Solenoid Valve having Adjustable Spring Force

Abstract

A solenoid valve, in particular for controlling a brake pressure of a wheel brake of a motor vehicle, includes a pole core, an axially moveably mounted armature, a valve element, a closure element, a plunger, and a pressure spring. One end of the armature is associated with the pole core. The valve sealing element is arranged at another end of the armature. The armature has an axial through-opening. The closure element is force-lockingly and/or interlockingly retained in the axial through-opening in a selectable position. The plunger is axially moveably mounted in the axial through-opening, which provides a connection to the pole core in an installation position. The pressure spring is positioned in the axial through-opening and is retained in a pretensioned manner between the plunger and the closure element. The closure element is designed as a three-dimensionally convex element.

Claims

1. A solenoid valve for controlling a brake pressure of a wheel brake of a motor vehicle, comprising: a pole core; an axially moveably mounted armature including an axial passage, one end of the armature assigned to the pole core; and a valve sealing element arranged at another end of the armature; a closure element configured as a three-dimensionally convex body and retained in a selectable position in the axial passage by force fit and/or form fit; a plunger axially moveably mounted in the axial passage and providing a connection to the pole core in an installation position; and a compression spring positioned in the axial passage and held under preload between the plunger and the closure element.

2. The solenoid valve as claimed in claim 1, wherein the three-dimensionally convex body has includes round forms.

3. The solenoid valve as claimed in claim 1, wherein the three-dimensionally convex body is pressed into the axial passage.

4. The solenoid valve as claimed in claim 3, wherein the three-dimensionally convex body bears against the axial passage around the entire periphery.

5. The solenoid valve as claimed in claim 1, wherein the three-dimensionally convex body includes an oval longitudinal section.

6. The solenoid valve as claimed in claim 1, wherein the three-dimensionally convex body is configured as an ellipsoid.

7. The solenoid valve as claimed in claim 1, wherein the three-dimensionally convex body is configured as a ball.

8. The solenoid valve as claimed in claim 1, wherein the armature includes at least one longitudinal groove on an outer casing surface of the armature.

9. The solenoid valve as claimed in claim 1, further comprising: a sleeve arranged in the axial passage of the armature and configured to fix and/or guide the plunger.

10. The solenoid valve as claimed in claim 1, wherein the three-dimensionally concave convex body defines the closure element and the valve sealing element.

11. An armature for a solenoid valve for controlling a brake pressure of a wheel brake of a motor vehicle, comprising: an axial passage, wherein: one end of the armature is assigned to a pole core and a valve sealing element is arranged at another end of the armature; a closure element configured as a three-dimensionally convex body and retained in a selectable position in the axial passage by force fit and/or form fit; a plunger is axially moveably mounted in the axial passage and configured to provide a connection to the pole core in an installation position; a compression spring is positioned in the axial passage and is held under preload between the plunger and the closure element; and the armature is axially moveably mounted in the solenoid valve.

12. A method for producing an armature for a solenoid valve the method comprising: introducing a sleeve into an axial passage of the armature; introducing a plunger into the axial passage after introducing the sleeve; introducing a compression spring into the axial passage after introducing the plunger; inserting the closure element into the axial passage until the compression spring is preloaded between the closure element and the plunger and reaches a desired preload force; and applying a specific counter-force to the plunger in order to determine the preload force of the compression spring.

13. The solenoid valve as claimed in claim 5, wherein the three-dimensionally convex body is configured as an ovoid.

14. The solenoid valve as claimed in claim 6, wherein the three-dimensionally convex body is configured as a rotational ellipsoid.

Description

EMBODIMENTS

[0033] It is pointed out that the features listed individually in the description may be combined with each other in any technically sensible fashion and disclose further embodiments of the invention. Further features and the suitability of the invention arise from the description of exemplary embodiments with reference to the attached figures.

[0034] The drawings show:

[0035] FIG. 1 an extract of a diagrammatic, sectional view of a solenoid valve according to an embodiment according to the invention.

[0036] FIG. 1 shows in a longitudinal, sectional depiction a solenoid valve 1 for a brake system of a motor vehicle. The solenoid valve 1 comprises a housing 14 which is formed as a cylindrical housing and in which an also cylindrical armature 3 is arranged so as to be longitudinally displaceable, in particular axially movable. A pole core 2, which is connected to or arranged in series with the armature 3, is assigned to an upper end of the armature 3 and fixed in the housing 14 for example by means of a weld connection. A valve body 15 held by the housing 14 is assigned to the opposite lower end of the armature 3 and has a through-flow opening 16. The valve body 15 is furthermore provided with a sealing seat 10.

[0037] The armature 3 has an axial receiver configured as an axial passage 4 which extends centrally through the armature 3. Towards the lower end of the armature 3, the axial passage 4 is formed tapering such that it has a radially inwardly projecting protrusion 7. A three-dimensionally convex body 9 is pressed into this protrusion 7. The axial length of the protrusion 7 defines the positionability of the body 9 in the armature 3. The body 9 is designed as a closure element of the axial passage 4 and as a valve sealing element so that, in a defined position of the solenoid valve 1, it cooperates sealingly with the valve seat 10 in order to close the through-flow opening 16. The outer diameter of the body 9 and the inner diameter of the axial passage 4, or the inner diameter of the protrusion 7, are selected so as to form a press-fit, so that on assembly of the armature 3, the body 9 is pressed axially into the axial passage 4 up to a desired position. The body 9 is then held there by force fit by the press joint at the armature 3.

[0038] A longitudinally displaceable plunger 8 (also called a pressure piece) is also positioned in the axial passage 4 of the armature 3, but is spaced apart from the closure element 9. The plunger 8 has a substantially cylindrical base body. The plunger 8 extends through the upper end of the armature 3 in the direction of the pole core 2 and bears against this in the fitted state.

[0039] A compression spring 11 is also arranged in the axial passage 4 between the body 9 and the plunger 8, and in the present case is configured as a coil spring which is preloaded between the closure element 9 and the plunger 8. The compression spring 11 lies directly on the body 9. Depending on the positioning of the body 9, the contact position of the compression spring 11 in the lower region of the armature 3 is thus defined. The plunger 8 and the body 9 cooperate such that the compression spring 11, positioned between the plunger 8 and the body 9, is loaded with a force.

[0040] Furthermore, a sleeve 5 is introduced, in particular pressed, into the axial passage 4. The sleeve 5 offers a guide for a plunger 8. The upper end of the sleeve 5 is formed so as to be flush with the upper end of the armature 3. Furthermore, the lower end of the sleeve 5 forms an axial stop 6 for the plunger 8. A gap 12 is formed between the sleeve 5 and the plunger 8. This gap 12 allows firstly a degree of radial play and secondly an escape (or slight flow) of the fluid in the axial passage 4 when the armature 3 is moved in the solenoid valve 1. Furthermore, the armature 3 has grooves 13 to allow a fluid balance on movement of the armature 3 in the armature sleeve 5.

[0041] Preferably, however, the three-dimensionally convex body 9 is inserted iteratively or in sections ever further into the axial passage 4 until the desired preload force is reached, wherein the preload force is measured after each insertion process of the three-dimensionally convex body 9, in particular by loading the plunger 8 with a defined counter-force in the direction of the compression spring 11. Advantageously, the counter-force is selected such that it corresponds to the desired preload force. When the plunger 8 can no longer be moved axially into the armature 3 by the counter-force, the desired preload force is reached. Then the armature 3 with the three-dimensionally convex body 9, the compression spring 11 and the plunger 8 are mounted as a premounted assembly. Thus in a simple fashion, the solenoid valve 1 allows the preload force of the compression spring 11 to be set precisely and hence to compensate for given component tolerances.