# Patent

## Title
Solenoid valve for controlling a fluid

## Abstract

A solenoid valve for controlling a fluid is disclosed. The solenoid includes an armature, a pole core, wherein a working gap is provided between the armature and the pole core, a valve member which is connected to the armature and can be moved together with the armature, a valve body with a through-opening on which a valve seat is formed, wherein the valve member opens and closes the through-opening on the valve seat, a return element which applies a return force to the valve member in order to return the valve member to a closed state, a spring element which is arranged in the working gap, and an adjusting device which is in contact with the spring element in order to adjust a spring force of the spring element.

## Background
Cross Reference is made to copending U.S. patent application Ser. No. 13/032,515 entitled “Solenoid Valve for Controlling a Fluid,” filed on Feb. 22, 2011.
This application claims priority under 35 U.S.C. §119 to German patent application no. 10 2010 002 224.1, filed Feb. 23, 2010 in Germany, the disclosure of which is incorporated herein by reference in its entirety.
The present disclosure relates to a solenoid valve which is closed in the de-energized state and has the purpose of controlling a fluid.
BACKGROUND
Solenoid valves which are closed in the de-energized state and have the purpose of controlling a fluid are known from the prior art in various embodiments, in particular, for example, as outlet valves for ABS/TCS/ESP devices in motor vehicles. These solenoid valves have a valve member which is connected to the armature and the pole core. A return element is provided between the pole core and the armature. The valve member opens a through-opening on a valve seat, and respectively closes it again. Such a valve element is known, for example, from DE 10 2007 031 981 A1.
SUMMARY
The solenoid valve for controlling a fluid with the features of the present disclosure has, in contrast, the advantage that an adjusting device for supporting an additional spring element is inserted, in order to adjust the force effect of the spring element in its interaction with the return element. This is achieved according to the disclosure in that the solenoid valve for controlling a fluid comprises an armature, a pole core, wherein a working gap is provided between the armature and the pole core, and a valve member which is connected to the armature and can be moved together with the armature. The solenoid valve also has a valve body with a through-opening on which a valve seat is formed, wherein the valve member opens and closes the through-opening on the valve seat, a return element which applies a return force to the valve member in order to return the valve member to a closed state, and the spring element which is arranged in the working gap. Furthermore, the adjusting device is provided, which is adjustable and is in contact with the spring element in order to adjust a spring force of the spring element. The adjustment of the spring force of the spring element makes it possible, when the solenoid valve is actuated, to counteract the magnetic force which increases exponentially as the axial working gap becomes smaller. This considerably improves the adjustability of the solenoid valve. In addition, dimensional deviations can be compensated specifically for each solenoid valve by this means, and a constant spring force of the solenoid valves can therefore always be ensured.
Preferred developments of the disclosure are set forth herein.
According to one preferred embodiment of the disclosure, the adjusting device is arranged on the pole core. As a result, a simple and cost-effective adjusting device with a minimum number of components and a short mounting time is implemented, said device permitting precise adjustment or calibration of the solenoid valve. In addition, the spring element can be made available as a cost-effective spring washer.
Furthermore, the adjusting device is arranged in a central recess on the pole core. This makes it possible to implement a compact design with minimal overall volume.
The spring element preferably has a central opening and is of annular design. Furthermore, the adjusting device preferably makes contact with an internal circumference of the spring element. As a result, the spring element can be made available as a cost-effective annular spring washer. Precise adjustment of the spring force of the spring element which brings about closing is made possible through the support of the internal circumference of the spring element on the adjusting device and of the external circumference of the spring element on the armature.
In a further advantageous embodiment of the disclosure, the adjusting device is embodied as a solid cylinder or alternatively as a tubular element. This permits simple and cost-effective manufacture of the adjusting device with a small number of fabrication steps and processing steps. In addition, the adjusting device can therefore be easily displaced and secured in an operationally reliable fashion in the central recess in the pole core without involving expenditure on complicated devices or the use of tools.
According to one preferred embodiment of the disclosure, the solenoid valve comprises a pressure element which makes contact with the return element. The pressure element permits the return element to be securely supported. In addition, the pressure element permits pre-mounting of an armature assembly comprising the armature, the valve member, the return element and the pressure element.
Furthermore, the adjusting device preferably makes contact with the pressure element. This makes it possible largely to avoid disruptive influences by the magnetic field by appropriately adjusting the force of the return element or adjusting the working gap by means of a suitable thickness of the spring element.
In a further advantageous embodiment of the disclosure, a form fit is provided between the adjusting device and the armature. This ensures that the adjusting device is secured in an operationally reliable and simple fashion with expenditure on devices and tools which is minimized in terms of time and costs.
According to one preferred embodiment of the disclosure, that end side of the pole core which faces the armature has a first undercut. In a further advantageous embodiment of the disclosure, that end side of the armature which faces the pole core has a second undercut. Free spaces for the deformation of the spring element are made available by the undercuts in a cost-effective way. Furthermore, the volume of the working gap is only slightly increased as a result of this, therefore significantly reducing disruption of the magnetic circuit of the solenoid valve. The undercuts are preferably formed with a tapering shape.



BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary embodiments of the disclosure are described in detail below with reference to the accompanying drawings, in which:
FIG. 1 is a schematic sectional illustration of a solenoid valve for controlling a fluid according to a first exemplary embodiment of the disclosure,
FIG. 2 is an enlarged sectional illustration of part of the solenoid valve in FIGS. 1, and
FIG. 3 is a sectional illustration of part of the solenoid valve according to a second exemplary embodiment of the disclosure.



DETAILED DESCRIPTION
A solenoid valve for controlling a fluid according to a first preferred embodiment of the disclosure will be described in detail below with reference to FIGS. 1 and 2.
FIG. 1 shows a schematic sectional illustration of a solenoid valve 1 for controlling a fluid according to a first exemplary embodiment of the disclosure. The solenoid valve 1 comprises a housing 40, in the interior of which an armature 2, a valve member 3 and a valve body 4 which is connected to the housing 40 are arranged coaxially with respect to a central axis X. An armature assembly comprises the armature 2, the valve member 3, a return element 7 and a pressure element 50 which bears against an adjusting device 12, wherein a working gap 51 is formed between the armature 2 and the pole core 41. The pole core 41 which is surrounded by a coil 42 is fastened to the housing 40 by means of a weld seam 43. When the solenoid valve 1 is actuated, the valve member 3 is moved in the direction of the central axis X toward the pole core 41, and when switching off occurs it is returned again to the home position by the return element 7.
As is also apparent from FIG. 1, a filter 45 is arranged on the outside of the valve body 4. A fluid, which is directed through the filter 45, flows through an inflow duct 46 formed perpendicularly with respect to the central axis X in the valve body 4, said fluid flowing in the direction of an arrow P and into a through-bore 49 formed coaxially with respect to the central axis X. In the valve body 4, a plurality of outflow ducts are formed parallel to the through-bore 49 and arranged coaxially in the circumferential direction, FIG. 1 showing only one of said coaxial ducts, which is characterized by the reference symbol 47. In addition, a bypass duct 18 for equalizing the pressure between the outflow duct 47 in the valve body 4 and the armature 2 in the housing 40 is formed in the valve body 4. A ball 48 closes off an end of the through-bore 49 which faces away from the valve element 3. The end of the through-bore 49 which faces the valve member 3 forms a through-opening 5 in the valve body 4 and has a valve seat 6. One end of part 10 of the valve element 3 bears against the valve seat 6 and, in the de-energized operating state of the solenoid valve 1, said end closes off the through-opening 5 and, when the solenoid valve 1 is actuated, said end lifts off from the valve seat 6 and opens said through-opening. The part 10 of the valve member 3 is guided in a movable fashion through an opening 9 in a baffle device 8, wherein the baffle device 8 is secured in the valve body 4. An annular gap 23, with a relatively large gap width for unimpeded movement of the valve member 3, is provided between the baffle device 8 and the part 10. The baffle device 8 causes the fluid flowing in through the through-opening 5 to be deflected by 180° in the direction of the outflow duct 47. The solenoid valve 1 according to the disclosure also comprises a spring element 11 which is embodied as a spring washer and is arranged in the working gap 51. The adjusting device 12 is in contact with the spring element 11 in order to adjust a spring force of the spring element 11.
As is apparent from FIG. 2, the spring element 11 has here a central opening 24 into which an end region 25 of the pressure element 50 is inserted. The spring element 11 bears with an internal circumference 11a on an end side 26, facing the armature 2, of the adjusting device 12 and with an external circumference 11b on the armature 2. In this first exemplary embodiment, the adjusting device 12 is embodied as a solid cylinder which is arranged in a central recess 22 in the pole core 41 and is secured to the pole core 41 by means of a form fit. By displacing and positioning the adjusting device 12 along an adjustment path S (characterized by a double arrow) in the recess 22 in the pole core 41, a position of the pressure element 50 and therefore the spring force of the spring element 11 are set during the mounting of the solenoid valve 1 before the insertion into the housing 40. As is also apparent from FIG. 2, that end side 17 of the pole core 41 which faces the armature 2 has a first undercut 19, and an end side 18, facing the pole core 41, of the armature 2 has a second undercut 20. The two undercuts 19, 20 are each of tapered design. The first and second undercuts 19, 20 make available a free space or deformation space for the spring element 11, the external circumference 11b of which spring element 11 is pressed or deformed coaxially with respect to the central axis X in the direction of the pole core 41 when the solenoid valve 1 is actuated. The specific bearing points of the spring element 11 result in a desired, slightly progressive spring characteristic curve which the effect of closing the valve. Together with the linear spring force characteristic curve of the return element 7, the characteristic curve of the spring element 11 which is switched in parallel results in an overall progressive spring characteristic curve which counteracts the progressive magnetic force profile and the continuous (proportional) adjustability of the solenoid valve is considerably improved.
FIG. 3 shows an enlarged sectional illustration of part of the solenoid valve 1 according to a second exemplary embodiment, wherein identical or functionally identical components are denoted by the same reference symbols as in the first exemplary embodiment. In this second exemplary embodiment, the adjusting device 12 is embodied as a tubular element which is arranged in the recess 22 in the pole core 41. The tubular adjusting device 12 is also secured here in a frictionally locking fashion to the armature 2 and is equally displaced along the adjustment path S and positioned during the mounting of the solenoid valve 1, and the spring force of the spring element 11 is therefore adjusted. In this second exemplary embodiment, the pressure element 50 is of elongated design and is made to extend through the adjusting device 12 and is supported on a base region 21 of the recess 22 in the pole core 41. The adjusting device 12 can alternatively also be embodied as a slotted sleeve. Dimensional deviations or fabrication tolerances of the spring element 11, for example in the thickness and evenness, as well as remaining burrs from the manufacturing process, can be largely compensated by the adjusting device 12. The use of spring elements 11 which are manufactured as mass-produced parts (for example through punching) is therefore possible. In addition, the installation of relatively thin spring elements 11 allows the working gap 51 to be reduced, thereby minimizing disrupting influences on the magnetic field.
The solenoid valve 1 according to the disclosure in the two described exemplary embodiments has the advantage that as a result of the displaceable and therefore adjustable adjusting device 12 it is possible to adjust the spring force of the spring element 11 in its interaction with the return element 7 and the pressure element 50 during the mounting. As a result of the adjustment of the spring force of the spring element 11 which has a closing effect it is therefore possible to counteract, during the actuation of the solenoid valve 1, the magnetic force which increases exponentially as the axial working gap 51 becomes smaller. As a result, the adjustability of the solenoid valve 1 is considerably improved and better functional precision is implemented at all operating points. Furthermore, a similar and largely corresponding functional characteristic or a small batch variation is achieved during the fabrication of the solenoid valves.

## Claims

1. A solenoid valve for controlling a fluid, comprising
an armature,
a pole core positioned in relation to the armature so that a working gap is provided between the armature and the pole core,
a valve member which is connected to the armature and is movable together with the armature,
a valve body with a through-opening on which a valve seat is formed, wherein the valve member is configured to open and close the through-opening on the valve seat,
a return element which is configured to apply a return force to the valve member in order to return the valve member to a closed state,
a spring element which is arranged in the working gap, and
an adjusting device which is in contact with the spring element in order to adjust a spring force of the spring element.

2. The solenoid valve according to claim 1, wherein the adjusting device is arranged on the pole core.

3. The solenoid valve according to claim 1, wherein the adjusting device is arranged in a central recess on the pole core.

4. The solenoid valve according to claim 1, wherein the spring element includes an annular washer spring having a central opening, and the adjusting device contacts an internal circumference of the spring element.

5. The solenoid valve according to claim 1, wherein the adjusting device is configured as one of a solid cylinder and a tubular element.

6. The solenoid valve according to claim 1, further comprising a pressure element positioned in contact with the return element.

7. A solenoid valve, for controlling a fluid, comprising:
an armature;
a pole core positioned in relation to the armature so that a working gap is provided between the armature and the pole core;
a valve member which is connected to the armature and is movable together with the armature;
a valve body with a through-opening on which a valve seat is formed, wherein the valve member is configured to open and close the through-opening on the valve seat;
a return element which is configured to apply a return force to the valve member in order to return the valve member to a closed state;
a spring element which is arranged in the working gap;
an adjusting device which is in contact with the spring element in order to adjust a spring force of the spring element; and
a pressure element positioned in contact with the return element,
wherein the adjusting device is positioned in contact with the pressure element.

8. The solenoid valve according to claim 1, wherein a form fit is provided between the adjusting device and the pole core.

9. The solenoid valve according to claim 1, wherein an end side of the pole core which faces the armature has a first undercut.

10. The solenoid valve according to claim 9, wherein an end side of the armature which faces the pole core has a second undercut.

11. The solenoid valve according to claim 10, wherein the first and second undercuts are tapered.

12. The solenoid valve according to claim 1, wherein the spring element is configured to contact the magnet armature to exert a spring force on the magnet armature.

13. The solenoid valve according to claim 1, wherein the return element is a helical spring.