Solenoid valve

Abstract

An electromagnetic valve, in particular for a motor vehicle air suspension system, comprising a valve closing element (2) arranged in a valve housing (17), which is capable of opening or closing a valve passage (7) in a valve seat (11) in the valve housing (17), a magnetic armature (1) which forms a self-contained, operable assembly with the valve closing element (2) which is capable of closing the valve passage (7) under the action of a return spring (10), a magnetic core (18) fixed in the valve housing (17) on which a spring end of the return spring (10) facing away from the assembly is supported, and a pressure medium inlet (19) and a pressure medium outlet (20) opening into the valve housing (17), which are connected to each other via the valve closing element (2) lifted from the valve seat (11) when a valve coil is electromagnetically energized.wherein the magnetic armature (1) and the valve closing element (2), designed as a piston, are arranged to be relatively movable relative to each other in the stroke direction and are made of different materials, wherein the valve closing element (2) consists of a non-metallic material which is acted upon by a compression spring (13) to open the valve, wherein the magnetic armature (1) has a driver (3) which engages with the valve closing element (2) after a defined magnetic armature stroke in the direction of the magnetic core (18), characterized in that the driver (3) consists of a driver sleeve fixed to the magnetic armature (1) which projects from the magnetic armature (1) in the direction of the valve seat (11), so that the valve closing element (2) with its piston collar (12) is positively received in the section of the driver sleeve projecting from the magnetic armature (1) for this purpose a collar (4) directed radially inwards is provided on the driver sleeve against which the piston collar (12) can be applied,wherein the valve closing element (2) with its piston area facing away from the piston collar (12) and protruding from the drive sleeve is acted upon by a compression spring (13) which is supported at its end facing away from the valve closing element (2) on the valve seat (11), wherein the compression spring (13) positioned between the valve closing element (2) and the valve seat (11) has a spring force which is dimensioned as smaller than the closing force of the return spring (10), wherein a plastic ring (8) is fixed on the circumference of the valve closing element (2) against which the end of the compression spring (13) facing away from the valve seat (11) is supported.

Description

[0001] The invention relates to an electromagnetic valve, in particular for a motor vehicle air suspension system, according to the preamble of claim 1.

[0002] An electromagnetic valve of the type described is already known from DE 10 2012 206 282 A1, comprising a valve closing element arranged in a valve housing, which is capable of opening or closing a valve passage in the valve housing. The valve closing element, together with a magnetic armature, forms a self-contained, operable assembly which, in the valve's home position, is capable of closing the valve passage under the action of a return spring. The valve housing is closed on the side facing away from the valve closing element by a magnetic core, against which a spring end of the return spring, facing away from the assembly, is supported. A pressure medium inlet and a pressure medium outlet open into the cartridge-shaped valve housing and are connected to each other via the valve closing element, which is lifted from the valve passage, when a valve coil is electromagnetically energized.

[0003] However, due to its design, the presented solenoid valve is only suitable for a small flow rate and a small valve stroke.

[0004] From DE 195 29 724 A1 a two-stage solenoid valve is known, comprising a valve tappet which closes a first valve passage on a piston-shaped valve closing element, wherein the valve closing element closes a valve seat in the valve housing, wherein the valve closing element is acted upon by a compression spring to open.

[0005] Furthermore, a two-stage solenoid valve is also known from DE 195 30 899 A1, comprising a valve closing ball which closes a first valve passage on a piston-shaped valve closing element, wherein the valve closing element closes a valve seat in the valve housing, wherein the valve closing element is arranged in a sleeve which is attached to the magnetic armature under the influence of a compression spring.

[0006] The object of the present invention is to design an electromagnetic valve of the specified type in a cost-effective and compact manner using the simplest possible functional means and to improve it in such a way that large volume flows can be switched with the lowest possible energy requirement.

[0007] This problem is solved according to the invention with an electromagnetic valve according to the features of claim 1.

[0008] Further features and advantages will become apparent from the description of several exemplary embodiments below.

[0009] They show: Fig. Figures 1 to 5 each show a longitudinal section of a first advantageous embodiment of the non-inventive solenoid valve in various switching positions, the piston-shaped valve closing element of which is partially received in a driver, Fig. 6 and Fig. 7 each the solenoid valve after Fig. 1-5 with modifications in the area of ​​the valve closing body, which is provided with a guide pin and immerses into a guide bore of the magnetic armature.

[0010] The Fig. Figure 1 shows a longitudinal section of a highly magnified solenoid valve with a multi-part valve housing 17, the lower housing area 21 of which is deep-drawn and fixed in a solid central housing section 22. A thin-walled, non-conductive sleeve 23, preferably made of stainless steel, is attached to the solid, magnetic flux-conducting steel housing section 22, which is manufactured as a cold-forged part. The sleeve 23 is sealed by a plug-shaped magnetic core 18. The magnetic core 18 is also a cost-effective and sufficiently precisely manufactured cold-forged part, which is laser-welded to the outer circumference of the sleeve 23.

[0011] The solenoid valve, designed as a valve cartridge, is fastened in the area of ​​the solid steel housing section 22 by means of an external riving in a light metal valve block 15, preferably made of extruded material, whereby the light metal is plastically displaced against a shoulder 16 of the steel housing section 22, which is supported on a bore step of the valve block 15 facing away from the shoulder 16.

[0012] Below the magnetic core 18 is a magnetic armature 1 guided in the sleeve 23, which is also very cost-effectively manufactured from a round or polygonal profile by cold forging or extrusion. Under the action of a return spring 10, the magnetic armature 1, in the valve's initial position, closes a valve passage 7 provided in the valve seat 11 of the cartridge-shaped valve housing 17, together with the valve closing element 2, which is movably attached to the tapered extension of the magnetic armature. Fig. 3, Fig. 4 is clearly visible. The valve closing element 2 is designed as a valve piston, which is acted upon by a compression spring 13 that lifts the valve closing element 2 from the valve seat 11.

[0013] A pressure medium inlet 19 opens laterally into the valve housing 17 at the level of the valve closing element 2. The pressure medium outlet 20 is located below the valve seat 11.

[0014] In order to enable large flow cross-sections in combination with a large valve stroke, the invention provides that the magnetic armature 1 and the piston-shaped valve closing element 2 are connected to each other in a relatively movable manner in the stroke direction according to the telescopic principle, for which purpose a driver 3 is formed on the magnetic armature 1, so that when electromagnetically actuated, after a defined armature stroke in the direction of the magnetic core 18, during which the driver 3 simultaneously travels an idle stroke L until contacting the valve closing element 2, the valve closing element 2 is lifted off from the valve seat 11 with the help of the driver 3 and supported by a compression spring 13.

[0015] As can be seen from all the figures, the magnetic armature 1 with the driver 3 and the valve closing body 2 forms an independently manageable and testable assembly, so that the driver 3, when the magnetic armature stroke is completed in the direction of the magnetic core 18, engages mechanically with the valve closing body 2 in a simple way after bridging the so-called idle stroke L.

[0016] Advantageously, the driver 3 consists of a driver sleeve fixed to the magnetic armature 1, which projects from the magnetic armature 1 towards the valve seat 11, so that the valve closing element 2 with its easily manufactured piston collar 12 is functionally received in the protruding section of the driver sleeve. A radially inwardly directed collar 4 on the driver sleeve provides a positive locking connection, against which the piston collar 12 can be applied after bridging the idle stroke L, so that the valve closing element 2 can be lifted from the valve seat 11 by the driver 3.

[0017] In order to ensure that the valve passage 7 is fully opened after the electromagnetic actuation of the magnetic armature 1, the invention provides for all embodiments that the valve closing element 2, with its piston area facing away from the piston collar 12 and protruding from the driver sleeve, is permanently acted upon by the compression spring 13 in the valve opening direction, the spring of which is supported with its end facing away from the valve closing element 2 on the valve seat 11.

[0018] For the purpose of a flawless, noiseless valve closure, the invention further provides that the piston surface of the valve closing element 2 facing the valve seat 11 receives an elastically deformable sealing element 9, which, through the action of the return spring 10 on the magnetic armature 1, bears against the valve seat 11 in the electromagnetically non-excited valve closing position, as can be seen from the Fig. 1, 5 to 7 can be identified. The Fig. Figures 1, 5 to 7 thus show the solenoid valve in the electromagnetically unexcited, closed valve basic position, in which the piston surface of the valve closing element 2 facing the magnetic armature 1 rests against the end face of the magnetic armature 1 under the action of the return spring 10.

[0019] In the Fig. 2 and Fig. In each case, the solenoid valve is in a position where, after the electromagnetic actuation of the magnetic armature 1 has bridged a defined armature stroke, the sleeve-shaped driver 3 with its collar 4 contacts the piston collar 12 of the valve closing element 2. With further armature stroke, this causes the valve closing element 2 to lift from the valve seat 11 and follow the stroke movement of the magnetic armature 1 synchronously. It should be noted that initially, the inlet pressure P1 in the pressure medium inlet 19 also acts on the upper piston surface of the valve closing element 2 in the valve closing direction, until the pressure of the inlet pressure P1 is reduced towards the pressure medium outlet 20 by the opening of the valve passage 7 forced by the driver 3.

[0020] First those from the Fig. The partial opening of the valve passage 7, as shown in Figure 3, allows pressure equalization between the pressure medium inlet 19 and the pressure medium outlet 20, whereby, as a result of the pressure equalization, the valve closing element 2 is relieved of pressure to such an extent that, in a manner from the Fig. 4. As can be seen, the spring force of the compression spring 13 positioned between the valve closing body 2 and the valve seat 11 is large enough to enable the complete opening stroke of the valve closing body 2 when the magnetic armature 1 is already in contact with the magnetic core 18, for which purpose the valve closing body 2 with its upper piston surface finally contacts the lower piston surface of the magnetic armature 1 under the action of the compression spring 13.

[0021] Basically, the compression spring 13 is designed such that it has a sufficient spring force to fully open the valve, but this force is smaller than the closing force of the return spring 10 to ensure the safe closure of the valve passage 7 in the valve's basic position.

[0022] To adjust the idle stroke L, in which the valve closing element 2 is initially not driven by the driver 3 attached to the magnetic armature 1 upon electromagnetic excitation according to the definition, the driver 3 engages with the outer surface of the magnetic armature 1 by means of a sliding press fit, so that the piston collar 12 only moves after bridging the adjustable idle stroke L (vertical distance between the collar 4 and the piston collar 12) and reaching a defined magnetic armature stroke (see Fig. 2) the collar 4 is contacted to engage the valve closing element 2. This free stroke L initially only brings the magnetic armature 1 close to the magnetic core 18, without requiring a high magnetic actuation force to open the valve, so that after the air gap between the magnetic armature 1 and the magnetic core 18 is reduced, a sufficiently large magnetic force is present to engage and thus lift the valve closing element 2 from the valve seat 11 by the driver 3.

[0023] In addition to the previous ones, from the Fig. 1-5 known constructive designs are according to the Fig. 6 and Fig. 7 the piston surface of the valve closing body 2 facing the magnetic armature 1 is provided with a guide pin 14 which is slidably received in a guide bore 5 of the magnetic armature 1 for precise alignment and guidance in the magnetic armature 1.

[0024] The Fig. Figure 6 shows, according to the invention, a plastic ring 8 fixed on the circumference of the valve closing body 2 in the manner of a clip connection, on which, in contrast to embodiments 1 to 5, 7, the end of the compression spring 13 facing away from the valve seat 11 is supported.

[0025] Finally, the solenoid valve differs according to the Fig. 7 of the preceding embodiments by a stop ring 6 arranged between the magnetic armature 1 and the valve closing body 2, which is fixed to the guide pin 14 of the valve closing body 2 in such a way that after bridging the idle stroke L (vertical distance between the collar 4 and the stop ring 6) to lift the valve closing body 2 from the valve seat 11 the driver 3 engages with the stop ring 6.

[0026] Preferably, in all embodiments, the valve closing element 2 consists either of austenitic stainless steel, manufactured by machining a stainless steel blank on an automatic lathe, or of a plastic, in particular a thermoplastic, for which an injection molding process is used for cost-effective production. Likewise, the stop ring 6 is preferably made of a plastic, in particular a thermoplastic, so that both parts are combined into a lightweight and noise-reducing unit. When the proposed solenoid valve is used in a pneumatic system, the use of stainless steel instead of plastic ensures permanent corrosion protection, which must be taken into account if the air is not sufficiently dried due to humidity. Reference symbol list 1 magnetic armature 2 valve closing elements 3 drivers 4 collars 5 guide holes 6 Stop ring 7 Valve passage 8 plastic rings 9 Sealing element 10 Return spring 11 Valve seat 12 piston collar 13 Compression spring 14 guide pins 15 Valve block 16 Shoulder 17 Valve housings 18 magnetic cores 19 Pressure medium inlet 20 Pressure medium outlet 21 Housing area 22 Housing area 23 Sleeve

Claims

[1] Electromagnetic valve, in particular for a motor vehicle air spring system, with a valve closing body (2) arranged in a valve housing (17), which is capable of opening or closing a valve passage (7) in a valve seat (11) in the valve housing (17), with a magnet armature (1) which, together with the valve closing body (2), forms an independently manageable assembly which, under the action of a return spring (10), is capable of closing the valve passage (7), with a magnet core (18) fixed in the valve housing (17), on which a spring end of the return spring (10) facing away from the assembly is supported, and with a pressure medium inlet (19) and a pressure medium outlet (20) opening into the valve housing (17), which are connected to one another via the valve closing body (2) lifted from the valve seat (11) upon electromagnetic excitation of a valve coil,wherein the magnet armature (1) and the valve closing body (2) designed as a piston are arranged to be movable relative to one another in the stroke direction and are made of different materials, wherein the valve closing body (2) consists of a non-metallic material which is acted upon by a compression spring (13) to open the valve, wherein the magnet armature (1) has a driver (3) which engages with the valve closing body (2) after a defined magnet armature stroke in the direction of the magnet core (18), , characterized bythat the driver (3) consists of a driver sleeve fixed to the magnet armature (1), which projects from the magnet armature (1) in the direction of the valve seat (11), so that the valve closing body (2) with its piston collar (12) is received in a form-fitting manner in the section of the driver sleeve projecting from the magnet armature (1), for which purpose a collar (4) directed radially inwards is provided on the driver sleeve, against which the piston collar (12) can be placed, wherein the valve closing body (2) with its piston region facing away from the piston collar (12) and protruding from the driver sleeve is acted upon by a compression spring (13), which is supported with its end facing away from the valve closing body (2) on the valve seat (11), wherein the compression spring (13) positioned between the valve closing body (2) and the valve seat (11) has a spring force which is smaller than the closing force of the return spring (10), wherein on the circumference of the valve closing body (2) a plastic ring (8) is fixed,on which the end of the compression spring (13) facing away from the valve seat (11) is supported.

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