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), the closing element (9) of which is capable of opening or closing a passage in a valve seat (11) arranged in the valve housing (14), with a magnetic armature (2) provided for actuating the valve tappet (4), which is rigidly connected to the valve tappet (4), and with a return spring (8) which is arranged between the magnetic armature (2) and a magnetic core (5) fixed in the valve housing (14), wherein the magnetic armature (2) is supported at an end section facing away from the closing element (9) on the inner wall of the valve housing (14), wherein the magnetic armature (2) is pivotably received in the valve housing (14) about its longitudinal axis during its working stroke, for this purpose the magnetic armature (2) is connected to the inner wall of the valve housing (14) exclusively by a collar (12) provided on the end section of the magnetic armature (2). supported, characterized by,that the collar (12) attached to the end section of the magnetic armature (2) is convex.

Description

The invention relates to an electromagnetic valve, in particular for slip-controlled motor vehicle brake systems, according to the preamble of claim 1.From DE 197 00 980 A1, an electromagnetic valve of the indicated type has already become known, having a valve tappet arranged in a valve housing, the closing body of which valve tappet is able to open or close a passage in a valve seat arranged in the valve housing, having a magnet armature provided for actuating the valve tappet, which is rigidly connected to the valve tappet, and having a restoring spring arranged between the magnet armature and a magnet core fixed in the valve housing. As a result of a large-area contacting of the magnet armature along the inner wall of the valve housing, a relatively high friction results, which is to be assessed as disadvantageous with regard to the required actuating force.Furthermore, electromagnetic valves are known from DE 100 27 171 A1 and DE 10 2013 209 112 A1, in which the magnet armature can be pivoted about its longitudinal axis in the valve housing during its working stroke, wherein the magnet armature is supported exclusively by a collar on the inner wall of the valve housing.It is therefore the object of the present invention to design an electromagnetic valve of the stated type at low cost using the simplest possible means appropriate to function and to improve it in such a way that a simple, low-friction guidance of the magnet armature in the valve housing is ensured.This object is achieved according to the invention for the electromagnetic valve of the type specified by the characterizing features of claim 1.Further features and advantages of the invention will become apparent from the following description of two exemplary embodiments with reference to FIGS. 1 and 2.The following are shown: FIG. 1 is a longitudinal section of an electromagnetic valve according to the invention in the electromagnetically non-excited magnet armature position, in which the valve passage is closed by the closing body, FIG. 2 shows the electromagnetic valve according to FIG. 1 in the electromagnetically excited position of the magnet armature, in which the valve passage is completely released from the closing body with lateral offset.In the following, the essential elements of the electromagnetic valve according to the invention, which is preferably used for slip-controlled motor vehicle brake systems, will be explained first with reference to FIG. 1. The electromagnetic valve shown consists of functional elements known per se. This includes a valve passage 10 arranged in a valve housing 14 which can be closed by means of a valve tappet 4 arranged on a magnet armature 2 under the action of a restoring spring 8 or can be opened continuously by means of a magnet coil, not shown. For this purpose, the magnet armature 2 is accommodated in the valve housing 14 so as to be axially movable over a defined working stroke, wherein the restoring spring 8 is supported with its spring end facing away from the magnet armature 2 on a magnet core 5 closing the valve housing 14. The magnetic core 5 is consequently pressed as a closure plug into an austenitic housing sleeve 15 which, as a component of the valve housing 14, is welded to a thick-walled, rigid tubular body 16 which ensures the secure fastening in a valve receiving bore of a valve receiving body.The electromagnetic valve depicted in FIG. 1 is closed in the electromagnetically non-excited position, for which purpose the restoring spring 8 arranged above the magnet armature 2 is supported directly on the valve tappet 4, which is accommodated in sections within a coaxial bore 1 of the magnet armature 2. By means of a suitable electronic analog control, the valve coil to be plugged onto the valve housing 14 can be controlled in a current-proportional manner, whereby the prerequisite for continuously controlling the valve throughput in the valve passage 10 is provided.For precise adjustment, an adjustment sleeve 3 is fixed in the bore 1 of the magnet armature 2, in which the valve tappet 4 is fastened in sections. The adjusting sleeve 3 ensures a particularly simple, continuously variable adjustment of the residual air gap. As can be seen from the drawing, the adjusting sleeve 3 has a projection 6 on the end face of the magnet armature 2 facing the magnet core 5, the axial extent of which projection corresponds to the residual air gap between the magnet armature 2 and the magnet core 5 which is to be maintained precisely in the event of electromagnetic excitation. For this purpose, the adjusting sleeve 3 can be adjusted in any desired manner in sections by means of a sliding press fit in the bore 1 of the magnet armature 2.In order to prevent undesired magnetic leakage fluxes and also the so-called magnetic adhesion of the magnet armature 2 to the magnet core 5, the adjusting sleeve 3 is produced from a material which does not conduct the magnetic flux, in particular an austenitic steel.In the same way of attachment, the valve tappet 4 is fixed in the adjusting sleeve 3, wherein the press-fit 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 restoring spring 8.With regard to the further details of the construction of the valve housing 14, reference is hereby made to the special feature of the tubular body 16, which is connected on the end side opposite the housing sleeve 15 to a further thin-walled, pot-shaped housing sleeve 17, which has a radially encircling collar, which is fixed in a recess 13 on the tubular body 6 in a plastically deformed manner by means of a suitable tool. The further housing sleeve 17 consists of a hardened, ferritic material in order to be able to design the valve seat 19 in a manner such that it is as free of wear as possible at the base of the pot-shaped housing sleeve 1 in a manner such that it can be deformed. The valve passage 10 arranged in the valve seat 19 and the passage 20 arranged in the wall of the further housing sleeve 17 can then be produced together in a particularly cost-effective manner by the punching or stamping method.The design features presented thus result in an electromagnetic valve whose residual air gap can be adjusted easily and precisely by means of the adjustment sleeve 3 pressed into the bore 1 of the magnet armature 2 by the adjustment sleeve 3 being displaced only until the desired protrusion 6 is reached on the upper side of the magnet armature 2, wherein the protrusion 6 corresponds to the dimension of the residual air gap.In order to be able to compensate for the tolerances occurring during the production of the restoring spring 8, the installation space 7 required for the restoring spring 8 is adjusted just as simply and precisely in that the restoring spring 4 is supported on the end face of the valve tappet 4, while the valve tappet 4 is displaced continuously in the second holding section 10 of the adjusting sleeve 3 until a defined spring length is reached.For the purpose of guiding the magnet armature 2 in the valve housing 14 as low as possible, the magnet armature 2 is supported according to the invention exclusively on its end section facing away from the closing body 9 on the inner wall of the valve housing 14 with an extremely small surface area and thus with minimized friction in a contact point P 1, so that the magnet armature 2 can swivel slightly (approximately 0.5-1.0 angular degree) about its longitudinal axis when electrically excited during its working stroke without further contact with the inner wall of the valve housing 14. For unhindered execution of the pivoting movement, the magnet armature 2 has for this purpose a collar 12 provided at the end section of the magnet armature 2, which collar is designed convexly for execution of the pivoting movement and, in the preferred embodiment, has the contour of a spherical cap.In addition, in order to ensure a sufficiently large radial distance between the lateral surface of the magnet armature 2 and the inner wall of the valve housing 14, the magnet armature 2 is conically tapered in the direction of the closing body 9, so that in the case of a pivoting movement the magnet armature 2 does not touch the inner wall of the tubular body 16 at all.Instead of the conical tapering of the magnet armature 2, it is likewise feasible to expand the valve housing 14 in the manner of a funnel along the magnet armature 2 in the direction of the valve passage 10, as a result of which contact of the magnet armature 2 with the tubular body 16 is likewise reliably avoided in the specific exemplary embodiment.When the valve housing 14 is further viewed, it is evident that the lateral surface of the valve seat 11 integrated in the housing sleeve 17 has a conical sealing seat which is flared in the direction of the closing body 9 in such a way that the closing body 9 according to FIG. 2 opens the passage 10 in the valve seat 11 with a radial offset when it is lifted from the valve seat 11.According to FIG. 2, after the closing body 9 has been lifted from the valve seat 11, it is guided along the funnel-shaped lateral surface of the valve seat 11 over the entire working stroke of the magnet armature 2, so that ultimately the funnel angle of the valve seat 11 and the distance of the valve seat 11 from the contact point P 1 of the collar 12 bearing against the valve housing 14 (housing sleeve 15) determine the possible unimpeded radial deflection of the magnet armature 2. The magnet armature 2 is thus always guided precisely in the valve housing 14 in the manner of a two-point support during its entire working stroke, in that the collar 12 in any desired stroke position of the magnet armature 2 is supported only in the first contact point P 1 on the inner wall of the valve housing 14 and the closing body 9 is supported at a second contact point P 2 in the valve seat 11. For this purpose, the closing body 9 preferably has the contour of a spherical cap which is formed on the pointed end of the valve tappet 4 protruding from the magnet armature 2.List of reference characters1 Bore 2 Magnet armature 3 Adjusting sleeve 4 Valve tappet 5 Magnet core 6 Projection 7 Installation space 8 Restoring spring 9 Closing body 10 Valve passage 11 Valve seat 12 Collar 13 Recess 14 Valve housing 15 Housing sleeve 16 Tubular body 17 Housing sleeve

Claims

Electromagnetic valve for slip-controlled motor vehicle solenoids, having a valve tappet (4) which is arranged in a valve housing (14) and the closing body (9) of which is capable of opening or closing a passage in a valve seat (11) arranged in the valve housing (14), having a magnet armature (2) which is provided for actuating the valve tappet (4) and is rigidly connected to the valve tappet (4), and having a restoring spring (8) which is arranged between the magnet armature (2) and a magnet core (5) fixed in the valve housing (14), wherein the magnet armature (2) is supported on the inner wall of the valve housing (14) at an end section facing away from the closing body (9), wherein the magnet armature (2) is accommodated in the valve housing (14) such that it can be pivoted about its longitudinal axis during its working stroke, For this purpose, the magnet armature (2) is supported on the inner wall of the valve housing (14) exclusively by a collar (12) provided on the end section of the magnet armature (2), characterized in that the collar (12) attached to the end section of the magnet armature (2) is of convex design.Electromagnetic valve according to Claim 1, characterized in that the magnet armature (2) is tapered conically in the direction of the closing body (9).Electromagnetic valve according to Claim 1, characterized in that the valve housing (14) is widened in the form of a funnel along the magnet armature (2) in the direction of the valve passage (10).Electromagnetic valve according to Claim 1, characterized in that, after the valve seat (11) has been released, the closing body (9) is guided along the lateral surface of the valve seat (11) over the entire working stroke of the magnet armature (2).Electromagnetic valve according to Claim 4, characterized in that the lateral surface of the valve seat (11) is widened in the form of a funnel in the direction of the closing body (9), with the result that the closing body (9) opens up the passage in the valve seat (11) with a radial offset when it is lifted off the valve seat (11).Electromagnetic valve according to Claim 5, characterized in that the valve seat (11) has a conical sealing seat.Electromagnetic valve according to Claim 1, characterized in that the closing body (9) has the contour of a spherical cap which is formed on the pointed end of the valve tappet (4) protruding from the magnet armature (2).Electromagnetic valve according to Claim 1, characterized in that the magnet armature (2) is guided in the valve housing (14) in the manner of a two-point support during its entire working stroke, with linear contact, for which purpose the collar (12) is supported at a first contact point (P1) on the inner wall of the valve housing (14) and the closing body (9) is supported at a second contact point (P2) in the valve seat (11).

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