Electromagnetic valve for short switching times

Abstract

Electromagnetic seat valve including: 1.1 a valve housing (1-15) with a valve chamber (10) into which a first chamber inlet (11) and a second chamber inlet (12) for a fluid open, 1.2 a valve seat (4) through which the first chamber access (11) opens into the valve chamber (10) and which rotates around a valve axis (L), 1.3 a closing element (20) which is movable back and forth in an axial direction (±X) in a closing direction (X) up to a closing position in which it is in sealing contact with the valve seat (4) and separates the first chamber access (11) from the second chamber access (12), and in a releasing direction (-X) up to a releasing position in which it releases the valve seat (4), and 1.4 an electrical coil (35) and an armature (30) movable back and forth in the axial direction (±X) to generate an actuating force that acts in the axial direction (±X) on the closing element (20), 1.5 wherein the locking element (20) has a locking element cavity (21) extending through the locking element (20) from a front cavity opening axially facing the first chamber access (11) to a rear side of the locking element (10) axially away from the first chamber access (11), and / or 1.6 wherein the anchor (30) has an anchor cavity (31) extending through the anchor (30) from a front side of the anchor (20) pointing axially towards the first chamber access (11) to a rear cavity opening at a rear side of the anchor (20) facing axially away from the first chamber access (11), characterized in that 1.7 the seat valve comprises a spring device (25) for generating a spring force acting against the closing element (20) and the actuating force, wherein 1.8 the locking element (20) has a spring support (22) consisting of several support elements projecting locally outwards on the outer circumference of the locking element (20), on which the spring device (25) is axially supported.

Description

[0001] The invention relates to an electromagnetic valve for controlling or regulating a fluid. The valve can be used in vehicle construction, particularly in a servo system for hydraulic steering assistance. However, the invention can also be used in other servo systems or fluid systems in general, both in and outside of vehicle construction.

[0002] Electromagnetically actuated quick-switching valves for controlling an inlet volume flow for a hydraulic displacer are known from the prior art, for example from German patent application DE 10 2009 022 974 A1. Alternatively, German patent application DE 10 2015 116 909 A1 describes an electromagnetic switching valve for opening or closing an oil or coolant circuit in a motor vehicle.

[0003] Many applications require fast switching times. This requirement is particularly high in safety-relevant hydraulic systems, such as hydraulically assisted steering systems in vehicles.

[0004] It is therefore an object of the invention to provide a valve with a short switching time.

[0005] A valve that can be switched between blockage and flow within a very short time is desirable.

[0006] Another or further task can be seen in creating a valve that is suitable for use in a hydraulic power steering system, for example as a backup valve to neutralize the power steering in an emergency, such as a power outage.

[0007] The invention relates to an electromagnetic valve in the form of a poppet valve. The valve comprises a valve housing with a valve chamber into which a first chamber inlet and a second chamber inlet for a fluid open. The fluid can, in particular, be a hydraulic fluid. The first chamber inlet opens into the valve chamber via a valve seat. The valve seat rotates about a valve axis and simultaneously defines the valve axis. The valve further comprises a closing element that is axially movable back and forth in a closing direction up to a closed position in which it is in sealing contact with the valve seat and separates the first chamber inlet from the second chamber inlet, and in a releasing direction up to a releasing position in which it releases the valve seat. The closing element can be linearly movable in both the closing and releasing directions.However, it should not be ruled out that the closing element, in addition to its axial movement, also performs a radial movement relative to the valve axis, for example by being pivotable. The term "movable in the axial direction" therefore also includes designs in which the closing element is movable with an axial directional component and a directional component radial to the valve axis, the axial component preferably being larger than the radial component.

[0008] Further components of the valve include an electrical coil and an axially movable armature to generate an actuating force that can be applied to the closing element, i.e., the force acts on the closing element via the armature. For this purpose, the armature is coupled to the closing element. The armature can be coupled to the closing element, in particular, by simple axial pressure contact, thus in a pure stop contact. However, the closing element and the armature can also be connected by a material connection or frictional connection. The closing element and the armature can be coupled via one or more intermediate elements. Advantageously, however, they are coupled directly, for example, by direct axial stop contact.

[0009] The valve axis surrounded by the valve seat can be a central axis of the valve seat and / or the coil and / or the armature. In the closed position, the closing element separates the valve chamber from the first chamber access. The second chamber access can be permanently connected to the valve chamber. The first chamber access leads axially into the valve chamber; that is, it opens axially into the valve chamber as soon as the closing element moves out of sealing contact with the valve seat. The second chamber access can open laterally into the valve chamber, in a direction transverse to the valve axis. It can be located, in particular, on a section of the valve body surrounding the valve chamber. The valve body can have only a single second chamber access or several second chamber accesses.The multiple secondary chamber inlets can be arranged at circumferential intervals on the outer section of the valve housing and thus open into the valve chamber at several points. Each of these secondary chamber inlets can be permanently connected to the valve chamber.

[0010] According to the invention, the locking element has a locking element cavity and / or the anchor has an anchor cavity. If the locking element has the locking element cavity, this extends from a front cavity opening, which faces axially towards the first chamber access, to a rear side of the locking element facing axially away from the first chamber access, through the locking element. The locking element cavity opens into the first chamber access at its front cavity opening and opens at its other end at the rear side of the locking element. If the anchor has the anchor cavity, this extends from a front side of the anchor facing axially towards the first chamber access to a rear cavity opening through the anchor. The anchor has the rear cavity opening at a rear side facing axially away from the first chamber access. The anchor cavity thus opens at the front and rear sides of the anchor. The respective cavity, i.e.,The closing element cavity and / or the armature cavity thus forms a passage. Because the closing element and / or the armature are designed as hollow bodies in this sense, mass is accumulated in the respective element, so that under the influence of a given axial force, the acceleration in the direction of the axial force is increased and the reaction time or switching time for the valve to change between the closed and open states is reduced.

[0011] In preferred embodiments, the closing element has a closing element cavity and the anchor has an anchor cavity. In such embodiments, it is further advantageous if a uniform cavity, comprising the closing element cavity and the anchor cavity, extends axially and continuously through the closing element and the anchor. The uniform cavity can open into the first chamber access at the front cavity opening of the closing element and into a rear housing chamber of the valve housing at the rear cavity opening of the anchor, so that the uniform cavity connects the first chamber access with the rear housing chamber. Advantageously, this connection exists when the closing element is in the closed position. The first chamber access can also be connected to the rear housing chamber via the uniform cavity when the closing element is in the released position.Preferably, the first chamber access and the rear housing space are always connected via the uniform cavity, regardless of the position of the locking element.

[0012] In further developments, the locking element and the anchor are components of an axially translational motion unit that has a uniform cavity encompassing the locking element cavity and / or the anchor cavity. The motion unit can include one or more additional elements, for example, a transmission element arranged axially between the locking element and the anchor and / or an element arranged on the rear side of the anchor. Preferably, however, the locking element and the anchor alone constitute the motion unit. "Axially translational motion unit" means that the elements, combined into the motion unit by suitable coupling, perform axial translational movements together.

[0013] In advantageous embodiments, the uniform cavity of the motion unit extends from the front cavity opening of the locking element to a rear cavity opening on the back side of the motion unit, axially opposite the first chamber access, through the motion unit. In such embodiments, the uniform cavity is a passage extending through the motion unit, which advantageously connects the first chamber access with the aforementioned rear housing space. The front cavity opening of the locking element is also the front cavity opening of the motion unit. The rear cavity opening of the motion unit can, in particular, be the rear cavity opening of the anchor. The uniform cavity already mentioned above in relation to the locking element and anchor can form the uniform cavity of the motion unit.

[0014] If both the locking element and the armature are formed as hollow bodies, even more mass can be saved compared to designs in which only the locking element or only the armature is hollow, and consequently the switching time required for reversing can be further reduced. By forming a single cavity connecting the first chamber access with the rear housing space, the locking element and the armature can be balanced with respect to axial fluid pressure, so that the two elements, which are preferably combined into a single moving unit, can move back and forth without axial differential pressure. A combination of both features—namely, the reduction in mass and the design for minimal differential pressure, preferably zero differential pressure—not only results in short switching times but also contributes to reducing the force required to move the locking element.Furthermore, the switching time and the required force are not affected, or at most only to a practically irrelevant extent, by the fluid pressure prevailing at the respective chamber access.

[0015] With regard to inertia, it is advantageous if the locking element has a total volume, measured overall, that is at most four times, or preferably at most three times, the volume of the locking element cavity. With regard to the anchor, it is advantageous if the anchor has a total volume, measured overall, that is at most five times, or preferably at most four times, the volume of the anchor cavity. If the locking element and the anchor are part of a single motion unit, it is advantageous if the motion unit has a total volume, measured overall, that is at most five times, or preferably at most four times, the volume of the unified cavity.A cavity formed as a passageway for a closing element and / or anchor cavity and / or a uniform cavity contributes not only to the reduction of inertia but also to the reduction of the flow resistance of the respective element or moving unit.

[0016] For short switching times, it is advantageous if the first chamber access has a large cross-sectional area axially at the level of the valve seat, so that a large cross-sectional area is established in the axial direction between the valve seat and a closing surface of the closing element, even with a small stroke of the closing element. It is also advantageous that the stroke length of the closing element from the closed position to the release position can be short. The closing surface is a surface on the front of the closing element where, in the closed position, the closing element is in sealing contact with the valve seat. This sealing contact can be almost linear.

[0017] If K denotes the diameter of a circular area whose size corresponds to the flowable cross-sectional area of ​​the first chamber access axially at the level of the valve seat, and H denotes the length of the stroke that the closing element executes when moving from the closed position to the open position, then K ≥ 3 · H or K ≥ 4 · H is advantageously the case. The flowable connection cross-section, which opens immediately after the sealing contact is released and increases during the open movement until it reaches its nominal size in the open position of the closing element, has the form of an annular strip circumferentially around the valve axis. The circumferential area of ​​the annular strip can serve as a measure of the size of the connection cross-section. The size of the connection cross-section is therefore proportional to the product of the equivalent diameter K and the stroke length H.The larger the equivalent diameter K is, the greater the increase in the connection cross-section per unit of stroke length, and the smaller the stroke length can be until the release position is reached, given a nominal size of the connection cross-section.

[0018] The locking element surrounds the locking element cavity, if present, with an inner circumference. Advantageously, this inner circumference can extend smoothly and cylindrically in the axial direction over the entire length of the locking element cavity. This does not, of course, preclude the locking element's inner circumference from terminating with a short axial chamfer directly at the front cavity opening and / or at the rear end of the locking element. In this sense, the locking element cavity can be cylindrical over its entire length, for example, circular. The locking element cavity can have the same cross-section over its entire length.

[0019] The anchor surrounds the anchor cavity, if present, with an inner circumference. Advantageously, the inner circumference of the anchor can extend smoothly and cylindrically in the axial direction over at least the majority of the anchor's axial length. This does not, of course, preclude the inner circumference from terminating with a short axial chamfer directly at a cavity opening on the front of the anchor and / or directly at the rear cavity opening. In this sense, the anchor cavity can be cylindrical, for example, circular-cylindrical, over at least the majority of the anchor's axial length. The anchor cavity can have the same cross-section over at least the majority of the anchor's axial length.

[0020] The locking element and / or the anchor can each be sleeve-shaped. The locking element and / or the anchor can therefore be a sleeve body.

[0021] If the locking element is sleeve-shaped, it has a sleeve wall with an outer diameter that is several times greater than the wall thickness of the sleeve wall along the axial length of the locking element. Preferably, the outer diameter is everywhere at least four or five times greater than the wall thickness of the sleeve wall of the locking element. If the locking element is circular cylindrical over its outer circumference, the outer diameter of the locking element corresponds to the diameter of the outer circumference. Otherwise, the smallest outer diameter in the respective cross-section of the locking element is used for comparison. The locking element cavity has a diameter that is advantageously at least twice or at least three times greater than the wall thickness of the sleeve wall of the locking element along the axial length of the locking element. If the locking element cavity is circular cylindrical, the diameter of the locking element cavity corresponds to the diameter of the locking element cavity.Otherwise, the smallest width of the locking element cavity in the respective cross-section of the locking element will be used for comparison.

[0022] If the anchor is sleeve-shaped, it has a sleeve wall with an outer diameter that is several times greater than the wall thickness of the sleeve wall along the axial length of the anchor. Preferably, the outer diameter is everywhere at least three or four times greater than the wall thickness of the anchor's sleeve wall. If the anchor is circular cylindrical over its outer circumference, the outer diameter of the anchor corresponds to the diameter of the outer circumference. Otherwise, the smallest outer diameter in the respective cross-section of the anchor is used for comparison. The anchor cavity has a diameter that is advantageously at least 1.5 times or at least twice the wall thickness of the anchor's sleeve wall along the axial length of the anchor. If the anchor cavity is circular cylindrical, the diameter of the anchor cavity corresponds to the diameter of the anchor cavity. Otherwise, the smallest diameter of the anchor cavity in the respective cross-section of the anchor is used for comparison.

[0023] The anchor cavity can advantageously widen radially towards the rear cavity opening and, via the resulting widening, open into a rear housing chamber of the valve housing. The widening can be arcuate, concave, bell-shaped, or advantageously funnel-shaped. It can also be arcuate, convex, trumpet-shaped, or, in particular, conical. Preferably, it is continuously smooth along its entire length, i.e., without discontinuities. The widening is not simply a chamfer, but a pronounced expansion to enlarge the anchor cavity in the rear cavity region. In advantageous embodiments, the widening extends over at least 5%, at least 10%, or at least 15% of the total axial length of the anchor.On the other hand, with regard to the electromagnetic field strength and thus the actuating force, it is advantageous if the expansion extends only over a maximum of half or at most one-third of the total axial length of the anchor. The anchor cavity expediently expands to just before the rear cavity opening and has its largest cross-section at the rear end of the anchor. Advantageously, the cavity cross-section immediately at the rear cavity opening is at least 50% or at least 100% larger than in an anchor section axially upstream of the expansion. The expansion reduces the flow resistance that the anchor offers to movement in the release direction.

[0024] If the locking element and the armature are part of an axially translational motion unit, they can advantageously be coupled within the motion unit by an axial stop contact that acts in both the closing and release directions. Preferably, they are directly connected to each other in the stop contact. The actuating force can be directed such that it pushes the armature towards the locking element, preferably directly against the locking element.

[0025] According to the invention, the valve comprises a spring assembly for generating a spring force that acts on the closing element in the opposite direction to the actuating force. The spring assembly can be axially supported on the armature, so that the spring force acts directly on the armature and, via the armature, on the closing element. Preferably, however, the spring assembly is axially supported on the closing element, so that the spring force acts directly on the closing element. If the closing element and the armature are coupled by an axial stop contact, they are pressed towards each other by the spring force, preferably directly against each other.

[0026] The actuating force can act in the release direction, and the spring force accordingly in the closing direction. However, it is preferred that the actuating force acts in the closing direction and the spring force in the release direction on the closing element. In preferred embodiments, the actuating force presses the closing element against the spring force into a tight seal with the valve seat. If the actuating force fails due to a malfunction, such as a power failure, the closing element lifts off the valve seat due to the continuing spring force and moves into the release position, thus performing a release stroke.

[0027] The spring assembly can surround the closing element. This allows the use of a spring with a large cross-sectional area and is also advantageous with regard to short overall lengths. The spring assembly can be housed within the valve chamber, which facilitates a slim valve design. The spring assembly can comprise one or more springs. In simple, and therefore preferred, embodiments, a single spring forms the spring assembly. The spring assembly can include a helical compression spring or, advantageously, be designed entirely as a helical compression spring.

[0028] The spring assembly, preferably a single spring, can be axially supported on the closing element, so that the spring force acts directly on the closing element via a spring support of the closing element. According to the invention, the closing element, in the form of the spring support, has several support elements on its outer circumference that project only locally outwards, against which the spring assembly is axially supported. The support elements can each project radially outwards into the valve chamber in a wing-like manner. For example, three or more local support elements can project in a wing-like manner. The support elements are preferably arranged in a circumferentially equal distribution, i.e., at equal angular intervals from one another. The maximum circumferential extent of each support element is advantageously smaller than the circumferentially measured distance between any two circumferentially adjacent support elements.The smaller the increase in the cross-sectional area of ​​the closing element associated with the spring support, the smaller the increase in the flow resistance of the closing element associated with the spring support.

[0029] In advantageous embodiments, the valve housing forms an axial sliding guide for the closing element. The valve chamber can be sealed via the sliding guide, i.e., in the sliding contact between the closing element and the sliding guide. Alternatively, or preferably additionally, the valve housing can form an axial sliding guide for the armature. The armature and the armature sliding guide can form a sealing gap in their sliding contact. Advantageously, the valve housing forms a sliding guide for both the closing element and the armature, wherein the inner and outer circumferential surfaces in sliding contact are advantageously matched to each other to also form a sealing gap in the area of ​​the respective sliding guide.

[0030] The valve can be used, in particular, as a safety valve in a hydraulic system to assist the steering of a vehicle. In this application, a particularly short valve switching time is required.

[0031] The invention relates to the valve itself and also to a hydraulic system for assisting the steering of a vehicle. The hydraulic system comprises a double-acting piston-cylinder assembly with a cylinder and a piston arranged axially within the cylinder between a first cylinder port and a second cylinder port. The piston divides the cylinder into a first cylinder chamber, into which the first cylinder port opens, and a second cylinder chamber, into which the second cylinder port opens. The piston-cylinder assembly is arranged in the vehicle's steering system between the steering element, which is, for example, the steering wheel, and the wheels to be actuated, in order to hydraulically assist the manual steering forces. The two cylinder chambers are also referred to as steering chambers. The hydraulic system includes a valve according to the invention. The first cylinder chamber is connected to the first chamber inlet of the valve via the first cylinder port.The second cylinder chamber is connected to the second chamber inlet or inlets of the valve via the second cylinder port. When the closing element assumes the release position, the two cylinder chambers of the piston-cylinder assembly are short-circuited via the valve. In the release state of the valve, the pressure in the two cylinder chambers of the piston-cylinder assembly equalizes. This neutralizes the hydraulic power steering and prevents it from interfering with the driver's manual steering movements.

[0032] Features of the invention are also described in the aspects formulated below.

[0033] The aspects are formulated in the manner of claims and can replace them. Features disclosed in the aspects can further supplement and / or qualify the claims, show alternatives to individual features, and / or extend claim features. Reference numerals in parentheses refer to an embodiment of the invention illustrated in subsequent figures. They do not restrict the features described in the aspects to their literal meaning as such, but rather indicate preferred ways of realizing the respective feature and also subject matter for divisional applications. 1. Electromagnetic seat valve comprising: 1.1 a valve housing (1-15) with a valve chamber (10) into which a first chamber inlet (11) and a second chamber inlet (12) for a fluid open, 1.2 a valve seat (4) through which the first chamber access (11) opens into the valve chamber (10) and which rotates around a valve axis (L), 1.3 a closing element (20) which is movable back and forth in an axial direction (±X) in a closing direction (X) up to a closing position in which it is in sealing contact with the valve seat (4) and separates the first chamber access (11) from the second chamber access (12), and in a releasing direction (-X) up to a releasing position in which it releases the valve seat (4), and 1.4 an electrical coil (35) and an armature (30) movable back and forth in the axial direction (±X) to generate an actuating force that acts in the axial direction (±X) on the closing element (20), 1.5 wherein the locking element (20) has a locking element cavity (21) which extends through the locking element (20) from a front cavity opening axially towards the first chamber access (11) to a rear side of the locking element (10) axially away from the first chamber access (11), and / or 1.6 wherein the anchor (30) has an anchor cavity (31) extending through the anchor (30) from a front side of the anchor (20) facing axially towards the first chamber access (11) to a rear cavity opening at a rear side of the anchor (20) facing axially away from the first chamber access (11), characterized by the fact that 1.7 the seat valve comprises a spring device (25) for generating a spring force acting against the closing element (20) and the actuating force, wherein 1.8 the locking element (20) has a spring support (22) consisting of several support elements projecting locally outwards on the outer circumference of the locking element (20), on which the spring device (25) is axially supported. 2. Electromagnetic valve according to the preceding aspect, wherein a uniform cavity (21, 31) extends axially through the closing element (20) and the armature (30), comprising the closing element cavity (21) and the armature cavity (31). 3. Electromagnetic valve according to the preceding aspect, wherein the uniform cavity (21, 31) opens at the front cavity opening of the closing element (20) into the first chamber access (11) and at a rear cavity opening into a rear housing space (13), so that the uniform cavity (21, 31) connects the first chamber access (11) with the rear housing space (13). 4. Electromagnetic valve according to the preceding aspect, wherein the rear cavity opening opens at the rear of the armature (30). 5. Electromagnetic valve according to any of the preceding aspects, wherein the closing element (20) has a total volume measured overall and this total volume is at most 4 times or at most 3 times the volume of the closing element cavity (21). 6. Electromagnetic valve according to one of the preceding aspects, wherein the armature (30) has a total volume measured overall and this total volume is at most 5 times or at most 4 times the volume of the armature cavity (31). 7. Electromagnetic valve according to one of the preceding aspects, wherein the closing element (20) and the armature (30) are part of an axial translational motion unit (20, 30) which has a uniform cavity (21, 31) comprising the closing element cavity (21) and / or the armature cavity (31). 8. Electromagnetic valve according to the preceding aspect, wherein the uniform cavity (21, 31) extends from the front cavity opening of the closing element (10) through the motion unit (20, 30) to a rear cavity opening at a rear side of the motion unit (20, 30) axially opposite the first chamber access (11), and connects the first chamber access (11) to a rear housing space (13) at the rear of the motion unit (20, 30). 9. Electromagnetic valve according to the preceding aspect, wherein the moving unit (20, 30) has a total volume measured overall and within the total volume the unit cavity (21, 31) and the total volume is at most 5 times or at most 4 times the volume of the unit cavity (21, 31). 10. Electromagnetic valve according to one of the preceding aspects, wherein the armature (30) has the rear cavity opening. 11. Electromagnetic valve according to one of the four immediately preceding aspects, wherein the motion unit (20, 30) is balanced with respect to axial fluid pressure. 12. Electromagnetic valve according to one of the five immediately preceding aspects, wherein the closing element (20) and the armature (30) together form the movement unit (20, 30). 13. Electromagnetic valve according to one of the preceding aspects, wherein the closing element (20) has an inner circumference that surrounds the closing element cavity (21) and extends cylindrically smooth in the axial direction over the entire length of the closing element cavity (21). 14. Electromagnetic valve according to one of the preceding aspects, wherein the closing element cavity (21) is cylindrical over its entire length and has the same cross-section. 15. Electromagnetic valve according to one of the preceding aspects, wherein the armature (30) has an inner circumference that surrounds the armature cavity (31) and extends cylindrically smooth in the axial direction at least over the predominant part of the axial length of the armature (30). 16. Electromagnetic valve according to one of the preceding aspects, wherein the closing element (20) and / or the armature (30) is or are sleeve-shaped. 17. Electromagnetic valve according to any of the preceding aspects, wherein the closing element (20) has a jacket surrounding the closing element cavity (21) and the closing element cavity (21) has a smallest radial width (d) in each cross-section of the closing element (20). S ) exhibits a thickness that is at least twice or at least three times greater than the greatest wall thickness of the surrounding mantle in the same cross-section of the closing element (20). 18. Electromagnetic valve according to one of the preceding aspects, wherein the armature (30) has a shell surrounding the armature cavity (31) and the armature cavity (31) has a smallest radial width (d) in each cross-section of the armature (30). A ) which is larger, preferably at least 50% larger than a maximum wall thickness of the surrounding mantle in the same cross-section of the anchor (30). 19. Electromagnetic valve according to one of the preceding aspects, wherein the armature cavity (31) widens radially, for example conically, in a rear cavity section (32) towards the rear cavity opening. 20. Electromagnetic valve according to the preceding aspect, wherein the armature cavity (31) widens radially to the rear cavity opening. 21. Electromagnetic valve according to one of the two immediately preceding aspects, wherein the armature cavity (31) widens continuously in a funnel shape, for example conically, over the length of the rear cavity section (32) to the rear cavity opening. 22. Electromagnetic valve according to one of the three immediately preceding aspects, wherein the armature cavity (31) extends over a length of at least 10% of the total length of the armature (30). 23. Electromagnetic valve according to one of the four immediately preceding aspects, wherein the armature cavity (31) widens to a largest cavity cross-section and the armature (30) has an outer circumference axially at the level of the largest cavity cross-section with an outer circumferential cross-section which is at most 1.5 times larger than the largest cavity cross-section. 24. Electromagnetic valve according to one of the preceding aspects, wherein the first chamber access (11) has a flowable cross-sectional area axially at the level of the valve seat (4) which corresponds in size to a circular area with diameter K, and the closing element (20) executes a stroke of length H when moving from the closed position to the release position, wherein: K≥3•H or K≥4•H. 25. Electromagnetic valve according to one of the preceding aspects, wherein the release position is an end position specified by a stop contact. 26. Electromagnetic valve according to one of the preceding aspects, wherein the closing element (20) and the armature (30) are part of an axial translational motion unit (20, 30) and are coupled in the motion unit (20, 30) by an axial stop contact which acts in the closing direction (X) and the releasing direction (-X). 27. Electromagnetic valve according to one of the preceding aspects, wherein the actuating force pushes the armature (30) in the direction of the closing element (20), preferably directly against the closing element (20). 28. Electromagnetic valve according to one of the preceding aspects, wherein the actuating force in the closing direction (X) and the spring force in the releasing direction (-X) act on the closing element (20). 29. Electromagnetic valve according to one of the two immediately preceding aspects, wherein the spring force pushes the closing element (20) and the armature (30) towards each other in an axial direction, preferably against each other. 30. Electromagnetic valve according to one of the three immediately preceding aspects, wherein the spring assembly (25) surrounds the closing element (20). 31. Electromagnetic valve according to one of the four immediately preceding aspects, wherein the spring device (25) is axially supported on the closing element (20). 32. Electromagnetic valve according to the preceding aspect, wherein a gap remains between adjacent support elements in the circumferential direction and the support elements define an annular area in an axial view of the closing element (20) which extends radially outwards from the outer circumference of the closing element (20), from which the support elements project, to an envelope that encloses the support elements and follows the course of the outer circumference of the closing element (20), and wherein the annular area in the axial view is at least three times or at least four times as large as the sum of the areas of the support elements. 33. Electromagnetic valve according to the preceding aspect, wherein the annular area is a circular annular area. 34. Electromagnetic valve according to each of the preceding aspects in combination with aspect 28, wherein the spring device (25) is a helical compression spring. 35. Electromagnetic valve according to one of the preceding aspects, wherein the valve body (1-15) forms an axial closing element sliding guide (2) for the closing element (20). 36. Electromagnetic valve according to the preceding aspect, wherein the valve chamber (10) is sealed via the closing element sliding guide (2). 37. Electromagnetic valve according to one of the preceding aspects, wherein the valve body (1-15) forms an axial armature sliding guide (9) for the armature (30). 38. Electromagnetic valve according to the preceding aspect, wherein the armature (30) and the armature sliding guide (7) form a sealing gap in the sliding contact. 39. Electromagnetic valve according to one of the two immediately preceding aspects, wherein the armature (30) has a pressure equalization opening (33) connecting the armature cavity (21) to an equalization chamber (14) on the outer circumference of the armature (30). 40. Electromagnetic valve according to the preceding aspect, wherein the compensation chamber (14) extends annularly around the armature (30). 41. Electromagnetic valve according to one of the two immediately preceding aspects in combination with aspect 37, wherein the compensation space (14) is located axially between the closing element slide guide (2) and the armature slide guide (7). 42. Electromagnetic valve according to one of the five immediately preceding aspects, wherein the valve body (1-15) comprises a pressure sleeve (8) with a guide section forming the armature sliding guide (7), and wherein the pressure sleeve (8) closes off a rear housing space (13) into which the rear cavity opening of the armature (30) opens. 43. Electromagnetic valve according to the preceding aspect, wherein the valve body (1-15) comprises a valve chamber body (1) surrounding the valve chamber (10) and having the second chamber access (12) on a circumference. 44. Electromagnetic valve according to one of the preceding aspects, wherein the closing element (20) has a smooth cylindrical outer circumference over at least the majority of its length. 45. Electromagnetic valve according to one of the preceding aspects, wherein the armature (30) has a smooth cylindrical outer circumference over at least the predominant part of its length, preferably over its entire length. 46. ​​Electromagnetic valve according to one of the preceding aspects, wherein the valve body (1-15) has a valve chamber body (1) with a jacket section surrounding the valve chamber (10) and the valve seat (4) and having the second chamber access (12) on a circumference. 47. Electromagnetic valve according to the preceding aspect, wherein the valve seat (4) is offset in the axial direction (±X) to the second chamber access (12) by less than one maximum axial width of the second chamber access (12). 48. Electromagnetic valve according to one of the two immediately preceding aspects, wherein the jacket section forms a nozzle-like valve connection. 49. Electromagnetic valve according to the preceding aspect in combination with aspect 28, wherein the spring device (25) is supported in the axial direction (X) on the bushing (3). 50. Electromagnetic valve according to one of the preceding aspects, wherein the closing element (20) has a closing surface (24) with which it bears in sealing contact against the valve seat (4) in the closed position, and has a radial expansion (23) on the outer circumference in the valve chamber (10), the closing surface (24) in the valve chamber (10) projects radially outwards over the valve seat (4) in the closed position, and the expansion (23) forms a compensating surface for the outwardly projecting part of the closing surface (24) in order to compensate the closing element (20) in the closed position with respect to the axial direction (±X) in pressure. 51. Electromagnetic valve according to one of the preceding aspects, wherein the closing element (20) has a closing surface (24) with which it bears in the closed position with sealing contact against the valve seat (4), and in the valve chamber (10) has a radial expansion (23) on the outer circumference with which it bears in the release position in the release direction (-X) with axial stop contact against a stop of the valve body (1-15), thereby determining the release position. 52. Electromagnetic valve according to one of the preceding aspects, wherein the valve body (1-15) has a stop (16) against which the closing element (20) rests in the release position in the release direction (-X) with axial stop contact, thereby determining the release position. 53. Electromagnetic valve according to the preceding aspect in combination with aspect 37, wherein the valve body (1-15) widens from the closing element slide guide (2) in the closing direction (X) via an annular shoulder into the valve chamber (10) and the annular shoulder forms the stop (16). 54. Electromagnetic valve according to one of the two immediately preceding aspects, wherein the spring support (22) according to aspect 33 and / or the radial expansion (23) according to aspect 52 forms or form a counter stop of the closing element (20). 55. Electromagnetic valve according to one of the preceding aspects, used as a safety valve (V) in a hydraulic system to assist the steering of a vehicle. 56. Hydraulic system to assist the steering of a vehicle, the hydraulic system comprising: (a) a cylinder (40) with a first cylinder port and a second cylinder port, (b) a piston (41) arranged axially between the cylinder ports in the cylinder (40), (c) and a valve (V) according to one of the preceding aspects, (d) wherein the first chamber access (11) is connected to the first cylinder port and the second chamber access (12) is connected to the second cylinder port, so that the piston (41) can be subjected to the same pressure on both sides via the valve (V). 57. Hydraulic system according to the preceding aspect, comprising a pump (41) connected to the first cylinder chamber and the second cylinder chamber and configured to selectively apply hydraulic pressure to the first cylinder chamber and the second cylinder chamber, wherein the valve (V) and the pump are arranged in parallel.

[0034] An embodiment of the invention is explained below with reference to the figures. Features that become apparent in the embodiment, individually and in every combination, constitute the subject matter of the claims and aspects, as well as the embodiments and advantages further explained above. The figures show: Fig. 1 an electromagnetic valve in an isometric view, Fig. 2 the valve in a side view, Fig. 3 the valve in a longitudinal section, Fig. 4 a closing element of the valve in an isometric view, Fig. 5 the locking element in a longitudinal section, Fig. 6. An anchor of the valve in a longitudinal section, and Fig. 7 a hydraulically assisted steering system of a vehicle.

[0035] The Fig. 1, Fig. 2 to Fig. Figure 3 shows an embodiment of a valve V according to the invention in an isometric view, a side view, and a longitudinal section. The longitudinal section plane AA of the Fig. 3 is in Fig. 2 entered. The valve V comprises a multi-part valve body, of which in the Fig. 1 and Fig. 2. A valve chamber housing 1, a coil housing 5, and a bracket 7 are visible. The bracket 7 is firmly joined to the valve chamber housing 1. It surrounds the coil housing 5 and thus connects the coil housing 5 immovably to the valve chamber housing 1, for example by clamping, in order to form the valve housing as a single assembly unit. A coil connection 36 formed on the coil housing 5 is also visible.

[0036] The valve chamber housing 1 projects axially from the coil housing 5 and the bracket 7, i.e., parallel to a valve axis L of the valve V. The valve chamber housing 1 forms a hydraulic fluid connection in the form of a connecting nozzle. This connecting nozzle surrounds an axially extending first chamber inlet 11, which opens at a front end face of the valve chamber housing 1, and several second chamber inlets 12, which are arranged circumferentially spaced apart from one another around the circumference of the connecting nozzle.

[0037] The valve V is an electromagnetic poppet valve. It comprises a closing element 20 which is movable back and forth along the valve axis L in an axial closing direction X and an axial release direction -X between a closed position and a release position within the valve housing, in particular within the valve chamber housing 1. The closed position is determined by the stop and sealing contact of the closing element 20 with a valve seat 4, and the release position is determined by the stop contact of the closing element 20 with a rear stop 16 of the valve housing.

[0038] In Fig. 3 The closing element 20 assumes the closed position, in which it is in sealing contact with the valve seat 4 of the valve housing and separates the first chamber inlet 11 from the second chamber inlets 12. An electromagnetic actuator, comprising an axially movable armature 30 and a coil 35, generates an actuating force that acts on the closing element 20 via the armature 30 in the closing direction X. A spring assembly 25 generates a spring force that acts opposite to the actuating force in the release direction - X. In normal operation, the actuating force is greater than the spring force and holds the closing element 20 in the closed position against the permanently acting spring force. If the actuating force is reduced by a corresponding amount or if the actuating force ceases entirely, for example in the event of a power failure, the valve V switches from the closed state to the release state.The closing element 20 lifts off the valve seat 4 and moves in the release direction -X until it reaches the release position. During this release movement, and particularly in the release position, the closing element 20 exposes a connecting cross-section through which the first chamber inlet 11 is then connected to the second chamber inlets 12. In the closed position, the closing element 20 closes this connecting cross-section, thereby separating the first chamber inlet 11 from the second chamber inlets 12.

[0039] The locking element 20 and the armature 30 are coupled by an axial stop contact. In the stop contact, the actuating force pushes the armature 30 in the closing direction X against the locking element 20, and the spring force pushes the locking element 20 in the release direction -X against the armature 30. Due to this coupling, the locking element 20 and the armature 30 perform axial movements together and thus form an axially translational motion unit.

[0040] The valve chamber housing 1 surrounds a valve chamber 10, which extends annularly around the closing element 20. The valve chamber housing 1 thus forms an outer circumferential wall, and the closing element 20 forms an inner circumferential wall of the valve chamber 10. The second chamber inlets 12 open laterally, for example radially, into the valve chamber 10 at the circumference of the valve chamber housing 1. They can be permanently connected to the valve chamber 10. In the closed position, the closing element 20 separates the valve chamber 10 from the first chamber inlet 11. When the closing element 20 assumes the release position, i.e., has lifted off the valve seat 4, the first chamber inlet 11 opens axially through the valve seat 4 into the valve chamber 10.

[0041] The valve chamber housing 1 surrounds a rear axial section of the closing element 20 and forms a closing element sliding guide 2 there, which guides the closing element 20 axially in a sliding contact. The closing element 20 and the closing element sliding guide 2 form a sealing gap in the sliding contact, through which the valve chamber 10 is sealed. The valve chamber housing 1 widens radially outwards from the closing element sliding guide 2 into the valve chamber 10 adjoining it in the closing direction X via an annular shoulder. The annular shoulder forms the stop 16 for the release position.

[0042] The valve seat 4 is formed by a bushing 3, which is inserted into a front end section of the valve chamber housing 1. The bushing 3 is immovably joined to the valve chamber housing 1, for example, by being pressed into the front end section of the valve chamber housing 1. The bushing 3 forms the circumferential wall of the first chamber access 11, so that the inner circumference of the bushing 3 determines the cross-section of the first chamber access 11. The valve seat 4 rotates continuously around the valve axis L at the rear end of the bushing 3, which faces axially towards the valve chamber 10. The closing element 20 has a closing surface 24 at its front end, which faces axially towards the bushing 3 and the first chamber access 11, with which the closing element 20 is in sealing contact with the valve seat 4 in the closed position.In advantageous embodiments, the valve seat 4 and the closing surface 24, and thus also the sealing contact, rotate continuously around the valve axis L and block any flow in the closed state.

[0043] The spring assembly 25 is arranged in the valve chamber 10 and surrounds the closing element 20. In the closing direction X, the spring assembly 25 is supported by a housing support, in this embodiment by the bushing 3, and in the releasing direction -X by a spring support 22 of the closing element 20. The spring assembly 25 is axially compressed between the housing support and the spring support 22. In this embodiment, the spring assembly 25 is a helical compression spring.

[0044] The bracket 7 encompasses the coil housing 5, so that the latter is axially held between a front leg and a rear leg of the bracket 7. The coil housing 5 surrounds the coil 35, which in turn surrounds another, inner coil housing 6. The two coil housings 5 ​​and 6 enclose the coil 35 in a fluid-tight manner. The coil 35 can be connected to a power supply via the coil terminal 36. The coil terminal 36 is formed directly on the outside of the coil housing 5.

[0045] The valve chamber housing 1 extends through the front leg of the bracket 7, which has a passage adapted in size and shape for this purpose. The valve chamber housing 1 is rigidly connected to the bracket 7 in the area of ​​the passage, for example by means of a screw connection. In the connected state, the rear leg of the bracket 7 presses the coil housings 5 ​​and 6 with a certain axial clamping force against a shoulder surface of the valve chamber housing 1 and / or the front leg of the bracket 7.

[0046] The valve housing forms an armature slide guide 9, which guides the armature 30 axially in a sliding contact. For this purpose, the valve housing includes a pressure sleeve 8 with a sleeve-shaped guide section that surrounds the armature 30 in sliding contact, thus forming the armature slide guide 9. The pressure sleeve 8 further includes a rear section that connects to the sleeve-shaped guide section in the release direction -X and closes it at its end face, so that a rear housing chamber 13 is formed at the rear of the armature 30. The pressure sleeve 8 then widens in the closing direction X beyond the armature slide guide 9 in a front joining section and surrounds a rear end section of the valve chamber housing 1 with its also sleeve-shaped joining section. In this area, the valve chamber housing 1 and the pressure sleeve 8 are joined together immovably and fluid-tight.The pressure sleeve 8 can be formed in one piece, for example from steel, especially stainless steel, by deep drawing or deep forming. It shields the coil housing 5, 6 and thus the coil 35 from the fluid, especially from potentially high fluid pressures.

[0047] The rear leg of the bracket 7 has an axial passage into which a sleeve 15 is inserted. The sleeve 15 serves to hold the pressure sleeve 8 and thus ultimately also to guide the anchor 30.

[0048] A compensation chamber 14 located on the outer circumference of the anchor 30 is connected to the anchor cavity 31 via a pressure equalization opening 33 of the anchor 30. In the exemplary embodiment, the pressure sleeve 8 surrounds the compensation chamber 14. In this embodiment, the compensation chamber 14 is bounded radially on the inside directly by the anchor 30 and radially on the outside directly by the pressure sleeve 8. In every position of the locking element 20, the compensation chamber 14 is connected to the rear housing chamber 13 via the pressure equalization opening 33 and the anchor cavity 31.

[0049] In the closed position, the closing element 20 can project axially beyond the valve chamber housing 1 in the release direction -X and, due to the stop contact, release the armature 30 from the valve chamber housing 1 in the axial direction, so that the armature 30 has no axial contact with the valve chamber housing 1 even in the closed position.

[0050] Valve V is designed for a short switching time. Switching time is defined as the time it takes for valve V to change from closed to open when the actuating force is removed. The switching time can be measured by the time it takes for the closing element 20 to move from the closed position to the open position, thus fully opening the connection cross-section and reaching its nominal size. To reduce the switching time, the closing element 20 and the armature 30 are designed as hollow bodies. An axially extending closing element cavity 21 and an axially extending armature cavity 31 extend through the closing element 20 and the armature cavity 31, respectively. The closing element cavity 21 and the armature cavity 31 extend axially as a single, continuous passage through the entire moving unit consisting of the closing element 20 and the armature 30.The closing element cavity 21 opens at a front cavity opening of the closing element 20 into the first chamber access 11 and at a rear cavity opening of the anchor 30 into the rear housing space 13, which is formed in the valve housing at the rear of the anchor 30 and into which the movement unit 20, 30 enters when moving in the release direction -X.

[0051] For a short switching time, the connection cross-section between the valve chamber 10 and the first chamber access 11, which is closed by the closing element 20 in the closed position, increases rapidly when the closing element 20 moves in the release direction -X. H denotes the length of the axial stroke that the closing element 20 travels when moving from the closed position to the release position. To achieve a rapid increase in the connection cross-section and a large connection / release cross-section with a short stroke length H in the release position, the first chamber access 11 has a large cross-section axially at the level of the sealing contact between the closing element 20 and the valve seat 4. In the exemplary embodiment, the chamber access 11 is cylindrical, and the cross-section axially at the level of the sealing contact is circular with a diameter K.It is advantageous if the diameter K is at least three times, or better yet at least four times, as large as the stroke length H.

[0052] The Fig. 4 and Fig. Figure 5 shows the closing element 20 individually in an isometric view and a longitudinal section in which the valve axis L extends. The closing element 20 is generally sleeve-shaped and has a thin wall thickness along its entire length compared to closing elements of conventional poppet valves. Its inner circumference, and consequently the closing element cavity 21, extends smoothly cylindrically in the axial direction through the closing element 20, thus having the same cross-section along its entire length. Optional chamfers at the end faces are disregarded with regard to the characterization as "cylindrical along its entire length".

[0053] The closing element 20 widens slightly around its outer circumference via a flare 23, which extends continuously around the valve axis L. As a result, the closing element 20 has a rear sleeve section with a wall thickness that is constant both circumferentially and axially, and, adjoining this in the closing direction X, a front sleeve section, also with a wall thickness that is constant both circumferentially and axially, but slightly greater than the wall thickness of the rear sleeve section. The flare 23 is formed as a radially slender annular shoulder. The flare 23 is dimensioned such that the fluid does not exert a resultant axial force on the closing element 20 when the closing element 20 is in the closed position. As can be seen particularly in the longitudinal section of the Fig. As can be seen in Figure 5, the closing surface 24 is conical and, in the closed position, projects slightly radially outwards beyond the immediate sealing contact with the valve seat 4. This slight radial projection is compensated for by the expansion 23. This is illustrated by the two dotted lines that extend the outer circumference of the rear sleeve section axially beyond the valve seat 4.

[0054] The release position of the closing element 20 can be determined by axial stop contact of the spring support 22 and / or the expansion 23 against the stop 16 of the valve housing ( Fig. 3) can be determined. The stroke length H can therefore correspond to the axial distance between the stop 16 and the spring support 22 or the expansion 23.

[0055] In the exemplary embodiment, the locking element 20, apart from the spring support 22, is cylindrical over its outer circumference and has an outer diameter D in the front sleeve section, which forms the locking surface 24. S The locking element cavity 21 is also circularly cylindrical. The locking element 20 has an inner diameter d everywhere around its inner circumference. S on. For the diameter ratio, D is advantageously used. S ≤ 2 · d S The inner diameter d S is therefore significantly greater than the wall thickness in the expanded front sleeve section of the locking element 20. In the exemplary embodiment, D applies. S / d S = 4 / 3.

[0056] Generalized to any other, but at least essentially still sleeve-like, locking elements, it is advantageously the case that the overall measured volume of the locking element 20 is advantageously at most four times the volume of the locking element cavity 21 and, even more advantageously, at most three times the volume of the locking element cavity 21. With respect to the ratio of an arbitrarily shaped locking element cavity 21 to the wall thickness, the inner diameter d SThe minimum radial width in the respective cross-section of the locking element 20 and the wall thickness are replaced by a maximum wall thickness of the surrounding shell of the locking element 20 in the same cross-section. In generalization, it is advantageous if the locking element cavity 21 has a minimum radial width over its entire length in the respective cross-section that is at least twice or at least three times as large as a maximum wall thickness of the surrounding shell in the same cross-section.

[0057] The spring support 22 is formed by several support elements that project radially outwards like wings from the outer circumference of the closing element 20. The support elements are each slender in the circumferential direction, so that the spring support 22 provided by the support elements is located in the valve chamber ( Fig. 3) opposes only a low flow resistance to the axial movement of the closing element 20. This measure also contributes to reducing the switching time. The gaps remaining circumferentially between the support elements have a greater total extent than the spring support 22. The support elements together form a resistive surface that opposes axial movements. This resistive surface is part of a virtual annular area that, viewed axially from one of the two end faces of the closing element 20, extends around the cylindrical portion of the outer circumference of the closing element 20 remaining between the support elements and is bounded radially inwards by this outer circumference of the closing element 20 and radially outwards by an envelope surrounding the support elements, preferably a circumcircle.To reduce the flow resistance generated by the spring support 22, it is advantageous if the combined area of ​​the virtual ring surface remaining free in the gaps between the support elements is at least twice or at least three times larger than the resistance area of ​​the support elements. The smaller the resistance area is in relation to the area of ​​the gaps when viewed axially, the smaller the flow resistance caused by the spring support 22.

[0058] Fig. Figure 6 shows the anchor 30 in a longitudinal section in which the valve axis L extends. The anchor 30 has a smooth cylindrical outer circumference over its entire axial length, i.e., an outer circumference with a uniform cross-section. Chamfers on the end faces are neglected here. The anchor 30 also has a smooth cylindrical inner circumference over the majority of its length, which bounds the anchor cavity 31 around its circumference. However, the anchor cavity 31 widens in a rear cavity section towards the rear cavity opening, forming a widening 32.

[0059] In the exemplary embodiment, the anchor 30 is circularly cylindrical over its outer circumference and, in the front axial section, also over its inner circumference. Let the outer diameter of the anchor 30 be denoted by D. A and the inner diameter of the cylindrical axial section of the anchor cavity 31 with d A , applies in advantageous versions DA ≤ 4 · d A or, even more advantageously, D A ≤ 3 · d A In the exemplary embodiment, the following applies to the diameter ratio D. A / d A = 2 / 1. Although the anchor 30 has a greater wall thickness than the closing element 20 in order to generate a sufficiently large actuating force via the cylindrical axial section of the anchor cavity 31, the inner diameter d A over the length of the cylindrical section of the anchor cavity 31 is still greater than the wall thickness in the same anchor section.

[0060] Generalized to any other anchor shapes that are at least essentially still sleeve-like, it is advantageous that the overall volume of the anchor 30, in advantageous embodiments, corresponds to at most five times the volume of the anchor cavity 31 and, even more advantageously, to at most four times the volume of the anchor cavity 21. With respect to the ratio of an arbitrarily shaped anchor cavity 31 to the wall thickness, the inner diameter d AThe minimum radial width in the respective cross-section of the anchor 30 and the wall thickness are replaced by the maximum wall thickness of the surrounding shell of the anchor 30 in the same cross-section. In generalization, it is advantageous if the anchor cavity 31 has a minimum radial width over its entire length in the respective cross-section that is greater than the maximum wall thickness of the surrounding shell in the same cross-section of the anchor 30. Advantageously, it is at least 50% greater.

[0061] The widening 32 in the rear section of the anchor cavity 31 is funnel-shaped. It can, for example, be trumpet-shaped or, as in the exemplary embodiment, expediently conical. In the rear cavity section, the cross-section of the anchor cavity 31 increases continuously until just before the rear cavity opening. The anchor cavity 31 thus widens continuously in a funnel shape into the rear housing space 13 ( Fig. 3) The expansion 32 facilitates the displacement of fluid from the rear housing chamber 13 into the armature cavity 31, thereby reducing the resistance that the fluid in the rear housing chamber 13 opposes to the movement of the armature 30 in the release direction -X. The expansion 32 also reduces the mass of the armature 30, thus increasing the acceleration of the moving unit consisting of the locking element 20 and the armature 30 during reversal, given a specific spring force. Advantageously, the expansion 32 extends over more than 10% or 15% of the total length of the armature 30. In the exemplary embodiment, it extends over approximately 20% of the total length of the armature 30. The armature 30 has its thinnest wall thickness immediately at the rear cavity opening, where it is less than half the wall thickness in the cylindrical section of the armature cavity 31.

[0062] Fig. Figure 7 shows an application example for valve V. In this example, valve V serves as a backup valve in a hydraulic steering system. Only two wheels of the vehicle, such as the front wheels of an automobile, are shown, connected via a steering linkage. The steering movements made by the driver at a steering device of the vehicle, such as a steering wheel, are transmitted to the axles of the two wheels via the linkage. A double-acting piston-cylinder assembly is arranged in the transmission path of the steering linkage. The piston-cylinder assembly comprises a cylinder 40 in which a piston 41 is translationally movable back and forth. The piston 41 separates a first, in Fig. 7 left cylinder space from a second one, in Fig.7. Right cylinder chamber. The two cylinder chambers are each connected via a port to a hydraulic pump 42, which is driven by a motor 43. The two cylinder chambers can be selectively supplied with hydraulic fluid by means of the pump 42 in order to apply hydraulic pressure to the piston 41 in accordance with the steering movements and thereby assist the steering movements.

[0063] Valve V serves to connect the two cylinder chambers in certain malfunctions, such as a complete power failure, thus creating a short circuit between the cylinder chambers. To fulfill this safety function, valve V is hydraulically connected in parallel to pump 42. It is permanently connected to the first cylinder chamber via its first chamber inlet 11 and to the second cylinder chamber via its second chamber inlets 12. Under normal operating conditions, valve V is in the closed position, in which the closing element 20 assumes the closed position and separates chamber inlet 11 from chamber inlets 12, so that there is no connection between the two cylinder chambers of the piston-cylinder assembly via valve V. In the event of a power failure, however, the actuating force generated by the coil 35 and the armature 30 ceases, and the closing element 20 moves abruptly into the release position under the influence of the spring force, which is then the only force acting.In the release position, the first chamber inlet 11 is connected to the second chamber inlets 12, allowing the pressure in the two cylinder chambers of the piston-cylinder assembly to equalize via this connection. Although the hydraulic power steering is disabled, it cannot then obstruct purely manual steering movements. Reference symbol: 1 Valve chamber housing 2 Locking element sliding guide 3 sockets 4 valve seat 5 coil housings, outer structure 6 coil housings, internal structure 7 spool housings, brackets 8 Pressure sleeve 9 Anchor slide guide 10 valve chamber 11 Chamber access 12 Chamber access 13 Rear Case Compartment 14 Compensation area 15 sleeve 16 attacks 20 locking elements 21 Locking element cavity 22 Support element 23 external dilation 24 closing area 25 Spring assembly 30 anchors 31 Anchor cavity 32 Expansion 33 Compensation opening 34 - 35 coil 36 coil connection 40 cylinders 41 pistons 42 Pump 43 Pump drive D A Outer diameter d A Inner diameter D S Outer diameter d S Inner diameter H Stroke length K diameter at the valve seat L Valve shaft X Closing direction -X Release direction

Claims

Electromagnetic poppet valve comprising: 1.1 a valve body (1-15) with a valve chamber (10) into which a first chamber inlet (11) and a second chamber inlet (12) for a fluid open, 1.2 a valve seat (4) through which the first chamber inlet (11) opens into the valve chamber (10) and which rotates about a valve axis (L), 1.3 a closing element (20) which is movable back and forth in an axial direction (±X) in a closing direction (X) up to a closing position in which it is in sealing contact with the valve seat (4) and separates the first chamber inlet (11) from the second chamber inlet (12), and in a releasing direction (-X) up to a releasing position in which it releases the valve seat (4), and 1.4 an electrical coil (35) and an armature (30) movable back and forth in the axial direction (±X) for generating an actuating force which is applied in the axial direction (±X) to the The locking element (20) acts,1.5 wherein the closing element (20) has a closing element cavity (21) extending through the closing element (20) from a front cavity opening axially facing the first chamber access (11) to a rear of the closing element (10) axially away from the first chamber access (11), and / or 1.6 wherein the anchor (30) has an anchor cavity (31) extending through the anchor (30) from a front of the anchor (20) axially facing the first chamber access (11) to a rear cavity opening at a rear of the anchor (20) axially away from the first chamber access (11), characterized in that 1.7 the seat valve comprises a spring device (25) for generating a spring force acting on the closing element (20) and the actuating force, wherein 1.8 the locking element (20) has a spring support (22) consisting of several support elements projecting locally outwards on the outer circumference of the locking element (20), on which the spring device (25) is axially supported. Electromagnetic valve according to the preceding claim, wherein a uniform cavity (21, 31) extends axially through the closing element (20) and the armature (30), comprising the closing element cavity (21) and the armature cavity (31), Electromagnetic valve according to the preceding claim, wherein the uniform cavity (21, 31) opens at the front cavity opening of the closing element (20) into the first chamber access (11) and at a rear cavity opening into a rear housing space (13), so that the uniform cavity (21, 31) connects the first chamber access (11) with the rear housing space (13). Electromagnetic valve according to one of the preceding claims, wherein the closing element (20) has a total volume measured overall and this total volume corresponds to at most 4 times or at most 3 times the volume of the closing element cavity (21). Electromagnetic valve according to one of the preceding claims, wherein the armature (30) has a total volume measured overall and this total volume corresponds to at most 5 times or at most 4 times the volume of the armature cavity (31). Electromagnetic valve according to one of the preceding claims, wherein the closing element (20) and the armature (30) are part of an axially translational motion unit (20, 30) which has a uniform cavity (21, 31) comprising the closing element cavity (21) and / or the armature cavity (31). Electromagnetic valve according to the preceding claim, wherein the movement unit (20, 30) has a total volume measured overall and the uniform cavity (21, 31) within the total volume, and the total volume is at most 5 times or at most 4 times the volume of the uniform cavity (21, 31). Electromagnetic valve according to one of the preceding claims, wherein the armature cavity (31) widens radially, for example conically, in a rear cavity section (32) towards the rear cavity opening. Electromagnetic valve according to one of the preceding claims, wherein the first chamber access (11) has a flowable cross-sectional area axially at the level of the valve seat (4) which corresponds in size to a circular area with diameter K, and the closing element (20) executes a stroke of length H when moving from the closed position to the release position, wherein: K ≥ 3 • H or K ≥ 4 • H . Electromagnetic valve according to one of the preceding claims, wherein the closing element (20) and the armature (30) are part of an axial translational movement unit (20, 30) and are coupled in the movement unit (20, 30) by an axial stop contact which acts in the closing direction (X) and the release direction (-X). Electromagnetic valve according to one of the preceding claims, wherein the actuating force in the closing direction (X) and the spring force in the releasing direction (-X) act on the closing element (20). Electromagnetic valve according to one of the preceding claims, wherein the valve housing (1-15) forms an axial closing element sliding guide (2) for the closing element (20) and is preferably sealed via the closing element sliding guide (2). Electromagnetic valve according to one of the preceding claims, wherein the valve housing (1-15) forms an axial armature sliding guide (9) for the armature (30). Electromagnetic valve according to one of the preceding claims, wherein the valve housing (1-15) has a valve chamber housing (1) with a jacket section that surrounds the valve chamber (10) and the valve seat (4) and has the second chamber access (12) on a circumference, wherein the valve seat (4) is preferably offset in axial direction (±X) to the second chamber access (12) by less than a maximum axial width of the second chamber access (12). Hydraulic system for assisting the steering of a vehicle, wherein the hydraulic system has a safety valve (V) designed as an electromagnetic valve according to one of the preceding claims.

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