control piston and / or the housing can be achieved (also depending on the parameters of the acting fluid). This results in a (partial) open position and / or a (partial) closed position of the various fluid passage openings, orifices, bores, channels, and the like.In this way, the fluid control behavior of the valve device can be further improved. In particular, the valve device will not guarantee / generate a specific minimum pressure (especially with a specific higher minimum value) in any of its standard operating conditions. Rather, in a standard operating condition (e.g., driving a fluid motor with pressurized fluid in a closed hydraulic circuit pressurized by a fluid pump), the lowest possible pressure is preferred (although a certain pressure can never be completely avoided in reality). For this purpose, the preloading devices are generally designed and configured to apply only a small preload force, which can be easily overcome even at comparatively low pressure values.

[0026] Furthermore, it is proposed to design the valve device such that at least one fluid purge path is provided. Preferably, the at least one fluid purge path establishes a fluid connection with the at least one fluid inlet port and the at least one fluid outlet port of the valve device. The at least one fluid purge path can be influenced by a movement of the first control piston and / or the second control piston (relative to the housing and / or relative to each other), in particular by being (partially) opened and / or (partially) closed. With this design, a corresponding pressure differential between the at least one fluid inlet port and the at least one fluid outlet port of the valve device can be easily set by the relative position of the various parts of the valve device. This is particularly advantageous when realizing a comparatively high pressure differential between the connection ports (e.g., 30 bar or similar).) a (hydraulic / wear-free) braking device for a free-running hydraulic motor, which operates as a hydraulic pump under certain operating conditions and must be braked, can be easily implemented.

[0027] It is further proposed to design the valve device such that at least one fluid flow limiting path is provided, which includes at least one fluid flow limiting means. The fluid flow limiting path is preferably arranged between the at least one fluid inlet opening and the at least one fluid outlet opening of the valve device. Even more preferably, the fluid flow limiting path is arranged between the at least one outlet opening of the second actuating fluid chamber and the fluid outlet opening of the valve device. With such a device, the functionality of providing a fluid pressure differential in certain operating states of the valve device, as described above, can be implemented in a particularly advantageous manner.In particular, the fluid flow limitation path can be defined by a section of an inner axial recess of the first and / or the second control piston (usually the second control piston). Specifically, this particular section of the inner axial recess of the respective control piston can have a cross-section that is small compared to at least one other section, preferably the other sections of the respective control piston.

[0028] Furthermore, it is proposed that the valve device be designed and configured such that it can be operated in at least one flushing position with a first total opening size between the inlet and outlet ports of the valve device, and in a fluid flow restriction position with a second total opening size between the at least one fluid inlet port and the at least one fluid outlet port of the valve device. Providing these at least two positions allows for a particularly easy-to-use valve device. In particular, in the flushing position of the valve device, a drive operation in which a fluid pump drives a fluid motor can be implemented without significant energy losses caused by the valve device.To achieve this, in particular, no significant fluid pressure (minimum fluid pressure) should be present at at least one fluid inlet port of the valve device. Furthermore, the flow restriction position allows for a (rapid) braking mode for a hydraulic motor that can operate as a hydraulic pump in a freewheeling mode. It goes without saying that this type of fluid braking mode typically occurs only occasionally and / or for relatively short periods in standard applications. Generally, the total opening size between the inlet and outlet ports of the valve device in the purge position is significantly larger than the total opening size in the flow restriction position. In particular, no external control means are usually required to achieve this advantageous behavior.

[0029] In particular, it is proposed that the valve device be designed and configured to have a plug-like shape. This allows the valve device to be easily inserted into a corresponding receiving bore. This facilitates quick installation and replacement of the respective valve device. A screw connection can be used as a fastening technique.

[0030] Furthermore, a fluid switching arrangement, in particular a hydraulic switching arrangement, is proposed which can be used to control a fluid motor, wherein the fluid motor can be operated as a fluid pump in a fluid braking mode. The fluid switching arrangement can include a valve device according to the present disclosure. In particular, the fluid switching arrangement can be used to implement a fluid braking device, in particular a fluid rapid braking device, and further, in particular, a fluid emergency braking device, for the fluid motor. As already mentioned (and will be mentioned again below), such a switching arrangement is desirable or even necessary for a variety of different applications. In particular, a comparatively simple design can be implemented. In particular, the functionality of the fluid switching arrangement as proposed here can be implemented without external control.This not only simplifies the design of the respective hydraulic valves, but also eliminates or simplifies the need for control devices to generate control signals for an actuator, or similar improvements.

[0031] Furthermore, a hydraulic arrangement is proposed comprising a valve device according to the present disclosure and / or a fluid switching arrangement according to the present disclosure. The hydraulic arrangement may further comprise a fluid motor for driving a working machine, in particular for driving a working machine with externally accessible moving parts and / or for driving a potentially hazardous working machine, most preferably for driving a mowing device, a cutting device, a rotary mower, or the intake drive of a forage harvester. This proposal may meet safety requirements and / or legal requirements, possibly in a simpler and more cost-effective manner and / or even with a lower potential failure rate and / or in such a way that the resulting machine requires less (preventive) maintenance or the like.

[0032] Furthermore, the use of a valve device according to the present disclosure and / or the use of a fluid switching arrangement according to the present disclosure and / or the use of a hydraulic arrangement according to the present disclosure is proposed, wherein the valve device is used to support or implement a fluid braking mode, in particular a rapid fluid emergency braking mode, and further, in particular, a fluid emergency braking mode. In this proposed use, the aforementioned components and arrangements can particularly well realize their intrinsic properties and advantages. In particular, it is also possible to modify the respective parts, methods, and arrangements according to the present disclosure, at least analogously. In this way, corresponding functionalities and advantages can be realized, at least analogously.

[0033] Further advantages, features and functions of the invention will become apparent from the following detailed description of the invention in conjunction with the associated drawings, the drawings showing: Fig. 1: a schematic cross-section of a possible embodiment of a valve device according to the present disclosure in a rest position; Fig. 2: a schematic cross-section of a possible embodiment of a valve device according to Fig. 1 in a flushing position with low fluid pressure at the fluid inlet opening; Fig. 3: A schematic cross-section of a possible embodiment of a valve device according to the Fig. 1 and Fig. 2 in a first transition position with increasing pressure at the fluid inlet opening; Fig. 4: A schematic cross-section of a possible embodiment of a valve device according to the Fig. 1 to 3 in a second transition position with further increasing pressure at the fluid inlet opening; Fig. 5: A schematic cross-section of a possible embodiment of a valve device according to the Fig. 1 to 4 in a hydraulic brake position; Fig. 6: A schematic circuit diagram of a simplified hydraulic circuit to illustrate the use of a valve device according to the present disclosure, in particular a valve device according to the Fig. 1 to 5.

[0034] Fig. Figure 1 shows a possible embodiment of a valve device 1 according to the present disclosure in a schematic cross-sectional view in an idle position of the valve device 1. This is the position in which the valve device 1 is located when there is no pressure at any of the connection openings 12, 13, 14, 15 of the valve device 1.

[0035] The basic structure of the valve device 1 comprises a housing 2, which in this case has two parts 3, 4 connected to each other by a threaded connection 5. This design facilitates the assembly of the valve device 1 by allowing the various parts 7, 8, 9, which are contained in the inner recess 6 of the housing 2, to be easily inserted before the two parts 3, 4 of the housing 2 are connected to each other by means of the threaded connection 5.

[0036] In the inner recess 6 of the housing 2, a first, inner control piston 7 and a second, outer control piston 8 are arranged. Furthermore, a helical spring 9 is provided to apply a mechanical preload, the mechanical preload being exerted directly on the first control piston 7 and consequently indirectly on the second control piston 8. Both the first and the second control pistons 7, 8 can be moved in an axial direction 10 (as indicated by a double arrow 10 pointing inwards). Fig. (1 indicated) in relation to the longitudinal extent of the housing 2 of the valve device 1, the first, inner control piston 7 can also be moved in relation to the second, outer control piston 8 (relative movement).

[0037] In the present case, the valve device 1 is designed such that the first part 3 and the second part 4 of the housing 2 are fluid-tightly connected to each other.

[0038] Thus, the connection between the first part 3 and the second part 4 of the housing 2 is effectively realized in such a way that no fluid (in particular, no leakage fluid) leaves the housing 2 through the threaded connection 5. Furthermore, the valve device 1 is designed as a plug-like device that is to be inserted into a corresponding flange-like receiving element, which is obvious to a person skilled in the art. To achieve a fluid-tight connection, such that no fluid can escape through the connection between the housing 2 of the valve device 1 and the corresponding flange-like receiving element, an O-ring seal 11 is currently provided.

[0039] The valve device 1 according to the present embodiment has a total of three fluid inlet openings 12, 13, 14 and one (currently single) fluid outlet opening 15. The first, second, and third fluid inlet openings 12, 13, 14 are fluidically connected to each other via a fluid distributor (not shown) and fluidically to a fluid inlet line (in the Fig. 1 to 5 not shown; 32a in Fig. 6) connected. The fluid inlet line 32a / the inlet distributor can be designed in combination with the (also not shown) flange-like receiving part into which the valve device 1 is to be installed.

[0040] For the sake of completeness, it should be noted that the various parts of the valve assembly 1 are essentially rotationally symmetrical about the axial direction 10. Certain deviations from rotational symmetry are evident, for example, due to the threads of the threaded connection 5, the coils of the mechanical spring 9, and the arrangement of the fluid inlet openings 12, 13, 14 (and correspondingly further bores and fluid openings, which will be explained below). In particular, the fluid inlet openings 12, 13, 14 are provided in the form of a plurality of bores arranged along a circumferential direction in the second part 4 of the housing 2 of the valve assembly 1.

[0041] The opposing surfaces of the sliding contact area between the first control piston 7, the second control piston 8, and the inner recess 6 of the housing 2 of the valve device 1 are designed such that essentially no mechanical friction occurs, while the sealing surfaces are essentially fluid-tight except for a certain fluid leakage flow. It should be noted that the fluid leakage flow through the sealing interfaces between the corresponding surfaces of the first control piston 7, the second control piston 8, and the recess 6 of the housing 2 is generally negligible (or at least non-critical), since the valve device 1 is designed to allow a certain fluid flow between the fluid inlet ports 12, 13, 14, and the fluid outlet port 15 in any case.In other words, only the amount of permissible fluid flow is varied between the different operating positions of the valve device 1 (whereby a certain fluid flow is always permitted).

[0042] Furthermore, it is for the expert (especially when considering the other operating positions as described in the Fig. (As shown in Figures 2 to 5 and explained in more detail below), it is evident that, depending on the relative position of the first control piston 7, the second control piston 8, and the housing, two different fluid passage openings are (partially) open or (partially) closed. This will become clearer in the following.

[0043] In Fig. Figure 1 shows the valve assembly in a rest position, the standby position. Now, in the very first phase of switching to a flushing operating position (switching from...), the valve assembly is being shown in its rest position, the standby position. Fig. 1 on Fig. 2) Fluid is supplied to the fluid inlet line 32a and thus (at essentially the same pressure level) to the three fluid inlet openings 12, 13, 14. This is indicated by corresponding arrows symbolizing the fluid flow of the fluid supplied via the inlet line 32a.

[0044] As shown in the schematic cross-section of valve device 1 in Fig. As can be seen in Figure 1, the first, inner control piston 7 is (partially) arranged within the second (outer) control piston 8. Considering the essentially rotationally symmetrical design of the valve device 1 shown here, the first inner control piston 7 forms the radially innermost part, followed by the second control piston 8 and the housing 2 (here, the second part 4 of the housing 2) in the radial direction outwards. For the sake of completeness, it should be mentioned that in the embodiment shown here, the first control piston 7 forms an inner, centrally located bore 16 through which fluid can flow (which extends over the entire axial extent of the first control piston 7 and thus connects both end faces of the first control piston 7). The second control piston 8 also has an inner, centrally located recess that extends over the entire axial extent of the second control piston 8.It should be noted that the centrally located inner recess of the second control piston 8 has a section with a significantly varying cross-section / inner diameter. The left sections (as shown in the . Fig. 1-5 shown) have a large inner diameter, while the inner diameter of the right section (which forms the throttle line 26; see below) is significantly smaller.

[0045] When fluid is supplied to the inlet openings 12, 13, 14 of the valve device 1 (via the fluid line 32a), a portion of the inflowing fluid passes through the first fluid inlet opening 12, the fluid line gap 22, and a suitably arranged bore 17 into a first actuating fluid chamber 18. Pressure in the first actuating fluid chamber 18 generates a static pressure force on the first and second control pistons 7, 8 via corresponding pressure surfaces. The resulting static pressure force counteracts the preload force of the mechanical spring 9 and causes the first control piston 7 and the second control piston 8 to move relative to each other in a separating direction (opening the first variable throttle opening 19 between the first control piston 7 and the second control piston 8). As shown in the present case. Fig. As shown in Figure 1, the first control piston 7 is pushed to the left, while the second control piston 8 is in Fig. 1 is pushed to the right. It should be noted that the mechanical spring 9 tends to push the control piston 7 and the control piston 8 together, thus closing a variable throttle opening 19 between the first and second control pistons 7, 8. This closing mechanical contact also limits the relative mechanical movement between the first control piston 7 and the second control piston 8. The preload force exerted by the mechanical spring 9 is chosen to be comparatively low, so that even a relatively small pressure at the inlet openings 12, 13, 14 can overcome this force.

[0046] A further portion of the inflowing fluid enters the second actuating fluid chamber 20 through the second fluid inlet opening 13. This leads to a corresponding pressure build-up in the second actuating fluid chamber 20 and thus to a static pressure acting on the various boundary surfaces of the second actuating fluid chamber 20. This causes a movement of the second control piston 8 to the left relative to the housing 2 of the valve device 1. It should be noted that, due to the mechanical contact between the first and second control pistons 7, 8, which defines the variable throttle opening 19, a movement of the second control piston 8 to the left also causes a movement of the first control piston 7 to the left.

[0047] Therefore, the combined mechanical forces generated by the first and second actuating fluid chambers 18, 20 cause a movement of the second control piston 8 to the left and a so to speak accelerated movement of the first, inner control piston 7 to the left.

[0048] At this point, the remaining portion of the supplied fluid entering (or attempting to enter) the third fluid inlet opening 14 does not cause any axial movement of the various parts of the valve assembly 1. Furthermore, since the variable throttle opening 21 between the second control piston 8 and the second part 4 of the housing 2 is closed, no fluid initially flows through the fluid inlet opening 14.

[0049] This initial supply of fluid at the inlet openings 12, 13, 14 of the valve device 1 corresponds to a start-up process of a hydraulic circuit 27 (see Fig. ), in which a fluid pump 28 begins to pump fluid to supply a hydraulic motor 29 for driving a tool 31 (or more generally: a mechanically operated device 31). The supplied hydraulic fluid flows through the hydraulic motor 29, where the pressure energy of the pressurized fluid is converted into mechanical energy (rotational energy), and the fluid leaving the hydraulic motor 29 is returned to the fluid reservoir 33.

[0050] In Fig. Figure 2 shows a further schematic cross-section illustrating a flushing operating state of the valve device 1. This operating state (flushing operating state) corresponds to a situation in which the drive of the hydraulic motor 29 of the in Fig. Circuit 27 as shown in section 6 is fully manufactured.

[0051] As from Fig. As can be seen in Figure 2, the pressure of the fluid acting on the inlet openings 12, 13, 14 of the valve device 1 continues to enter the first actuating fluid chamber 18, specifically via the first fluid inlet opening 12, the sufficiently dimensioned fluid line gap 22, which is provided between the outer surface of the second control piston 8 and the inner surface of the recess 6 of the housing 2 in its respective axial section, and the corresponding bore 17 of the second control piston 8. This pushes the first control piston 7 further to the left (the movement being (partially) counteracted by the force of the mechanical spring 9). Fluid also enters the second actuating fluid chamber 20 through the second fluid inlet opening 13, exerting a leftward force on the second control piston 8. Unlike in Figure 2, the fluid in the second actuating fluid chamber 18 is not affected by this force. Fig. In position 1, the variable throttle opening 21 between the second control piston 8 and the second part 4 of the housing 2 is fully open. Therefore, a considerable fluid flow passes through the third fluid inlet opening 14 and thus between the fluid inlet line 32a and the fluid outlet opening 15 of the valve device 1. Accordingly, the fluid flow resistance of the valve device 1 is comparatively low, which is the desired operating characteristic for a flushing position of the valve device 1 (i.e., a low fluid pressure is present at the inlet openings 12, 13, 14).

[0052] For the sake of completeness, it should be noted that, depending on the exact pressure situation of the valve device 1, the first variable throttle opening 19 between the first control piston 7 and the second control piston 8 may also be open to a certain degree. However, since the fluid outlet opening 23 of the second actuating fluid chamber 20 remains closed, no relevant fluid flow passes through this variable throttle opening 19.

[0053] Now the fluid supply is increased by the hydraulic pump 28 (see Fig. ) stopped and the hydraulic motor 29, which is driven by mechanical inertia, begins to operate as a fluid pump. Therefore, the fluid pressure in the fluid inlet ports 12, 13, 14 of the valve device 1 begins to rise. In particular, in this situation, the fluid flow through the third fluid inlet port 14 and the second variable throttle port 21 to the fluid inlet port 15 is insufficient to prevent a pressure increase at the fluid inlet ports 12, 13, 14.

[0054] As a result, the fluid pressure in the first and second actuating fluid chambers 18, 20 continues to increase. Therefore, the first control piston 7 is pushed further to the left, while a corresponding movement of the second control piston 8 to the left is limited by corresponding stop surfaces 24 between the housing 2 and the second control piston 8 (see Fig. 3) This leads to a relative separation movement of the first control piston 7 and the second control piston 8, so that finally the outlet opening 23 of the second actuating fluid chamber 20 opens.

[0055] Fig. Figure 4 shows the situation in a further developed transition state in which both the movement of the first control piston 7 to the left and the movement of the second control piston 8 to the left is prevented by a mechanical contact of the respective stop surfaces 25 and 24 of the first control piston 7, the second control piston 8 and the housing 2.

[0056] A fluid flow now occurs through the second fluid inlet opening 13, the second actuating fluid chamber 20, and the fluid outlet opening 23 into the interior of the second control piston 8, further through the first variable throttle opening 19 (which has opened) between the first control piston 7 and the second control piston 8, and finally through the throttle line 26, which is connected to the second control piston 8, towards the fluid outlet opening 15. Simultaneously, a fluid flow occurs through the third fluid inlet opening 14 and the second variable throttle opening 21 to the fluid outlet opening 15.

[0057] It should be noted that the inner control piston 7 of the valve device 1 remains in its leftmost position due to the different total flow cross-sections of the second fluid inlet port 13 and the outlet port 23 of the second actuating fluid chamber 20. In this case, the total size of the second fluid inlet port 13 is twice the total cross-section of the outlet ports 23. Therefore, a (possibly somewhat reduced) fluid pressure remains inside the second actuating fluid chamber 20. Furthermore, it should be noted that a static fluid pressure remains in the first actuating fluid chamber 18. Moreover, the pressure in the recess 6 of the housing 2 is lower than the pressure in the second actuating fluid chamber 20 and, in particular, lower than the pressure in the first actuating fluid chamber 18.In this context, it should be noted that the pressure in the recess 6 is transmitted through the central bore 16 (which is located inside the first control piston 7) and thus acts on the respective end faces of the first control piston 7 and the second control piston 8 (and thus rests against the stop surfaces 24 and 25).

[0058] The described combination of maintaining fluid pressure in the first actuating fluid chamber 18 and a relative pressure drop in the second actuating fluid chamber 20 due to the opening of the outlet port 23 leads to a movement of the second control piston 8 to the right, while the first control piston 7 remains in its extreme left position, in which the stop surfaces 25 of the first control piston 7 and the housing 2 remain in contact. This is again due to the fact that the static pressure in the first actuating fluid chamber 18 is higher than the static pressure in the second actuating fluid chamber 20 and, in particular, higher than the static pressure in the recess 6, resulting in a force acting on the second control piston 8, with the force being directed to the right; consequently, the second control piston 8 will move to the right.

[0059] This places the valve device 1 into the Fig. The third fluid inlet opening 14 is brought to the position shown in Figure 5. Here, the third fluid inlet opening 14 is no longer fluidically connected to the fluid outlet opening 15, since the second variable throttle opening 21 between the second control piston 8 and the housing 2 is closed. A reduced fluid flow is (still) possible through the second fluid inlet opening 13 via the second actuating fluid chamber 20, the outlet opening 23, the fully opened variable throttle opening 19, and finally the throttle line 26 of the second control piston 8.

[0060] Due to the reduced fluid flow combined with a still high inlet fluid flow resulting from the pumping action of the fluid motor 29, a high pressure build-up occurs on the inlet side of the valve device 1. This leads to a very effective hydraulic braking of the hydraulic motor. This is, of course, a desired behavior.

[0061] When the hydraulic motor 29 finally comes to a standstill, the fluid pressure at all three fluid inlet openings 12, 13, 14 drops to (essentially) zero, and the valve assembly 1 returns to its rest position, as shown in Fig. 1 shown.

[0062] Fig. Figure 6 shows the schematic diagram of a hydraulic circuit 27 which uses a valve device 1 according to the present disclosure. The schematic diagram of the hydraulic switching arrangement 27 is very simplified and kept very basic in order to highlight the essential points.

[0063] The hydraulic circuit 27 comprises a hydraulic pump 28 and a hydraulic motor 29. The hydraulic pump 28 is driven by a primary drive 30, for example, an internal combustion engine or an electric motor (possibly battery-powered or the like). The hydraulic motor 29 is connected to a mechanically operated device 31, such as a mower or the intake drive of a forage harvester, or the like. The hydraulic components of the hydraulic circuit 27 are connected to each other in the usual way by hydraulic lines 32 (32a-32f), such as pipes or hoses. Furthermore, a hydraulic fluid reservoir 33 is provided for storing and buffering hydraulic fluid.

[0064] In normal operation of hydraulic circuit 27, the primary drive powers the hydraulic pump 28. The hydraulic fluid is drawn from the hydraulic fluid reservoir 33 via hydraulic circuit 32b, pressurized, and conveyed to the hydraulic motor 29 via hydraulic line 32a. The hydraulic motor 29 converts the pressure energy of the hydraulic fluid into mechanical energy, which in turn drives the mechanically operated device 31. The fluid, essentially at ambient pressure, is expelled from the hydraulic motor 29 via hydraulic line 32c, valve assembly 1, and hydraulic line 32d into the fluid reservoir 33. In this operating mode (flushing operation), the valve assembly 1 should offer essentially no flow resistance (although a certain pressure drop across the valve assembly 1 is, of course, unavoidable). In other words, the pressure differential between hydraulic lines 32c and 32d should be as small as possible.In this way, the fluid pressure supplied by the hydraulic motor 29 does not have to work against an increased fluid pressure, which in turn saves energy. This flushing position of the valve device 1 is in . Fig. 3 shown.

[0065] If the hydraulic motor 29 (and the associated mechanically driven device 31) is to be slowed down or stopped, the hydraulic pump 28 is stopped (or, in the case of a variable displacement hydraulic pump 28, the pumping rate is reduced accordingly, for example, to (essentially) zero). The mechanical inertia of the mechanically driven device 31 then begins to drive the hydraulic motor 29, which in turn begins to operate as a fluid pump in this state. To prevent cavitation, a check valve 34 is provided, allowing hydraulic fluid to be drawn from the hydraulic fluid reservoir 33 via the hydraulic lines 32e and 32f.

[0066] To decelerate the hydraulic motor 29 and the mechanically actuated device 31 as quickly as possible, a high fluid pressure should be present at the output port of the hydraulic motor 29 (i.e., in the hydraulic line 32c leading to the valve device 1). Therefore, the valve device 1 should switch to a position / operating mode that results in a higher pressure drop across the valve device 1. This is the position / operating mode described in Figure 1. Fig. The operating position of the valve device 1 is shown. To name just a few parameters: The pressure in the fluid line 32c upstream of the valve device 1 is usually between 20 and 50 bar, typically around 30 bar, while the pressure downstream of the valve device 1 in the hydraulic line 32d is approximately equal to the ambient pressure.

[0067] It should be noted that the previously described advantageous switching behavior of the valve device 1 can be achieved without any external actuation of the valve device 1. This makes the entire arrangement of the hydraulic circuit 27 structurally simpler and more cost-effective. Furthermore, some potential causes of failure are eliminated from the arrangement (e.g., a defect in an actuator for a valve device), thereby increasing the reliability of the hydraulic circuit 27.

[0068] It should be noted that a single or a multitude of features of one, several or all of the detailed embodiments currently disclosed may be used in combination with the general description of the present disclosure.

Claims

[1] Valve device (1), in particular a fluid pressure differential dependent flushing valve device (1), comprising a first control piston (7), a second control piston (8), and a housing (2) with at least one fluid inlet opening (12, 13, 14), at least one fluid outlet opening (15) and a recess (6) for receiving the first control piston (7) and the second control piston (8), wherein the valve device (1) is designed and configured such that the first control piston (7) and / or the second control piston (8) are displaceable relative to the housing (2), and wherein the first control piston (7) and the second control piston (8) are displaceable relative to each other. [2] Valve device (1) according to claim 1, characterized by, that at least a part of the first control piston (7) is arranged such that it is located inside the second control piston (8), preferably such that there is a sliding contact between the respective surfaces of the first control piston (7) and the respective surfaces of the second control piston (8). [3] Valve device (1) according to claim 1 or 2, characterized by , that the first control piston (7) and the second control piston (8) have a first actuating fluid chamber (18) with adjacent pressure surfaces on the first control piston (7) and on the second control piston for a relative movement between the first control piston and the second control piston (18), wherein the first actuating fluid chamber (18) preferably has at least one combined inlet and outlet opening (13) and / or wherein the first actuating fluid chamber is designed as a dead-end fluid chamber (18). [4] Valve device (1) according to one of the preceding claims, characterized bya second actuating fluid chamber (20) with adjacent pressure surfaces on the first control piston (7) and on the housing (2) for a relative movement between the first control piston (7) and the housing (2), wherein the second actuating fluid chamber (20) preferably has at least one inlet opening (14) and at least one outlet opening (23), wherein the at least one inlet opening (14) and the at least one outlet opening (23) more preferably have different overall cross-sections. [5] Valve device (1) according to one of the preceding claims, characterized by at least one movement limiting means (19, 21, 24, 25) for limiting the relative movement between the housing (2) and the first control piston (7) and / or between the first control piston (7) and the second control piston (8) and / or between the second control piston (8) and the housing (2). [6] Valve device (1) according to one of the preceding claims, characterized byat least one mechanical preloading means (9), in particular by means of a mechanical spring (9), wherein the mechanical preloading means (9) preferably acts between the housing (2) and the first control piston (7). [7] Valve device (1) according to one of the preceding claims, characterized by at least one fluid flushing path, which preferably establishes a fluid connection between the at least one fluid inlet opening (12, 13, 14) and the at least one fluid outlet opening (15) of the valve device (1), wherein the at least one fluid flushing path can be influenced by a movement of the first control piston (7) and / or the second control piston (8), in particular being able to be opened and closed. [8] Valve device (1) according to one of the preceding claims, characterized byat least one fluid flow limiting path with at least one fluid flow limiting means (19, 21, 26) which is preferably arranged between the at least one fluid inlet opening (12, 13, 14) and the at least one fluid outlet opening (15) of the valve device (1), particularly preferably between the at least one outlet opening (23) of the second actuating fluid chamber (20) and the fluid outlet opening (15) of the valve device (1). [9] Valve device (1) according to one of the preceding claims, characterized by, that it is designed and configured in such a way that it can be operated at least in a flushing position with a first total opening size between the inlet opening (12, 13, 14) and the outlet opening (15) of the valve device (1), and in a fluid flow constriction position with a second total opening size between the at least one fluid inlet opening (12, 13, 14) and the at least one fluid outlet opening (15) of the valve device (1). [10] Fluid switching arrangement (27), in particular hydraulic switching arrangement (27), for controlling a fluid motor (29) which can be operated as a fluid pump in a fluid braking mode of the fluid motor (29), comprising a valve device (1) according to one of the preceding claims, in particular for realizing a fluid braking device, in particular a fluid rapid braking device, further in particular a fluid emergency braking device, for the fluid motor (29). [11] Hydraulic arrangement (27) comprising a valve device (1) according to one of claims 1 to 9 and / or a fluid switching arrangement (27) according to claim 10, further comprising a fluid motor (29) for driving a working machine (31), in particular for driving a working machine with externally accessible moving parts and / or for driving a potentially dangerous working machine, preferably for driving a mowing device, a cutting device, a rotary mowing device or a feed drive of a forage harvester. [12] Use of a valve device (1) according to any one of claims 1 to 9 and / or a fluid switching arrangement according to claim 10 and / or a hydraulic arrangement (27) according to claim 11, wherein the valve device (1) is used to support or implement a fluid braking mode, in particular a fluid rapid braking mode, and further in particular a fluid emergency braking mode.

Images