Solenoid valve, especially for slip-controlled motor vehicle braking systems

Abstract

Electromagnetic valve, in particular for slip-controlled motor vehicle braking systems, comprising a first and a second valve closing element (1; 2) arranged in a valve housing (3), which are coaxially arranged in the valve housing (3) and are capable of opening or closing a first and a second valve passage (13; 15), respectively, comprising a magnetic armature (4) which forms a self-contained assembly with the first valve closing element (1) and which can be applied to the second valve closing element (2) under the action of a return spring (14), comprising a magnetic core (20) in the valve housing (3) on which a spring end of the return spring (14) facing away from the assembly is supported, comprising a pressure medium inlet (8) and a pressure medium outlet (9) opening into the valve housing (3),wherein the first valve closing element (1) is able to open or close the first valve passage (13) located in the second valve closing element (2) depending on the electromagnetic excitation of a valve coil, the cross-sectional area of ​​which is smaller than the second valve passage (15) to be opened by the second valve closing element (2) in the valve housing (3), wherein the second valve closing element (2) is designed in an annular disk shape and has several guide webs (6) distributed around its circumference on its end face facing the first valve closing element (1), which extend axially between the first valve closing element (1) and the valve housing (3) along a region of the magnetic armature (4) that receives the first valve closing element (1), characterized in that each guide web (6) is provided with a radial projection (5) at its end facing away from the second valve closing element (2),a spring (12) acting on the second valve closing element (2) in the valve opening direction is supported on it, the spring (12) resting with its end facing away from the projection (5) on a step (25) of the valve housing (3).

Description

[0001] The invention relates to an electromagnetic valve, in particular for slip-controlled motor vehicle brake systems, according to the preamble of patent claim 1.

[0002] An electromagnetic valve of the type specified is already known from DE 10 2005 014 100 A1, comprising a first and a second valve closing body arranged in a valve housing, which, in a coaxial arrangement in the valve housing, can open or close a first and a second valve passage. The second valve closing body is arranged below the first valve closing body in a guide sleeve that is fixed within the valve housing. A spring is clamped between the second valve closing body and a stop arranged on the guide sleeve, which spring urges the second valve closing body in the direction of the first valve closing body. The series arrangement of the two valve closing bodies leads to an undesirably large installation height with corresponding material and weight expenditure, as well as to unfavorable conditions with regard to evacuating and filling the valve housing with brake fluid.

[0003] From DE 10 2005 058 526 A1 a two-stage electromagnetic valve is known which comprises a first and a second valve closing body arranged in a valve housing, which in a coaxial arrangement in the valve housing can open or close a first and a second valve passage, wherein the first valve passage is smaller in cross section than the second valve passage, wherein the second valve closing body is designed in the shape of an annular disk and has on its end face facing the first valve closing body a plurality of guide webs distributed over the circumference, which extend axially between the first valve closing body and the valve housing along a region of the magnet armature receiving the first valve closing body.

[0004] The object of the present invention is to design a solenoid valve of the type specified using the simplest, most functional means possible, in a cost-effective and compact manner, and to improve it in such a way that the aforementioned disadvantages do not occur.

[0005] This object is achieved according to the invention with an electromagnetic valve according to the features of patent claim 1.

[0006] Further features, advantages and possible applications of the invention will become apparent from the following description of embodiments.

[0007] They show: Fig. 1 is an overall view of an electromagnetic valve in longitudinal section, with a direct reception and guidance of the first valve closing body in the second valve closing body, Fig. 2 is an enlarged perspective view showing the details of the second valve closing body according to the invention, Fig. 3 a modification of the Fig. 1 known electromagnetic valve, the first valve closing body of which is telescopically accommodated in the magnet armature.

[0008] The Fig. Figure 1 shows, in a significantly enlarged view, a longitudinal section of an electromagnetic valve comprising a multi-part valve housing 3 with a thin-walled lower housing area constructed using a deep-drawing process. The valve housing 3 has a retaining collar manufactured by non-cutting forming and fixed in a solid central housing section 21 by means of caulking. Adjoining the solid housing section 21, manufactured as a cold-formed part, is a thin-walled sleeve 22, which is closed by a plug 20. The plug 20 also consists of a cost-effective and sufficiently precisely manufactured cold-formed part, which is laser-welded to the sleeve 22 on the outer circumference. Located beneath the plug 20 is a magnet armature 4, which is also very cost-effectively manufactured from a round or polygonal profile by cold forming or extrusion.In the valve's basic position, the magnet armature 4, under the action of a return spring 14, closes a first valve passage 13 arranged in a second valve closing body 2 with the first valve closing body 1 fastened in the tappet-shaped magnet armature extension 26. The second valve closing body 2 is designed as a particularly flat, annular disc-shaped valve piston, which is acted upon by the action of a spring 12 lifting the second valve closing body 2 from the first valve seat 16. The spring 12 is advantageously located outside the flow path connecting the pressure medium inlet channel 8 to the pressure medium outlet channel 9.

[0009] As a result of the action of the return spring 14 on the first valve closing body 1, in the basic valve position shown in the illustration, the second valve closing body 2 closes a second valve passage 15 provided in the lower end of the valve housing 3 in the second valve seat 23, the passage cross-section of which can be released depending on the hydraulic differential pressure and is considerably larger than the electromagnetically releaseable opening cross-section at the first valve passage 13.

[0010] A pressure medium inlet channel 8 opens laterally into the deep-drawn valve housing 3 at the level of the first valve passage 13. Below the second valve closing body 2 is the second valve passage 15 arranged in the pressure medium outlet channel 9. The pressure medium inlet channel 8, shown as a horizontal channel in the valve housing 3, continues into the interior of the valve closing body 2 via several large-area through openings 7 in the second valve closing body 2, so that pressure medium on the inlet side, after passing through a ring filter 24, reaches the second valve closing body 2 and the first valve closing body 1 arranged therein via the shortest route.

[0011] For unhindered evacuation and hydraulic filling of the valve housing 3, several rectangular through-openings 7 are provided between the guide webs 6, which extend over the entire height of the guide webs 6 for large-volume flow. Furthermore, the large-volume through-openings 7 ensure ideal conditions for the hydraulic connection of the pressure medium inlet channel 8 to the pressure medium outlet channel 9 when the first valve closing body 1 is electromagnetically lifted from the first valve seat 16, so that the valve flow is optimal under all operating conditions.

[0012] The second valve passage 15 is provided in a disc-shaped valve seat 23 for mechanical relief of the valve housing 3, which is held on the inner wall of the valve housing 3 by means of a press fit.

[0013] In the present exemplary embodiment, the invention provides a total of three through openings 7 distributed evenly over the circumference of the second valve closing body 2 for the purpose of flow-optimized representation, for which purpose the second valve closing body 2 has three guide webs 6 distributed evenly over the circumference on its end face facing the first valve closing body 1, so that a generously dimensioned through opening 7 can be formed at a distance between two guide webs 6, which extend axially analogously to the guide webs 6 between the first valve closing body 1 and the valve housing 3 along a region of the magnet armature 4 receiving the first valve closing body 1.

[0014] In addition, each guide web 6 is provided with a radial projection 5 at its end facing away from the second valve closing body 2, on which a spring 12 acting on the second valve closing body 2 in the valve opening direction is advantageously supported, wherein the spring 12 is simultaneously designed with its end facing away from the projection 5 in a space-optimized manner either according to the Fig. 1 at a step 25 of the deep-drawn, pot-shaped valve housing 3 or according to the Fig. 3 rests directly on a radially inwardly projecting retaining collar 27.

[0015] As can be seen from the Fig. 1 and Fig. 3, the area of ​​the magnet armature 4 receiving the first valve closing body 1 is received in sections along its outer surface between the guide webs 6 and guided in the axial direction onto the first valve passage 13 arranged in the second valve closing body 2, so that during a relative movement of the parts only minimal friction prevails between the magnet armature 4 and the guide webs 6.

[0016] The second valve closing body 2 is guided over a small area and thus also with low friction via the radially outwardly directed projection 5 along the inner wall of the valve housing 3, wherein each guide web 6, for the purpose of precise alignment of the second valve closing body 2 in the valve housing 3, has, in addition to each projection 5, a further small-area contact section 10 which, at an axial distance from each projection 5, contacts the inner circumference of the valve housing 3 in sections in the manner of a skid.

[0017] The Fig. 2 shows an enlarged perspective view illustrating the details of the second valve closing body 2 according to the invention, according to which the second valve closing body 2 has, in a one-piece connection, the three guide webs 6 evenly distributed over the circumference of the plate-shaped valve closing body 2. All of the illustrated details of the valve closing body 2 are manufactured from a wear-resistant plastic, in particular from a thermoplastic (e.g., PEEK), in a single operation and are particularly small and lightweight. The valve closing body 2, in conjunction with the guide webs 6, the first valve seat 16, and the valve passage 13 provided in the valve seat 16, can thus be manufactured cost-effectively as an injection-molded part with extremely low material expenditure.

[0018] The Fig. 3 shows a further embodiment of the Fig. 1 and already shown in the basic details, additionally a driver sleeve 11 which accommodates the first valve closing body 1 axially movable relative to the magnet armature 4 and which is fixed to the tappet-shaped magnet armature extension 26, so that the magnet armature extension 26 is not as in the Fig. 1 directly, but is received and guided via the driver sleeve 11 between the guide webs 6 in the second valve closing body 2.

[0019] In the Fig. 3, the magnet armature 4 is thus designed to be telescopically movable relative to the first valve closing body 1, so that an electromagnetic actuation of the magnet armature 4 is advantageously ensured, which is not impaired by the hydraulic closing force which acts on the first valve closing body 1 opposite to the opening stroke of the magnet armature 4.

[0020] In the simplest design, the first valve closing body 1 is therefore coupled to the magnet armature 4 via the driver sleeve 11 with a certain amount of play.

[0021] The driver sleeve 11 consists of a thin sheet produced by the deep-drawing process, which is connected to the magnet armature 4 in a force-locking and / or form-locking manner and whose horizontally projecting edge 19 on the circumference of the magnet armature extension 26 forms the end.

[0022] In order to be able to lift the first valve closing body 1 from the first valve seat after an initial partial stroke of the magnet armature 4, the driver sleeve 11 is located on the magnet armature 4, which holds the first valve closing body 1 on the magnet armature 4 so that it can move relatively freely within certain limits. The driver sleeve 11 has an annular disk-shaped stop shoulder 18, through the opening of which the first valve closing body 1 extends with its tappet section in the direction of the first valve seat 16 in the second valve closing body 2. A bridgeable distance is provided between the stop shoulder 18 and a stop 17 provided on the tappet section in order to ensure relative movement between the magnet armature 4 and the first valve closing body 1. As a result, at the beginning of the magnet armature stroke, the first valve closing body 1 initially keeps the first passage 13 in the second valve closing body 2 closed.

[0023] The following explains the functionality of the solenoid valve using the example of Fig. 3 are described: In the illustrated, electromagnetically non-excited valve position, both valve closing bodies 1, 2 assume their valve closing positions due to the closing force of the return spring 14, whose spring force is larger than the force of the opposing spring 12.

[0024] Provided that equal hydraulic pressures prevail in the pressure medium inlet and outlet channels 8, 9, the magnet armature 4, when electromagnetically excited, travels a stroke until it rests against the magnetic core (plug 20), which stroke corresponds to the maximum stroke of the second valve closing body 2. Since the effect of the return spring 14 on the valve closing bodies 1, 2 is canceled out during electromagnetic excitation, both adjacent valve closing bodies 1, 2 move synchronously with the magnet armature movement due to the effect of the spring 12, so that the maximum cross-section at the valve passage is released immediately after electromagnetic excitation.

[0025] However, if the pressure in the pressure medium inlet channel 8 is greater than the hydraulic pressure in the pressure medium outlet channel 9, the effect of the spring 12 on the second valve closing body 2 is reduced by the amount of force resulting from the hydraulic loading of the second valve closing body 2. Accordingly, the reaction of the spring 12 on the first valve closing body 1, which is loaded in the closing direction in addition to the force of the return spring 14 under the effect of the hydraulic pressure difference, is also reduced or eliminated.

[0026] If, under the conditions described, an electromagnetically initiated stroke movement of the solenoid armature 4 now occurs, the solenoid armature 4 initially travels a partial stroke under compression of the return spring 14 until the first valve closing body 1 is driven by the drive sleeve 11. During this partial stroke, the first, hydraulically unpressure-balanced valve closing body 1 remains in the closed position shown on the second valve closing body 2 under the effect of the hydraulic pressure.At the moment when, as a result of the relative movement of the magnet armature 4 relative to the first valve closing body 1, the stop shoulder 18 of the driver sleeve 11 touches the stop 17 formed on the first valve closing body 1, the distance of the magnet armature 4 from the magnet core (plug 20) is already reduced to a minimum by the partial stroke, so that advantageously only a small electromagnetic excitation is required in order to bridge the remaining minimal air gap between the magnet core and the magnet armature 4 in order to lift the first valve closing body 1 from the first valve passage 13.

[0027] Thus, the first valve closing body 1 is lifted above the driver sleeve 11 only shortly before the magnet armature 4 reaches the magnet core (plug 20), whereby the first valve closing body 1 moves away from the second valve closing body 2 and releases the aperture-shaped first valve passage 13. This creates the prerequisite, in a relatively simple manner, for the second valve closing body 2, supported by the spring 12, to also open the large, throttle-free cross-section in the second valve passage 15. List of reference symbols 1 valve closing body 2 valve closing bodies 3 valve housings 4 magnet armatures 5 lead 6 Guide bar 7 Passage opening 8 Pressure medium inlet channel 9 Pressure medium outlet channel 10 Contact section 11 Driving sleeve 12 springs 13 Valve passage 14 Return spring 15 valve passage 16 Valve seat 17 stop 18 Stop shoulder 19 Edge 20 plugs 21 Housing section 22 sleeve 23 Valve seat 24 ring filters 25th level 26 Magnet armature extension 27 retaining collars

Claims

[1] Electromagnetic valve, in particular for slip-controlled motor vehicle braking systems, with a first and a second valve closing body (1; 2) arranged in a valve housing (3), which, in a coaxial arrangement in the valve housing (3), can open or close a first and a second valve passage (13; 15), with a magnet armature (4) which, with the first valve closing body (1), forms an independently manageable assembly which, under the action of a return spring (14), can be applied to the second valve closing body (2), with a magnet core (20) in the valve housing (3), on which a spring end of the return spring (14) facing away from the assembly is supported, with a pressure medium inlet (8) opening into the valve housing (3) and a pressure medium outlet (9),wherein the first valve closing body (1) is capable of opening or closing the first valve passage (13) located in the second valve closing body (2) depending on the electromagnetic excitation of a valve coil, the passage cross-section of which is smaller than the second valve passage (15) to be opened by the second valve closing body (2) in the valve housing (3), wherein the second valve closing body (2) is designed in the shape of an annular disc and has, on its end face facing the first valve closing body (1), a plurality of guide webs (6) distributed over the circumference, which extend axially between the first valve closing body (1) and the valve housing (3) along a region of the magnet armature (4) receiving the first valve closing body (1), characterized bythat each guide web (6) is provided at its end facing away from the second valve closing body (2) with a radial projection (5) on which a spring (12) acting on the second valve closing body (2) in the valve opening direction is supported, the spring (12) resting with its end facing away from the projection (5) on a step (25) of the valve housing (3). [2] Solenoid valve according to claim 1, characterized by that the second valve closing body (2) is guided along the inner wall of the valve housing (3) via the radially outwardly directed projection (5). [3] Solenoid valve according to claim 2, characterized by that for unhindered evacuation and hydraulic filling of the valve housing (3) between the guide webs (6) a plurality of rectangular passage openings (7) are provided, which extend over the entire height of the guide webs (6) for large-volume flow. [4] Solenoid valve according to claim 2, characterized by that each guide web (6) has, in addition to each projection (5), a further contact section (10) for the purpose of precisely guiding the second valve closing body (2) in the valve housing (3), for which purpose each guide web (6) contacts the inner circumference of the valve housing (3) in sections in the manner of a skid at an axial distance from each projection (5). [5] Solenoid valve according to claim 4, characterized by that the second valve closing body (2) is made of a plastic, in particular of a thermoplastic, in one-piece connection with the guide webs (6). [6] Solenoid valve according to one of the preceding claims, characterized by that the second valve closing body (2) is manufactured as an injection-molded part.

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