Solenoid valve

Abstract

Electromagnetic valve for motor vehicle wheel slip control systems with a valve housing provided with at least one pressure medium channel, in which a valve tappet is movably guided, the tappet being directed with its valve closing element towards a valve seat, with a magnetic armature attached to the valve tappet which, depending on the electromagnetic excitation of a valve coil attached to the valve housing, performs a stroke movement on a magnetic core arranged in the valve housing, and with a spring which, in the electromagnetically unexcited valve position, positions the magnetic armature at a defined axial distance from the magnetic core, so that the magnetic armature is separated from the magnetic core by an intermediate space, for this purpose the spring is supported at one end on the magnetic core and bears at its other end against a region of the valve tappet facing away from the valve seat, which is pressed into a stepped bore of the magnetic armature to vary the preload force of the spring.wherein the valve tappet (7) is fixed in the stepped bore (13) of the magnetic armature (5) under the action of two successive, differently sized pressing forces, characterized in that a non-magnetic residual air gap disk (18) is arranged between the magnetic core (3) and the magnetic armature (5), which is held on the magnetic core (3) under the force of the spring (6) and wherein the residual air gap disk (18) has a hole (19) in the middle for bearing and guiding a guide pin (16) formed on the valve tappet (7), which extends through the hole (19) with play into a blind hole (17) of the magnetic core (3).

Description

[0001] The invention relates to a solenoid valve for motor vehicle wheel slip control systems according to the preamble of patent claim 1.

[0002] DE 102 54 342 A1 already discloses a solenoid valve of the generic type, whose spring arranged between the magnet armature and the magnet core must exhibit a precise preload force so that the valve tappet achieves the desired opening characteristic. The preload force of the spring is influenced not only by the precision of the spring manufacturing, but also by the dimensional tolerances of the individual valve components and the offset of the valve tappet in the magnet armature, since the spring rests directly on the valve tappet, which is secured in the magnet armature only by a sliding press fit.

[0003] DE 10 2004 022 820 A1 discloses an electromagnetic valve in which the valve closure member has two grooves and a shoulder that are successively pressed into the solenoid armature. The grooves create different pressing forces, so that the valve stem is fixed in the stepped bore of a solenoid armature under the effect of two successive, differently sized pressing forces.

[0004] Furthermore, DE 198 24 500 A1 discloses an electromagnetic valve in which a valve tappet can be mounted at different positions in the solenoid armature to vary the preload force. The valve tappet is mounted by pressing. The valve tappet has five constrictions suitable for generating different press-in forces.

[0005] It is an object of the present invention to improve a solenoid valve of the generic type while maintaining a structure as simple as possible in such a way that the preload force of the spring can be permanently and precisely adjusted in a simple manner, independent of the aforementioned imponderables.

[0006] This object is achieved according to the invention for a solenoid valve of the type specified with the characterizing features of patent claim 1.

[0007] Further features and advantages of the invention are explained below with reference to several drawings: They show: Fig. 1 a longitudinal section through a normally closed solenoid valve with the features for spring adjustment by means of a valve tappet pressed into the magnet armature, Fig. 2 starting from the object according to Fig. 1 a plan view of a residual air gap disc positioned between the magnetic core and the magnetic armature, Fig. 3 a design of the object according to Fig. 1, for which purpose an extension is provided on the valve tappet, which extends through the residual air gap disc into a blind hole in the magnetic core, Fig. 4 starting from the object to Fig. 3 a top view of the residual air gap disc positioned between the magnetic core and the magnetic armature, in whose central hole the extension is guided with plain bearing play, Fig. 5 the solenoid valve Fig. 1, whose valve tappet is guided in a centering disc, which is fixed in the valve housing by means of a caulking.

[0008] The Fig. 1 shows an example of the conceptual valve structure for the Fig. 2-5 depict details of a normally closed solenoid valve, whose valve housing 1 is constructed as a solid tubular part using a lathe in a cartridge design. Adjoining the tubular part, as part of the valve housing 1, is a thin-walled valve sleeve, which is tightly sealed by a plug-shaped magnetic core 3.

[0009] In order to maintain a minimum axial distance, a non-magnetic residual air gap disc 18 is located below the magnetic core 3, the thickness of which corresponds to the required dimension of the magnetic armature residual air gap, taking into account the magnetic armature stroke, so that following an electromagnetic actuation of the magnetic armature 5, adhesion of the magnetic armature 5 to the magnetic core 3 is reliably avoided.

[0010] The magnet armature 5 accommodates a spring 6 known per se within a stepped bore 13, which spring 6 is arranged according to the Fig. 1 and Fig. 2 shown design as a compression spring with one winding end supported on the residual air gap disc 18 and which according to the Fig. 1, Fig. 3, Fig. 5 rests with the opposite winding end on a stop disk 4 attached to the valve tappet 7. The valve tappet 7 is consequently pressed against a valve seat 8 in the valve housing 1 under the action of the spring 6, so that in the electromagnetically non-excited valve position, a pressure medium channel 9 penetrating the valve housing 1 in the horizontal and vertical directions is interrupted.

[0011] By means of a valve coil to be mounted on the valve housing 1, the magnet armature 5 can be moved in the direction of the magnet core 3 by electromagnetic excitation in order to release the blockage of the pressure medium channel 9 by lifting the valve closing member 14 provided on the valve tappet 7 from the valve seat 8.

[0012] In order to adjust the preload force of the spring 6, the valve tappet 7 is pressed into the stepped bore 13 of the magnet armature 5 in such a way that at the same time the most precise, sensitive and secure positioning of the valve tappet 7 in the magnet armature 5 is ensured, for which purpose a first annular space 11 is provided between the valve tappet 7 and the magnet armature 4 for receiving a magnet armature material displaced under the action of a first press-in force on the valve tappet 7 and wherein adjacent to the first annular space 11 between the valve tappet 7 and the magnet armature 4 a second annular space 12 is arranged, which receives the further magnet armature material displaced within the stepped bore 13 under the action of a second press-in force on the valve tappet 7 which is increased compared to the first press-in force.The first press-in force is dimensioned such that the first annular space 11 is initially completely filled with the displaced magnet armature material and the magnet armature material is sufficiently compacted until a minimum strength is achieved between the valve tappet 7 and the magnet armature 5. By arranging the second annular space 12 directly behind the first annular space 11, the valve tappet can then be displaced into the final position relevant for the spring preload within the magnet armature 5 by applying a sufficiently increased excess force (the so-called second press-in force). Consequently, the spring 6 is also precisely adjusted in a rational manner under the effect of two successive, differently sized press-in forces on the valve tappet 7.

[0013] As can be seen from the Fig. 1, Fig. 3, Fig. 5, the two annular spaces 11, 12 are designed as two groove-shaped constrictions arranged one behind the other on the valve tappet 7, in front of which a shoulder 10 is arranged on the valve tappet 7 to displace the magnet armature material into the annular spaces 11, 12. By means of the shoulder 10, when the valve tappet 7 is pressed into the lower section of the stepped bore 13, the stepped bore 13 is plastically deformed in the direction of the two annular spaces 11, 12, so that first the first annular space 11 and then the second annular space 12 are filled and compacted with the material of the magnet armature 5 displaced into the two grooves, with a slight increase in the pressing force.This enables a precise adjustment of the spring force depending on the press-in depth of the valve tappet 7 in the stepped bore 13, wherein upon completion of the press-in process, the valve tappet 7 protrudes with its end facing away from the valve closing member 14 at a bore step 15 in the stepped bore 13, which receives a stop disk 4 acted upon by the valve tappet 7 and the spring 6.

[0014] According to the Fig. 3, the stop plate 4 is different from Fig. 1, Fig. 2 is designed as an annular disc through which a guide pin 16 formed on the valve tappet 7 extends into a blind hole 17 in the magnetic core 3, with the further special feature that the residual air gap disc 18 arranged between the magnetic core 3 and the magnetic armature 5 is not only held on the magnetic core 3 as a result of the force of the spring 6, but has a hole 19 in the middle for the sliding bearing and centering of the guide pin 16, which extends through the hole 19 with sufficient play into the blind hole 17 of the magnetic core 3. The magnetic armature 5 is thus guided with particularly low friction in the area of ​​the valve sleeve of the valve housing 1 as a result of the sliding bearing of the guide pin 16 in the hole 19.

[0015] Starting from Fig. 3 shows the Fig. 4 a perspective view of the residual air gap disc 18, which is centered in the valve sleeve of the valve housing 1, for which purpose the residual air gap disc 18 is supported with its outer circumference on the inner casing of the valve housing 1. Analogous to the representation of the residual air gap disc in Fig. 2 also shows the Fig. 3, Fig. 4, the residual air gap disc 18 has several recesses 2 along its outer circumference for unhindered flow, for which purpose the residual air gap disc 18 is preferably designed in a star-shaped or clover-leaf shape. An unhindered pressure medium exchange above and below the magnet armature 5 advantageously takes place via at least one longitudinal groove 21 along the outer surface of the magnet armature 5, wherein the recesses 2 on the residual air gap disc 18 in the Fig. 3, Fig. 4 is of particular importance in order to enable pressure exchange within the blind hole 17.

[0016] Finally, the design variant according to Fig. 5 as a supplement to the Fig. 1-4 a suitable guidance of the magnet armature 5 in the valve housing 1 by means of a centering disc 20 arranged between the magnet armature 5 and the valve seat 8, which is fixed by means of a caulking on the inner wall of the tubular valve housing 1, wherein the valve tappet 7 extends precisely guided through a centrally arranged opening of the centering disc 20 in the direction of the valve seat 8. List of reference symbols 1 valve housing 2 recess 3 magnetic core 4 stop disc 5 magnet armatures 6 spring 7 valve tappets 8 Valve seat 9 Pressure medium channel 10 paragraph 11 Annular space 12 Annular space 13 stepped bore 14 Valve closing element 15 drilling stages 16 guide pins 17 blind hole 18 residual air gap disc 19 holes 20 Centering disc 21 Longitudinal groove

Claims

[1] Electromagnetic valve for motor vehicle wheel slip control systems with a valve housing provided with at least one pressure medium channel, in which a valve tappet is movably guided, the valve closing member of which is directed towards a valve seat, with a magnet armature attached to the valve tappet, which, depending on the electromagnetic excitation of a valve coil attached to the valve housing, performs a lifting movement on a magnet core arranged in the valve housing, and with a spring which, in the electromagnetically non-excited valve position, positions the magnet armature at a defined axial distance from the magnet core, so that the magnet armature is separated from the magnet core by an intermediate space, for which purpose the spring is supported with one end on the magnet core and with its other end rests against a region of the valve tappet facing away from the valve seat, which region is pressed into a stepped bore of the magnet armature to vary the preload force of the spring,wherein the valve tappet (7) is fixed in the stepped bore (13) of the magnet armature (5) under the effect of two successive, differently sized pressing forces, , characterized by that a non-magnetic residual air gap disc (18) is arranged between the magnetic core (3) and the magnetic armature (5), which is held on the magnetic core (3) under the force of the spring (6), and wherein the residual air gap disc (18) has a hole (19) in the middle for supporting and guiding a guide pin (16) formed on the valve tappet (7), which guide pin extends through the hole (19) with play into a blind hole (17) of the magnetic core (3). [2] Solenoid valve according to claim 1, characterized by that the residual air gap disc (18) is centered in the valve housing (1), for which purpose the residual air gap disc (18) is supported with its outer circumference on the inner casing of the valve housing (1).

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