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

Abstract

Electromagnetic valve for slip-controlled motor vehicle braking systems with a valve tappet (4) arranged in a valve housing (14), which is capable of opening or closing a valve passage (13) in a hollow cylindrical valve seat body (19) which has an interference fit section (24) for fixing in the valve housing (14), with a magnetic armature (2) provided for actuating the valve tappet (4), which is penetrated by a bore (1) to receive the valve tappet (4), and with a return spring (8) acting on the valve tappet (4), the end of which of the spring facing away from the magnetic armature (2) is supported on a magnetic core (5) which is arranged on the end face of the valve housing (14) facing away from the valve seat body (19), wherein the valve seat body (19) has an axial stop (20) on its outer surface which is located on an end face of the valve housing (14) facing away from the magnetic core (5). supported, characterized in that it is elastic,In the radial deformation of the valve housing (14) directed towards the outer surface of the valve seat body (19), a circumferential recess (22) is provided on the outer surface of the valve seat body (19), which is arranged between the press-fit surface (24) of the valve seat body (19) in the valve housing (14) and the axial stop (20).

Description

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

[0002] From WO 2003 / 093 083 A1, an electromagnetic valve of the type described is already known, the magnetic armature of which has a bore through it to receive a valve tappet. A return spring rests on the valve tappet, and the valve tappet is moved within the magnetic armature to adjust the spring preload. Under the action of the return spring, the valve tappet, with its valve closing element, rests on a sleeve-shaped valve seat body, which is held in the valve housing by an interference fit. Since the valve seat body is subject to not only mechanical but also hydraulic forces under temperature fluctuations, considerable effort must be paid to selecting a suitable material and ensuring a precise interference fit in order to prevent unintentional displacement of the valve seat body within the valve housing.

[0003] Furthermore, an electromagnetic valve is known from DE 198 36 494 A1 in which a hat- or pot-shaped valve seat body is inserted into a housing opening and is supported or rests against the front face of the housing opening with a flange that is directed radially outwards.

[0004] From DE 10 2012 214 510 A1, an electromagnetic valve is known in which a valve seat body is fixed in a tapered area of ​​a housing sleeve.

[0005] DE 101 09 178 A1 also discloses an electromagnetic valve in which a valve seat body is at least partially inserted into a housing opening and is supported or rests against it with an external axial stop.

[0006] The object of the present invention is to implement an electromagnetic valve of the specified type in a cost-effective manner using the simplest possible functional means and to improve it in such a way as to ensure simple, precise positioning of the valve seat body in the valve housing, while also creating good conditions that allow for a structural extension of the valve seat body.

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

[0008] Further features and advantages of the invention will become apparent from the following description of several exemplary embodiments based on the Fig. 1 to 3 stand out.

[0009] They show: Fig. 1 A first embodiment of the invention is shown in a longitudinal section through a solenoid valve, the valve seat body of which has a collar-shaped axial stop for fixing it in the valve housing, Fig. 2 a second embodiment not according to the invention by means of a longitudinal section through a solenoid valve, the valve seat body of which has a clipped-on filter element, Fig. 3 a third embodiment not according to the invention shown by means of a longitudinal section through a solenoid valve in whose valve seat body a filter element is pressed in.

[0010] The following section will first outline the commonalities of all the [unclear] in the Fig. Figures 1 to 3 describe the solenoid valves, which are preferably used for slip-controlled motor vehicle braking systems. The solenoid valves shown consist of functional elements known per se. These include a valve passage 13 arranged in a valve housing 14, which can be closed by means of a valve plunger 4 arranged on a magnetic armature 2 under the action of a return spring 8 or opened by means of a solenoid coil (not shown). For this purpose, the magnetic armature 2 is guided axially movable in the valve housing 14 along its outer surface over a defined working stroke, with the return spring 8 bearing against a magnetic core 5 that closes the valve housing 14 at its end facing away from the magnetic armature 3.In the three exemplary embodiments presented, the magnetic core 5 is pressed into an austenitic housing sleeve 15 as a magnetizable sealing plug, which is welded as part of the valve housing 14 to a thick-walled, rigid tube body 16, which ensures secure fastening in a valve receiving bore of a valve receiving body.

[0011] All illustrated solenoid valves are closed in the electromagnetically unexcited position. In this position, the return spring 8, located above the magnetic armature 2, bears directly against the valve plunger 4, which is partially enclosed within a coaxial bore 1 of the magnetic armature 2. A suitable electronic analog control allows the valve coil, which is mounted on the valve housing 14, to be controlled proportionally to the current, thus providing the prerequisite for stepless control of the valve flow rate.

[0012] To ensure precise adjustment of the in the Fig. To ensure the proper functioning of the solenoid valves shown in 1 to 3, an adjusting sleeve 3 is fixed in the bore 1 of the magnetic armature 2, in which, for example, according to the Fig. 1. Additionally, the valve tappet 4 is attached section by section. The adjusting sleeve 3 ensures a particularly simple, stepless adjustment of the residual air gap (RLS).

[0013] To prevent unwanted magnetic stray fluxes as well as the so-called magnetic sticking of the magnetic armature 2 to the magnetic core 5, the adjusting sleeve 3 is made of a material that does not conduct magnetic flux, in particular an austenitic steel.

[0014] As can be seen from all the figures, the adjusting sleeve 3 has a projection 6 on the end face of the magnetic armature 2 facing the magnetic core 5, the axial extent of which corresponds to the residual air gap RLS between the magnetic armature 2 and the magnetic core 5, which must be precisely maintained during electromagnetic excitation. For this purpose, the adjusting sleeve 3 can be adjusted section by section by means of a sliding press fit in the bore 1 of the magnetic armature 2 as required.

[0015] The same fastening method is used in the Fig. 1 the valve tappet 4 is also fixed in the adjusting sleeve 3, wherein the insertion depth of the valve tappet 4 in the adjusting sleeve 3 is defined by an installation space 7 required in the adjusting sleeve 3 for the return spring 8.

[0016] The frictional force of the sliding press fit acting between the adjusting sleeve 3 and the magnetic armature 2, as well as between the adjusting sleeve 3 and the valve tappet 4, is at least as large in magnitude as the mechanical and hydraulic forces acting on the adjusting sleeve 3 and the valve tappet 4 during valve switching.

[0017] In the Fig. 1 The adjusting sleeve 3 has two retaining sections 9, 10, the first retaining section 9 comprising the press connection between the outer shell of the adjusting sleeve 3 and the bore 1, while the second retaining section 10 is defined by the press connection between the inner shell of the adjusting sleeve 3 and the valve tappet 4.

[0018] Furthermore, it is evident from the Fig. Figure 1 shows that, following the first retaining section 9, an annular space 23 is provided in the area of ​​the second retaining section 10 between the adjusting sleeve 3 and the bore 1 in the magnetic armature 2, so that a pressure equalization bore 11 located in the adjustment sleeve 3 in the transition area between the first and second retaining sections 10 is in hydraulically pressure-equalizing communication via the annular space 23 with an installation space 7 which accommodates the return spring 8 in the adjusting sleeve 3. Furthermore, the annular space 23 allows a tolerance-compensating radial expansion of the second retaining section 10, which facilitates the pressing in of the valve tappet 4 into the adjusting sleeve 3.

[0019] From the Fig. It is further evident from figures 1 to 3 that the adjusting sleeve 3 is provided at least at one sleeve end with a collar 12 which acts as an axial stop on the magnetic core 5 section by section.

[0020] The non-magnetic properties of the adjusting sleeve 3 and the collar 12 attached to it advantageously result in a non-magnetic and therefore friction-minimized guide for the valve tappet 4 and the magnetic armature 2 in the valve housing 14.

[0021] Since according to the Fig. Since the valve tappet 4 is pressed directly into the non-magnetic adjusting sleeve 3, there is consequently no contact with the magnetic material of the magnetic armature 2, thus ensuring magnetic decoupling and preventing any unwanted magnetization of the valve tappet 4, regardless of the material chosen, which could adversely affect the valve control.

[0022] Regarding the structure of the in the Fig. With regard to the valve housing 14 shown in Figures 1-3, it should be noted that the illustrated solenoid valves each have a thick-walled tube body 16 in which the valve seat body 19 is pressed in as a separate component. A housing sleeve 15, 17, is attached to the tube body 19 above and below, respectively. The upper housing sleeve 15 is welded to the tube body 16, while the lower housing sleeve 17, located on the end face opposite the housing sleeve 15, has a radially circumferential collar that is plastically deformed and fixed in a recess 18 on the tube body 6 using a suitable tool. The lower housing sleeve 17 is preferably made of an austenitic, thin-walled steel, with a passage 20 arranged in the wall of the lower housing sleeve 17 being produced cost-effectively by stamping or embossing.

[0023] As from the Fig. As can be seen from 1 to 3, in the lower housing sleeve 17 of the valve housing 14 there is a guide area provided for the magnetic armature 2, which has a pressure equalization channel 29 in sections along the inner wall of the lower housing sleeve 17, which is formed particularly simply by a plastic deformation of the housing sleeve 17 produced by deep drawing.

[0024] As can be seen from all the figures, the valve seat body 19 has an axial stop 20 on its outer surface, which is supported against an end face of the valve housing 14, designed as a solid tubular body 16, facing away from the magnetic core 5. This ensures precise positioning of the valve seat body 19 in the valve housing 14, and reliably prevents displacement of the valve seat body 19 within the valve housing 14, even when the valve seat body 19 is subjected to hydraulic pressure from below it. In a preferred embodiment, the axial stop 20 on the valve seat body 19 is designed as a stepped shoulder, with its preferably annular projection 21 extending from the end face of the valve housing 14.

[0025] According to the Fig. To enable elastic radial deformation of the valve housing 14, designed as a thin-walled housing sleeve 17, directed towards the outer surface of the valve seat body 19, a circumferential recess 22 is provided on the outer surface of the valve seat body 19. This recess is located between an interference fit 24 of the valve seat body 19 in the housing sleeve 17 and the axial stop 20. This ensures that, due to its resilient flexibility, the housing sleeve 17 can be inserted into the valve receiving bore 30 with minimal insertion force, without jamming or wear, while maintaining generous fit tolerances and ensuring sufficient sealing.

[0026] Contrary to the Fig. 1 is carried out in the exemplary embodiment according to Fig. 2. The solenoid valve is fixed and sealed in the valve receiving bore 30 not by the thin-walled housing sleeve 17, but by a projection 21 of the valve seat body 19 projecting from the end face of the valve housing 14. This projection has a circumferential sealing surface 25 on its outer surface, which is used to fix and seal the solenoid valve by means of an interference fit in the valve receiving bore 30. A filter element 26 is attached to the projection 21. This filter element has a collar 27 that is engaged, like a clip, in a groove-shaped undercut 28 on the outer surface of the projection 21. The valve seat body 19 is designed to form the Fig. 1, Fig. The details shown in the illustrations are preferably produced by machining free-cutting steel using a lathe.

[0027] Alternatively to Fig. 2 is in the Fig. 3. A filter element 26 is pressed into a cavity of the annular projection 21. In contrast to Fig. 1, Fig. 2 The valve seat body 19 is produced cost-effectively by deep drawing of thin-walled austenitic steel for the formation of the projection 21 sealing in the valve receiving bore 30, the axial stop 19 bearing against the housing sleeve 17 and the press-fit section held in the housing sleeve 17, wherein the valve passage 13 to be closed by the valve tappet 4 is provided with a surface hardening for wear protection. Reference symbol list 1 bore 2 magnetic anchors 3 Adjustment sleeve 4 valve tappets 5 magnetic core 6 overhang 7 Installation space 8 Return spring 9 Stop section 10 Stop section 11 Pressure equalization bore 12 bundles 13 Valve passage 14 Valve housings 15 Housing sleeve 16 pipe bodies 17 Housing sleeve 18 Exclusion 19 Valve seat bodies 20 Axial stop 21 lead 22 Exclusion 23 annular space 24 Press fit section 25 sealing surface 26 filter element 27 Stand-up collars 28 Undercut 29 Pressure equalization channel 30 Valve mounting bore

Claims

[1] Electromagnetic valve for slip-controlled motor vehicle braking systems with a valve tappet (4) arranged in a valve housing (14), which is capable of opening or closing a valve passage (13) in a hollow cylindrical valve seat body (19) which has an interference fit section (24) for fixing it in the valve housing (14), with a magnetic armature (2) provided for actuating the valve tappet (4), which is penetrated by a bore (1) to receive the valve tappet (4), and with a return spring (8) acting on the valve tappet (4), the end of which of the spring facing away from the magnetic armature (2) is supported on a magnetic core (5) which is arranged on the end face of the valve housing (14) facing away from the valve seat body (19), wherein the valve seat body (19) has an axial stop (20) on its outer surface which is located on an end face of the valve housing (14) facing away from the magnetic core (5). supports, characterized by, that for elastic radial deformation of the valve housing (14) directed towards the outer surface of the valve seat body (19) a circumferential recess (22) is provided on the outer surface of the valve seat body (19), which is arranged between the press fit surface (24) of the valve seat body (19) in the valve housing (14) and the axial stop (20).

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