DE102019117233A1 - Pressure return piston with annular shoulder - Google Patents

Abstract

The invention relates to an electromagnetically operated piston slide valve (1), comprising: a valve housing (9) with a first fluid connection (11) and a second fluid connection (12) and with a fluid channel (13) connecting the two fluid connections, and a piston slide arrangement with a piston slide (14) which is axially displaceable to change a free cross section of the fluid channel (13), preferably on a guide pin (15) with radial passage openings (17) that can be closed by the piston slide, characterized by at least one axially displaceable in a pressure return channel (25) guided pressure return piston (21) with opposing first and second axial ends (24a, 24b), with a first piston section (22a) with a first cross-sectional area, a second piston section (22b) with a second cross-sectional area, and an intermediate transition section (23), - The first cross-sectional area being smaller than the second transverse sectional surface is formed, and- wherein the first axial end (24a) of the pressure return piston is provided to urge the piston slide (14) in the direction of an open position.

Description

FIELD OF THE INVENTION

The present invention relates to a piston valve, in particular a control or proportional throttle valve, a piston valve for the piston valve and a shock absorber for a vehicle with such a piston valve.

BACKGROUND OF THE INVENTION

Adjustable or controllable valves or valves with adjustable flow resistance are used in hydraulic shock absorbers of vehicles as damper valves in order to control or regulate the flow of hydraulic fluid between the damper chambers of a shock absorber and thus its damping characteristics (for example "hard" or "soft") ). Electromagnetically actuated piston slide valves are often used as valves, which are designed as control valves and, if necessary, as proportional valves or throttles. In piston slide valves of this type, an axially displaceable piston slide moves on a guide pin with radial fluid passage openings, which enables the free flow cross-section to be changed in a targeted manner regardless of auxiliary variables. A proportional characteristic can be achieved by suitable coordination and dimensioning of the components of the electromagnetic drive and / or the piston slide arrangement, whereby, for example, the stroke of the magnet armature and / or the free cross section of the fluid passage openings changes at least approximately proportionally to the drive current or to the displacement of the piston slide.

On the other hand, external impacts on the shock absorber cause a fluid displacement from one damper chamber via the damper valve into the other damper chamber and corresponding pressure differences or pressure surges at the valve or at its fluid connections. It is often undesirable here for the flow resistance and thus pressure loss or pressure drop at the valve to increase sharply, in particular non-linearly, with increasing fluid flow. With flow fluctuations this can lead to a strong build-up of pressure, which is disruptive in many applications. Instead, what is desired is a less sharply increasing, for example linear, increase in the pressure drop with increasing flow or even a degressive behavior.

It is known to provide a so-called pressure sensing pin or pressure return piston, which is axially displaceable and converts such pressure differences into a mechanical actuating force that, together with the electromagnetic and / or elastic actuating forces, determines the position of the piston slide and pushes it in the direction of the open position around the free To increase the flow cross-section and thus to let the pressure drop at the valve rise less sharply with increasing fluid flow or high pressure difference at the fluid connections. Such a pressure return piston thus influences the characteristic curve of the damper valve, which leads to a softer damper characteristic as a result of a pressure surge or to a softer dynamic damper behavior (blow-off behavior). These valves have a piston slide with a cup-shaped, cylindrical or ring-like section with a hydraulic control edge for regulating the flow cross-section of radially extending fluid passage openings. The pressure return pistons of such valves, as for example in DE 10 2007 058 620 B3 and DE 10 2008 035 899 A1 are disclosed, but only act in one flow direction, for example in the event of pressure surges at the axial pressure connection, so that these valves can only be operated in one flow direction. It is accordingly necessary to provide two separate damper valves for the shock absorber, ie one valve per direction of flow (rebound and compression stage), and the corresponding hydraulic lines, including check valves, flow crossings and the like. Because of the space required for such an arrangement, it is then usually attached to the outside of a shock absorber, since the space inside the shock absorber is limited. However, the valves attached to the outside of the shock absorber pose a risk of collision with surrounding components of the vehicle.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a simple and compact piston slide valve which provides flexible pressure return with a compact design, as well as a suitable piston slide and a corresponding shock absorber.

The problem is solved by the independent claims. Advantageous refinements and developments are given in the dependent claims.

The present invention creates a piston slide valve with a valve housing with a first fluid connection and a second fluid connection and at least one fluid channel connecting the two fluid connections.

The piston slide valve has a piston slide arrangement which is arranged in the valve housing and has a piston slide, which is usually movable or displaceable for changing a free cross section of the fluid channel linear and axial or along a longitudinal or central axis of the valve. The piston valve has a, for example, cup-shaped, cylindrical or ring-like piston valve section with a conically tapering control edge, which is slidably guided on a corresponding guide pin, the guide pin being part of the valve housing or being firmly connected to it. In the simplest case, the ring-like piston slide section and the corresponding guide pin have a circular cross-section transverse to the longitudinal axis of the valve. However, other cross-sections are also conceivable, for example a triangular, square, hexagonal or hexagonal or octagonal cross-section. The guide pin has, for example, radial or perpendicular to the direction of movement of the piston slide fluid passage openings that form a section of the fluid channel and can be opened and closed with the aid of the piston slide in a known manner to allow the free flow cross-section of the fluid channel and thus a hydraulic fluid flow or to regulate the flow resistance between the first fluid connection and the second fluid connection.

The piston slide valve is usually an active, electromagnetically operated piston slide valve, with an electromagnetic linear drive for the piston slide, in which the electromagnetic linear drive or the piston slide works in a manner known per se against a mechanical spring element. For this purpose, the piston slide valve usually comprises an electrically energized coil for generating an electromagnetic field with which a magnet armature connected to the piston slide can be moved in order to provide the desired linear drive. However, instead of the electromagnetic linear drive, it is also conceivable to provide only one pretensioning spring that can be adjusted from the outside, for example, or some other drive for the piston slide.

According to the invention, at least one pressure return pin or pressure return piston is provided in the piston slide valve, which is displaceably guided in a corresponding pressure return channel. The pressure return piston and pressure return channel have a common longitudinal axis, this usually running parallel to the longitudinal axis of the valve, along which the piston slide is displaceable.

The pressure return piston has first and second axial piston sections each with first and second cross-sectional areas transverse to the longitudinal axis, the surface areas of which are of different sizes. In the following, by definition, the area of the first cross-sectional area is smaller than the area of the second cross-sectional area. In the simplest case, the cross-sectional areas of both piston sections are circular so that cylindrical piston sections result as the respective outer shape. However, other cross-sections are also conceivable for one or both piston sections, for example a triangular, square, hexagonal or hexagonal or octagonal cross-section. It is preferred that the centroids of the cross-sectional areas of both piston sections are arranged axially on a common axis that forms the longitudinal or central axis of the pressure return piston, in order to prevent the pressure return piston from tilting in the pressure return channel. In the case of cylindrical piston sections, the piston sections are therefore concentric to one another. The axial lengths of the piston sections are preferably in the range between 1 and 20 mm and are, for example, 1, 2, 3, 5, 7, 10, 15 or 20 mm, whereby each of the values mentioned can also be an upper or lower limit of the mentioned range . Both piston sections are preferably of the same length. Furthermore, the piston sections preferably each have diameters in the range 1 and 10 mm, which differ by a diameter difference which is in the range between 0.01 and 5 mm and, for example, 0.01, 0.02, 0.05, 0.1 , 0.2, 0.3, 0.5, 0.7, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0 or 5.0 mm, any of values mentioned can also be an upper or lower limit of the range mentioned. Correspondingly, for example, the diameter of the first cross-sectional area is 1, 2, 3, 5, 7 or 10 mm, wherein each of the stated values can also be an upper or lower limit of the aforementioned range.

Axially between the two piston sections of the pressure return piston is a transition section, designed in the simplest case as an annular shoulder, which forms the transition between the first and second cross-sectional areas or between the first and second piston sections or in which the cross-section of the pressure return piston is from the first to the second cross-sectional area changes, preferably as a step or gradually and / or monotonously. In the first case, the transition section has an extension of zero in the axial direction and is designed, for example, as a flat annular shoulder or ring surface, the shoulder width of which is, for example, equal to half the diameter difference of the piston sections. In the latter case, the transition section is axially extended and has, for example, an axial length in the range between 0.1 and 10 mm, which is 0.1, 0.2, 0.5, 0.7, 1, 1.5, 2 , 3, 5, 7 or 10 mm, each of the values mentioned can also be an upper or lower limit of the stated range. The pressure return piston preferably has an overall length in the range from 2 to 40 mm, which is for example 2, 3, 5, 7, 10, 15, 20, 30 or 40 mm, each of the values mentioned can also be an upper or lower limit of the range mentioned.

Along the piston sections of the pressure return piston, the cross-sectional area is constant or uniform and the piston sections and thus the pressure return piston are guided in respective corresponding channel sections of the pressure return channel, which each have a cross-sectional area complementary or corresponding to the cross-sectional area or outer shape of the respective piston section as an inner shape as well as a in the simplest case have a concentric arrangement which corresponds to the relative arrangement of the piston sections, and are usually each designed as optionally elongated through holes. Correspondingly, the cross-sectional areas of both channel sections are circular in the simplest case so that cylindrical channel sections result. Corresponding to the respective piston sections of the pressure return piston, the cross-sectional area of one or both channel sections can also be, for example, triangular, square, hexagonal or hexagonal or octagonal. Axially between the channel sections, the pressure return channel has a channel transition section corresponding to the transition section of the pressure return piston, within which the transition section of the pressure return piston moves axially and which can preferably be subjected to hydraulic pressure. The axial length of the duct transition section is usually equal to or greater than the desired travel path of the pressure return piston. Accordingly, the axial length of the duct transition section of the pressure return duct is preferably in the range between 1 and 10 mm and is, for example, 1, 2, 3, 5, 7 or 10 mm, each of the values mentioned can also be an upper or lower limit of the stated range. The pressure return duct can be formed in the valve housing or in a separate guide body described below.

The pressure return piston is preferably formed in one piece or from a single material and is created, for example, in a common or single production step. Correspondingly, a one-piece component has the same material and a uniform material structure throughout. The pressure return piston is particularly preferably a component that does not come from a tool. The pressure return piston can also be designed as a pin ground with high precision. Additional sealing elements in the pressure return channel, such as O-rings or elastomers, are preferably dispensed with, which means that the design of the piston slide valve can be made inexpensive and compact and frictional forces that would reduce the usable pressure force are avoided.

In the simplest case, the first and second piston sections of the pressure return piston extend from the intermediate transition section to a first and second axial end of the pressure return piston, so that the opposite axial ends of the pressure return piston are preferably each designed as flat end faces which are identical to the cross-sectional area of the respective piston section and are aligned perpendicular to the longitudinal axis of the pressure return piston. Correspondingly, the pressure return piston preferably consists exclusively of the two piston sections and the transition section along its longitudinal axis. Likewise, the pressure return channel preferably consists exclusively of the two channel sections and the channel transition section along its longitudinal axis.

The cross-sectional areas of the piston sections or, in the simplest case, the flat end faces at the ends represent the hydraulically effective axial end areas of the pressure return piston, which according to the invention are of different sizes. These thus represent hydraulically unbalanced ends of the pressure return piston, via which an actuating force resulting from hydraulic pressure can be generated in the axial direction on the pressure return piston or can be exerted by the pressure return piston on other components such as the piston slide. The invention allows the hydraulically effective surfaces of the axial ends or the transition section to be freely selected and thus to adjust the strength of the actuating force and thus creates a further degree of freedom for setting the corresponding pressure-actuating force characteristic of the pressure return piston.

According to the invention, the first axial end of the pressure return piston, which is assigned to the first piston section and which in the simplest case is designed as a flat end face, is set up to urge the piston slide in the direction of an open position. In the simplest case, the smaller or first axial end or the first end or end face of the pressure return piston is in (direct, immediate) engagement with the piston valve and / or is designed to be in direct contact with the piston valve. Alternatively, the actuating force generated by the pressure return piston can also be provided to be transmitted indirectly, for example via an intermediate component, to the piston slide, so that it is pushed towards an open position.

The position of the piston slide along its travel path is correspondingly - additional to the forces resulting from the electromagnetic drive or external spring elements - also determined by the force exerted by the pressure return piston. The piston slide valve according to the invention with the pressure return piston described enables flexible pressure return, whereby the pressure return can be adapted to different scenarios of pressure surges or differences at the fluid connections depending on the pressurization of the axial ends and the transition section of the pressure return piston and at the same time enables a compact design . In particular, when the axial ends and the transition section are suitably pressurized with the various hydraulic pressures occurring at the valve, the piston slide valve according to the invention always enables an actuating force to be generated on the piston slide, particularly in the direction of an open position, such that the free cross section of the fluid channel is enlarged.

According to the invention, flow forces on the piston can thus be compensated for in that the piston is pushed in the direction of the open position by means of the pressure return piston. This can also be used as a so-called blow-off behavior of the piston slide valve in a targeted and desired manner. In the event of an increasing increase in the volume flow, for example due to a shock on the shock absorber on which the valve is mounted, the pressure loss at the piston slide valve is thus limited, since the piston slide valve then opens accordingly by means of the pressure return piston. By selecting the cross-sections of the pressure return piston and, if necessary, the number of pressure return pistons, the characteristic curve of the piston slide valve can be influenced in a targeted manner.

Both axial ends of the pressure return piston are preferably hydraulically connected to the second, for example a radial, fluid connection of the valve and the pressure return piston is hydraulically connected at its transition section to the first, for example an axial fluid connection. Correspondingly, if the pressure applied to the second fluid connection is greater than the pressure applied to the first fluid connection (11), the pressure return piston (21a, 21b) is pushed in the direction of its first axial end and thus generates an actuating force on the piston slide in the direction of the open position.

In the simplest case, hydraulically connected means that at points or sections of the piston valve that are hydraulically connected to each other, the same pressure prevails at all times, even during pressure surges, and a dynamic pressure drop does not occur or is at least negligible. Pressure surges occur on different time scales. They can take place quasi-stationary and, for example, be in the seconds range, or highly dynamic and, for example, in the millisecond range when the vehicle is driving through a pothole, for example. In other words, the hydraulically connected sections of the piston slide valve are located in a common pressure space in which no or only a negligible dynamic pressure drop occurs. Pressure surges of up to several hundred bar typically occur at the fluid connections, which typically results in an actuating force of the pressure feedback piston of up to 10 Newtons.

In the usually exactly two channel sections of the pressure return channel, the respective piston sections of the pressure return piston are arranged and preferably guided in a sealing manner, with a clearance fit or a narrow radial gap between the piston sections of the pressure return piston and the channel sections of the pressure return channel being provided for the sliding of the pressure return piston in the pressure return channel . This measure suppresses the leakage flow through the pressure return duct and / or reduces it to a negligible amount. The clearance fit can be designed, for example, as an H7 / h6 or H8 / h9 or H1 1 / h9 clearance fit. Alternatively or additionally, it is advantageous if the pressure return channel - apart from the pressure return piston itself - does not have a (further, separate) sealing element or sealing element, such as an elastomer sealing ring, as this would hinder the desired sliding of the pressure return piston.

According to the definition, the axially displaceable piston valve in its open position is at a maximum distance from a first axial end of the piston valve valve along its travel path and accordingly has a minimum distance from this first axial end of the piston valve valve in its closed position. In a preferred embodiment, the first fluid connection is then arranged at least closer to the first axial end of the piston slide valve than the second fluid connection. The second fluid connection is correspondingly at a greater distance from the first axial end than the first fluid connection. The first fluid connection is particularly preferably arranged at the first axial end or the first fluid connection forms the first axial end of the piston slide valve, the first fluid connection being in particular an axial fluid connection in which the flow direction of the hydraulic fluid is also essentially axial. In this case, the second fluid connection is arranged at a distance from the first axial end and is preferably designed as a radial fluid connection in which the direction of flow runs essentially radially.

In such an arrangement, the pressure return piston according to the invention is used to generate an actuating force in the direction of the open position of the piston slide and thus away from the first, possibly axial, fluid connection when the pressure at the first fluid connection is lower than that at the second, possibly radial, fluid connection, with such pressure conditions often also referred to as fluid reflux. In other words, the invention enables a force deflection with which an actuating force of the pressure return piston can be generated spatially opposite to the flow direction in the valve or in the direction of the fluid connection with the higher pressure and thus pressure return to the piston slide even with fluid backflow.

The interior of the valve housing of the piston slide valve according to the invention, in which the piston slide arrangement is arranged, or the piston slide arrangement arranged in the interior of the valve housing is preferably designed such that in the entire interior of the valve housing or on all sections of the piston slide arrangement either the pressure of the first fluid connection or the pressure of the second fluid connection prevails. In other words, all points of the interior of the valve housing or all sections of the piston slide arrangement are hydraulically connected to either the first or the second fluid connection, so that there are only exactly two pressure levels in the entire interior of the valve housing. The interior of the valve housing is preferably divided into exactly two, usually connected, pressure chambers in which either the pressure of the first or the second fluid connection prevails.

Accordingly, for example, the entire interior of the guide pin and possibly the transition section of the pressure return piston is hydraulically connected to the first fluid connection, while the remaining interior, such as an outer space of the guide pin and the piston slide and an interior of the piston slide, which is located outside the guide pin and not through the Guide pin is filled, and optionally the two axial ends of the pressure return piston, hydraulically connected to the second fluid connection. For this purpose, the entire interior of the valve housing or the piston slide arrangement is provided with sufficiently large fluid passages between the various sections in the interior of the valve housing.

There are therefore exactly two defined pressure levels within the valve housing or on the piston slide assembly, so that in particular the pressure return piston is not subjected to undefined intermediate pressures at, for example, its axial ends and the transition section, but only to the defined pressure levels of the first and second fluid connections. This favors the generation and setting of a defined actuating force of the pressure feedback piston or its pressure-actuating force characteristic.

The pressure return piston is preferably arranged at a radial distance from the (central) longitudinal axis or central or symmetry axis of the piston slide valve, in the simplest case the longitudinal axis of the pressure return piston is parallel to the longitudinal axis of the piston slide valve. The pressure return piston is preferably spaced from the longitudinal axis of the piston slide valve in such a way that the pressure return piston or its longitudinal axis is arranged on a radial outside of the piston slide and guide pin, which simplifies the desired hydraulic connection of the axial ends and the transition section of the pressure return piston. The channel section of the pressure return channel leading the first piston section of the pressure return piston preferably opens directly into the pressure chamber of the second fluid connection.

It is preferably also provided that the first axial end of the pressure return piston is in engagement with an outside of the piston slide, for example with an external, radial protrusion, which is designed, for example, as a circumferential abutment edge on the outside of the piston slide or the cylindrical or ring-like piston slide section . The radial protrusion or the circumferential abutment edge can be designed in one piece with the piston slide or the ring-like piston slide section. Alternatively, it can also be an attached, in particular pressed, ring.

Furthermore, a plurality of such, preferably identically designed pressure return pistons are preferably provided in the piston slide valve, which particularly preferably each have the same radial distance from the longitudinal or central axis of the piston slide valve and / or are evenly distributed in the circumferential direction around the longitudinal axis. For example, two, three, four, six, eight or more such pressure return pistons can be provided, which are then arranged in a correspondingly rotationally symmetrical manner around the longitudinal axis of the piston slide valve. In the simplest case, the multiplicity of pressure return pistons has n-fold rotational symmetry, where n is the number of pressure return pistons.

In a preferred embodiment of the piston slide valve according to the invention, this further comprises one fixed to the valve housing connected guide body, in which preferably all pressure return pistons, preferably exclusively, are guided and / or in which the respective pressure return channels, preferably completely, are formed. The guide body is preferably an annular component arranged concentrically around the longitudinal axis of the piston slide valve and / or in the radial direction on the outside of the cylindrical or ring-like piston slide section, in which preferably all pressure return channels of the piston slide valve are arranged. Correspondingly, the inner radius of the guide body is preferably larger than the outer radius of the ring-like piston slide section. The guide body is preferably designed in one piece and / or as a component that can be inserted into the valve housing.

Furthermore, a plurality of preferably identically designed pressure return channels are preferably provided in the guide body, which - as already described above in connection with the plurality of pressure return channels - particularly preferably each have the same radial distance from the longitudinal or central axis of the piston slide valve and / or in the circumferential direction or are evenly distributed around the longitudinal axis. For example, two, three, four, six, eight or more such pressure return channels can be provided, which are then arranged, for example, rotationally symmetrical about the longitudinal axis of the piston valve or the guide body and / or with parallel longitudinal axes. In the simplest case, the multiplicity of pressure return channels has n-fold rotational symmetry, where n is the number of pressure return channels.

The guide body is directly adjacent to the pressure chamber of the second fluid connection, so that the first channel section of the pressure return channel or the pressure return channels leading the first piston section of the pressure return piston preferably opens directly into this pressure chamber and thereby directly on a surface, preferably on an axially oriented upper or lower section The end face of the guide body ends, so that no separate hydraulic feeds are necessary to apply pressure to the first axial end of the pressure return piston.

Furthermore, hydraulic feeds, for example in the form of bores, are preferably provided in the guide body for the second axial end and the transition section of the pressure return piston. It is particularly preferred that all hydraulic feeds for the second axial end of the pressure return piston or the second channel section of the pressure return channel are provided exclusively in the guide body. In addition, all hydraulic feeds for the pressure return channel are particularly preferably provided exclusively in the guide body, with the exception of an opening in the valve housing for hydraulic connection to the pressure chamber of the first axial fluid connection. Correspondingly, the guide body allows existing valves to be equipped with the above-described pressure return pistons or the corresponding functionality to be retrofitted by providing only minor design changes.

In a preferred embodiment, the piston slide valve according to the invention is also suitable for counter-pressure return, that is to say also for the case that a higher pressure is applied to the first fluid connection than to the second fluid connection. For this purpose, the piston slide valve preferably comprises a counter-pressure return piston which is guided axially displaceably in a counter-pressure return channel and has opposing first and second axial ends which are designed, for example, as flat end faces. The counter-pressure return piston differs from the previously described pressure return piston in that it does not have a transition section, has a constant cross-sectional area at least within the counter-pressure return channel and, in the simplest case, is designed entirely as a cylindrical body. In general, the counter-pressure return piston preferably has exactly one piston section with a cross-sectional area that remains constant in the axial direction at least within the counter-pressure return channel, which in the simplest case is circular, but also - as described above in connection with the pressure return piston - triangular, square, etc. can be. The counter-pressure return channel is accordingly in turn designed to be complementary or corresponding to the pressure return piston. Correspondingly, the counter-pressure return channel preferably consists of precisely one channel section with a corresponding cross-sectional area that remains the same in the axial direction. The first axial end of the counter pressure return piston is hydraulically connected to the first fluid connection and the second axial end of the counter pressure return piston is hydraulically connected to the second fluid connection, the first axial end of the counter pressure return piston being provided to close the piston slide in the direction of an open position urge and accordingly to be in engagement with the piston valve or to come into engagement.

The counter-pressure return channel is advantageously formed in the guide pin, for example in an end face of the guide pin aligned perpendicular to the longitudinal axis of the piston slide valve, and is preferably partially or completely arranged in the first, possibly axial, fluid connection. Furthermore, the counter pressure return duct and the Counter-pressure return piston arranged on the longitudinal axis of the piston slide valve, so that their longitudinal axes coincide with the longitudinal axis of the piston slide valve. Accordingly, the piston slide valve preferably includes exactly one counter pressure return piston. Alternatively, however, a large number of optionally identical and / or rotationally symmetrically arranged counter-pressure return pistons can also be provided. In addition, the counter-pressure return channel and counter-pressure return piston preferably correspond to the pressure return channel and the pressure return piston described above, for example in terms of dimensions.

Correspondingly, the counter-pressure return piston is pushed in the direction of the piston slide and, for example, comes into engagement with an inside of the possibly cup-shaped piston slide in such a way that the piston slide is pushed towards an open position and the free cross section of the fluid channel is increased when the pressure applied to the first fluid connection is greater than the pressure applied at the second fluid connection or when a pressure surge occurs at the first fluid connection. Alternatively, the counter-pressure return piston can also engage or come into engagement with another point of the piston slide, for example another abutment edge, which is preferably arranged in the radial direction on the inside of the guide pin, which simplifies the application of pressure to the counter-pressure return piston. Such a principle of pressure return on both sides is therefore also suitable for applications located inside the shock absorber, in which the valve according to the invention is mounted directly on the piston rod or on and / or in the piston.

A piston slide valve equipped with the counter pressure return piston described above thus allows pressure return in the event of pressure surges both at the first and the second fluid connection, i.e. for both flow directions of the hydraulic fluid, so that the piston slide valve according to the invention can be operated in both flow directions and in a vehicle. Shock absorbers advantageously only have to be provided with a single piston slide valve of this type. Compared to the known provision of two damper valves each assigned to a flow direction, this has the advantage that control electronics do not have to switch the damper valves at a reversal point of the shock absorber movement. In addition, the structural changes compared to conventional valves with a pressure return for only one flow direction, in particular for the flow from the axial fluid connection to the radial fluid connection, are limited to the hydraulic part, in particular the interior of the valve housing, so that the external appearance and the required installation space of the piston valve according to the invention does not differ from conventional valves with a pressure return for only one direction of flow, both in terms of the magnetic drive and in terms of the valve housing and thus in terms of the overall external appearance. In particular, the hydraulic and electrical interfaces can also be designed identically, so that the piston valve according to the invention can easily be exchanged for a conventional valve. The valve according to the invention is preferably mounted directly on the piston rod or on and / or in the piston.

In this piston slide valve according to the invention, depending on the application, it may be necessary for the piston slide valve to be open (normally open, NO valve) or closed (normally closed, NC valve) in a currentless state. The currentless state is also referred to as the fail-safe state, since the piston slide valve assumes this state when it is switched off or when the entire system of the motor vehicle fails, for example when the power supply fails. It can also be desirable for the piston valve to assume a defined intermediate state between “completely closed” and “completely open” in order to achieve an average damping characteristic in the de-energized state instead of an extreme state of the shock absorber. Such valves are for example in the DE 10 2008 035 899 A1 and the disclosure content relating to these embodiments of the valve drive is fully incorporated into the present document.

Furthermore, the piston slide valve according to the invention is preferably designed as a control valve, particularly preferably as a proportional valve.

Figure list

• 1 eine Querschnittsansicht einer Ausführungsform eines Kolbenschieberventils im geöffneten Zustand,
• 2 eine vergrößerte, halbseitige Prinzipdarstellung der Ausführungsform des Kolbenschieberventils im halb-geöffnetem Zustand,
• 3 eine perspektivische Detailansicht von Kolbenschieber und Führungskörper, und
• 4 eine schematische Ansicht eines Stoßdämpfers.

Further advantages of the invention are described below on the basis of the exemplary embodiment explained in the accompanying figures. The exemplary embodiment represents a preferred embodiment which in no way restricts the invention. The figures shown are schematic representations that do not necessarily reflect the real proportions, but rather serve to improve the clarity of the exemplary embodiment. The figures show in detail:

• 1 a cross-sectional view of an embodiment of a piston slide valve in the open state,
• 2 an enlarged, half-page schematic representation of the embodiment of the piston slide valve in the half-open state,
• 3 a perspective detailed view of the piston slide and guide body, and
• 4th a schematic view of a shock absorber.

DETAILED DESCRIPTION

In the 1 to 3 is an embodiment of a piston valve according to the invention 1 for a shock absorber 1a a motor vehicle shown in different views. The valve is an electromagnetically operated piston slide valve 1 with an electrically energizable coil designed to generate an electromagnetic field 2 , two axially movable magnet armatures 3 , 4th and a stationary pole piece 5 as part of the iron circle. The function of the magnet armature 3 , 4th in interaction with two corresponding preload springs 6th , 7th is explained in detail below.

The piston valve 1 has a magnet housing 8th and a valve housing 9 with a lower valve housing part 9a with a first axial fluid connection 11 and an upper valve housing part 9b with a second radial fluid connection 12 on. The fluid connections 11 , 12 are via a fluid channel 13th connected to one another, the free flow cross section of which by means of a piston valve assembly with a piston valve 14th by energizing the coil 2 against a force of the preload spring 6th can be varied by moving the piston valve 14th is shifted axially. The flow cross-section comprising the opening cross-sectional area of the fluid channel 13th can be achieved by means of a ring-like or cylindrical piston slide section 14a of the piston valve 14th that is in the fluid channel 13th can intervene, adjust. For guiding the piston valve 14th or the ring-like piston slide section 14a is a portion of the valve housing part 10a as a guide pin 15th educated. In the guide pin 15th are several radial passage openings 17th provided by the piston valve 14th or its ring-like piston slide section 14a can be closed and opened

1 and 2 show the piston valve 1 in the de-energized state, that is, in the so-called fail-safe position, in which the fluid channel 13th is half-open. This is the first magnet armature 3 with an axially movable plunger 16 firmly connected, for example pressed, on the piston valve 14th works. The first preload spring 6th is supported on the one hand on the lower valve housing 9a , especially the guide pin 15th , and on the other hand on the piston valve 14th and thus pushes the piston valve 14th in an open position in the direction of the plunger 16 . In the in 1 The state shown is in a state of equilibrium between the first prestressing spring 6th and the second bias spring 7th . The second preload spring 7th is between the first magnet armature 3 and the second armature 4th arranged and pushes them apart. To open the piston valve 1 a brief initial current is applied in a manner known per se, so that the first magnet armature 3 on the second magnet armature 4th too moved. If the current supply is increased further, the two armatures move 3 , 4th together on the pole piece 5 to what the piston valve 14th in the direction of the axial fluid connection 11 is shifted and accordingly the radial passage openings 17th locks. It goes without saying that, depending on the application, other linear drives can also be provided in which the valve is open without current (NO, normally open) or closed without current (NC, normally closed).

In the valve body 9 is a concentric guide body 30th provided in which three pressure return pistons 21st in the respective pressure return channels 25th axially displaceably guided radially from the longitudinal axis of the piston valve 1 are spaced apart and are evenly distributed around them, so that the guide body 30th has a threefold rotational symmetry. Each of the three pressure return pistons 21st is a rotationally symmetrical, one-piece component with two cylindrical piston sections each 22a , 22b which have different diameters, and an intermediate transition section 23 , the present as a ring shoulder 23 is trained. The piston sections 22a , 22b extend from the ring shoulder 23 up to the axial ends 24a , 24b of the pressure return piston 21st that as flat end faces 24a , 24b are trained. The pressure return piston is here 21st so arranged and set up radially with its first axial end 24a from the first axial fluid port 11 away or in the direction of an open position of the piston valve 14th points, with an abutment edge 40 of the piston valve 14th to be engaged or to come into engagement to the piston valve 14th to push with a force in the direction of an open position. It points to the first axial end 24a adjacent first piston section 22a a smaller diameter and thus a smaller cross-sectional area than the second piston section 22b on. For example, the diameter of the first piston section is 22a 2 mm and the diameter of the second piston section 22b 2.2 mm, so that there is a difference in diameter of 0.2 mm. The Piston sections 22a , 22b of the pressure return piston 21st are in each case complementary or corresponding channel sections 26a , 26b or through holes of the respective pressure return channel 25th out, which, optionally apart from a clearance fit, each have the same (inner) diameter as the piston sections 22a , 22b . The pressure return duct 25th further has an axially between the channel sections 26a , 26b lying canal transition section 27 on in which the transition section 23 of the pressure return piston 21st is arranged axially displaceable.

To generate the desired actuating force of the pressure feedback piston 21st its axial ends are in 24a , 24b with the hydraulic pressure of the second, radial fluid connection 12 applied and its transition section 23 with the hydraulic pressure of the first, axial fluid connection 11 . The hydraulic pressure of the first, axial fluid connection prevails 11 on the inside of the guide pin 25th and goes to the radial openings 17th to the hydraulic pressure of the second, radial fluid connection 12 about that in the rest of the interior of the valve housing 9 prevails. The first channel section opens 26a of the pressure return duct 25th directly in the pressure chamber of the second, radial fluid connection 12 , which is the first axial end 24a of the pressure return piston 21st already directly with the hydraulic pressure of the radial fluid connection 12 is acted upon and thus with the second, radial fluid connection 12 is hydraulically connected, so that no separate pressure lines or pressure supplies are necessary here. On the other hand is for the hydraulic connection of the second axial end 24b of the pressure return piston 21st with the second, radial fluid connection 12 a radial pressure feed 31 provided in the pressure chamber of the second, radial fluid connection 12 and in the illustrated embodiment completely in the guide body 30th is trained. For the hydraulic connection of the transition section 23 to the first, axial fluid connection 11 is in the guide body 30th an axial pressure feed 32 provided on a through hole 33 of the valve body 9 flows out. Through the through hole 33 becomes the hydraulic pressure of the axial fluid connection 11 on the inside of the valve housing 9 and via the axial pressure feed 32 to the transition section 23 of the pressure return piston 21st directed. The guide body seals accordingly 30th the through hole 33 from, for which purpose sealing means (not shown) are provided.

Is now the hydraulic pressure at the radial fluid connection 12 greater than the hydraulic pressure at the axial fluid connection 11 , so will the pressure return piston 21st due to its different sized hydraulically effective end faces 24a , 24b and the resulting ring shoulder 23 in combination with the described pressurization from the pressure return duct 25th out towards the abutment edge 40 pushed and an actuating force on the piston valve 14th generated in the direction of the open position.

There is also another piston opposite the pressure return piston 21st differently designed, axially displaceable counter-pressure return piston 51 provided on the longitudinal axis of the piston valve 1 is arranged and essentially corresponds to the pressure return piston known in the prior art. The counter pressure return piston 51 is here a completely cylindrical, one-piece component with a single cylindrical piston section 52 which extends to the opposite axial ends 54a , 54b of the counter pressure return piston 51 extends as flat end faces 54a , 54b are formed, and accordingly have the same size. Thereby is the counter pressure return piston 51 so arranged and set up with its first axial end 54a from the first axial fluid port 11 away or in the direction of an open position of the piston valve 14th has, with an inside of the piston valve 14th to be engaged or to come into engagement to the piston valve 14th to push with a force in the direction of an open position. The piston section 52 of the counter pressure return piston 51 is in a complementary or corresponding counter-pressure return channel 56 or through hole 56 out, which is formed in one end face of the guide pin.

Depending on the direction of flow or pressure conditions, either the pressure return pistons 21st or counter-pressure return piston 37 exerts an actuating force on the piston slide 14th generate in opening direction. Thus it becomes a piston valve 1 created, which ensures a pressure return in both directions of flow, which, for example, can create the same pressure-adjusting force characteristic for both directions of flow and at the same time has a simple and compact design, so that no further valves or throttles on the shock absorber 1a are necessary.

In 3 Fig. 3 is a perspective view of the on the lower valve housing part 9a arranged guide body 30th as well as the piston valve 14th shown. There are also two of the three pressure return pistons 21st can be seen from one of the abutment edge 40 of the piston valve 14th facing surface of the guide body 30th exit and with the abutment edge 40 are engaged. The respective radial and axial pressure feeds 31 , 32 as well as the through hole 33 in the lower valve housing part 9a are in 3 covered or not shown. The piston valve 14th shows one cylindrical, ring-like piston valve section 14a and is a cup-shaped component with an essentially closed bottom surface. Around the inside of the cup-shaped piston valve 14th hydraulically with the outside of the piston valve 14th or the radial fluid connection 12 are to be connected in the ring-like piston valve section 14a , for example circular or oval through openings 14b provided, which are dimensioned such that there is no or a negligible dynamic pressure drop. Alternatively, it can also be applied to the bottom surface of the piston valve 14th can be omitted, so that this only consists of the ring-like piston slide section 14a and the bump 40 as well as for example an open support structure for mechanical connection to the plunger. In this alternative embodiment, through openings can then be accessed due to the open support structure 14b be waived.

In 4th is a shock absorber 1a shown, in which a cylinder piston changes the volume of two pressure chambers. On the shock absorber 1a is a piston valve according to the invention 1 attached and via its axial and radial fluid connections 11 , 12 with the shock absorber 1a or its pressure chambers connected. The piston valve 1 is the only throttle between the two pressure chambers of the shock absorber 1a .

List of reference symbols

1

Piston valve

1a

Shock absorbers

2

Kitchen sink

3

first magnet armature

4th

second magnet armature

5

stationary pole piece

6th

first preload spring

7th

second preload spring

8th

Magnet housing

9

Valve body

9a, 9b

lower / upper valve housing part

11

first, axial fluid connection

12th

second, radial fluid connection

13

Fluid channel

14th

Piston valve

14a

ring-like piston section

14b

Through openings

15th

Guide pin

16

Plunger

17th

radial passage opening

21st

Pressure return piston

22a, 22b

cylindrical piston sections

23

Transitional section / ring shoulder

24a, 24b

axial ends / flat end faces

25th

Pressure return duct

26a, 26b

Duct sections

27

Channel transition section

30th

concentric guide body

31

Radial pressure feed

32

Axial pressure feed

33

Through hole

40

Abutment edge

51

Counter pressure return piston

52

cylindrical piston section

54a, 54b

axial ends / flat end faces

56

Counter pressure return duct

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102007058620 B3 [0004]
• DE 102008035899 A1 [0004, 0039]

Claims (15)

Piston slide valve (1), comprising: - a valve housing (9) with a first fluid connection (11) and a second fluid connection (12) and with a fluid channel (13) connecting the two fluid connections, and - a piston slide arrangement with a piston slide (14) of the for changing a free cross section of the fluid channel (13) is axially displaceable, preferably on a guide pin (15) with radial passage openings (17) which can be closed by the piston slide, characterized by at least one pressure return piston (21) axially displaceably guided in a pressure return channel (25) with opposing first and second axial ends (24a, 24b), with a first piston section (22a) with a first cross-sectional area, a second piston section (22b) with a second cross-sectional area, and an intermediate transition section (23), - the first cross-sectional area being smaller is designed as the second cross-sectional area, and - the first e axial end (24a) of the pressure return piston is provided to urge the piston slide (14) in the direction of an open position. Piston valve (1) Claim 1 , characterized in that the first axial end (24a) is in engagement with the piston slide (14) or is designed to be in engagement with the piston slide, preferably on an external radial protrusion of the piston slide, which is particularly preferably a circumferential abutment edge ( 40) is formed and / or is arranged on an annular section (14a) of the piston valve. Piston valve (1) Claim 1 or 2 , characterized in that both axial ends (24a, 24b) of the pressure return piston are hydraulically connected to the second fluid connection (12) and the transition section (23) is hydraulically connected to the first fluid connection (11). Piston slide valve (1) according to one of the preceding claims, characterized in that, when the pressure applied to the second fluid connection (12) is greater than the pressure applied to the first fluid connection (11), the pressure return piston (21) in the direction of the piston slide (14) being pushed. Piston slide valve (1) according to one of the preceding claims, characterized in that the pressure return duct (25) has complementary first and second duct sections (26a, 26b) to the first and second piston sections (22a, 22b), in which the pressure return piston (21 ) is guided in a sealing manner, preferably with a clearance adjustment and / or without a sealing element, as well as an intermediate channel transition section (27) in which the transition section (23) is arranged. Piston slide valve (1) according to one of the preceding claims, characterized in that the piston slide (14) in the open position is at a maximum distance from a first axial end of the piston slide valve (21) and the first fluid connection (11) is closer to the first axial end of the piston slide valve is arranged as the second fluid connection (12), the first fluid connection preferably forming the first axial end of the piston slide valve or being an axial fluid connection and / or the second fluid connection being a radial fluid connection. Piston slide valve (1) according to one of the preceding claims, characterized in that all sections of the interior of the valve housing (9) are hydraulically connected to either the first or the second fluid connection (11, 12) and / or the valve housing is divided into exactly two pressure chambers . Piston slide valve (1) according to one of the preceding claims, characterized in that an interior of the guide pin (15) is hydraulically connected to the first fluid connection (11) and / or an outer space of the guide pin and the piston slide (14), and optionally an interior of the The piston slide, which is located outside the guide pin, is hydraulically connected to the second fluid connection (12). Piston slide valve (1) according to one of the preceding claims, characterized in that the pressure return piston (21) is spaced from a longitudinal axis of the piston slide valve and / or is arranged on an outside of the piston slide (14), preferably a plurality, particularly preferably three, of such pressure return pistons are provided, which particularly preferably have the same radial distance from the longitudinal axis of the piston slide valve and / or are evenly distributed around the longitudinal axis. Piston slide valve (1) according to one of the preceding claims, characterized by a preferably concentric guide body (30), which is firmly connected to the valve housing (9), and / or - in which preferably the pressure return piston (21) or one / the plurality of pressure return pistons is performed and / or the pressure return channel (25) or a plurality of pressure return channels is formed, and / or - in which the first channel section (26a) opens into a surface of the guide body and / or hydraulic feed lines are provided for hydraulically connecting the second channel section (26b) and the channel transition section (27). Piston slide valve (1) according to one of the preceding claims, comprising an electrically energized coil (2) for generating an electromagnetic field and a magnet armature (3) connected to the piston slide and / or characterized in that - the axial ends (24a, 24b) of the Pressure return pistons (21) are designed as flat end faces, - the pressure return piston (21) is rotationally symmetrical, - the piston sections (22a, 22b) of the pressure return piston (s) are designed with cylinder symmetry, - the transition section (23) of the pressure return piston (21) as a shoulder, in particular is designed as an annular shoulder with a flat annular surface, - a diameter difference between the piston sections in the range between 0.01 and 2 mm, and / or - the or all pressure return piston, the valve housing (9) and / or the guide body (30) each are formed in one piece and / or from a single material. Piston slide valve (1) according to one of the preceding claims, characterized by a counter-pressure return piston (51) which is guided axially displaceably in a counter-pressure return channel (56) with opposing first and second axial ends (54), having a piston section (52) with a Cross-sectional area, wherein the first axial end (54a) of the counter-pressure return piston is hydraulically connected to the second fluid connection (12) and the second axial end (54b) of the counter-pressure return piston is hydraulically connected to the first fluid connection (11), and the The first axial end of the counter-pressure return piston is provided to urge the piston slide (14) in the direction of an open position. Piston valve (1) Claim 12 , characterized in that - that the counter-pressure return channel (56) is formed in the guide pin (15), - that the counter-pressure return channel and the counter-pressure return piston (51) are arranged on the longitudinal axis of the piston slide valve, - that the piston slide valve is exactly one Comprises counter-pressure return piston and / or - that the counter-pressure return piston is pushed in the direction of the piston slide when the pressure applied to the first fluid connection (11) is greater than the pressure applied to the second fluid connection (12), so that the free cross section of the fluid channel (13) is enlarged. Piston slide (14) for a piston slide valve (1) according to one of the preceding claims, characterized by an annular piston slide section (14a) for moving on a guide pin (15) and with an external radial protrusion, which is preferably designed as a circumferential abutment edge (40), wherein the radial protrusion and / or the circumferential abutment edge is formed in one piece with the ring-like piston slide section or the piston slide or the circumferential abutment edge is a pressed-on ring. Shock absorber (1a) for a vehicle, having one, preferably exactly one, piston slide valve (1) according to one of the Claims 1 to 13th , wherein the piston slide valve is particularly preferably the only throttle between the damper chambers of the shock absorber and / or the piston slide valve is mounted directly on a piston rod or on and / or in a piston.

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