Solenoid valve with pressed-in sealing element

Abstract

The invention relates to a solenoid valve for controlling a fuel injector with a housing, wherein the housing comprises a drain nozzle (1), an injector cap (2) and a magnetic sleeve (3) in which a magnetic core (4) with an embedded magnetic coil (5) is arranged, wherein at least one bore (6) is formed in the injector cap (2) in which a flat connector (7) is arranged, which surrounds a magnetic coil pin (8) for controlling the magnetic coil (5), wherein the magnetic coil pin (8) is fixed directly in the magnetic coil (5) and a sealing element (9) is arranged axially below the flat connector (7), which comes into contact with an axially below support ring (10). According to the invention, the sealing element (9) is pressed in between the flat connector (7) and the support ring (10) in order to increase the sealing effect of the sealing element (9) and to prevent axial movement of the sealing element (9) along the magnet coil pin (8), wherein the support ring (10) has at least one section (11) tapering towards an end face abutting the sealing element (9).

Description

[0001] The present invention relates to a solenoid valve for controlling a fuel injector with a housing, wherein the housing comprises a drain nozzle, an injector cap and a magnetic sleeve in which a magnetic core with an embedded magnetic coil is arranged, wherein at least one bore is formed in the injector cap in which a flat connector is arranged which surrounds a magnetic coil pin for controlling the magnetic coil, wherein the magnetic coil pin is fixed directly in the magnetic coil and a sealing element is arranged axially below the flat connector which bears against an axially below support ring. State of the art

[0002] Pressure-balanced solenoid common-rail injectors use solenoid assemblies to control the opening and closing of a valve. For sealing the electrical contact, established technology uses assemblies consisting of a support plate and an O-ring.

[0003] Furthermore, German patent application DE 196 50 865 A1 discloses a solenoid valve for controlling a fuel injector, comprising a housing consisting of a magnetic guide sleeve, a drain nozzle, and an injector cap. Inside the housing is a magnetic pot containing a solenoid coil. When energized, this coil generates a magnetic field that pulls a magnetic armature upwards against a spring force, thus actuating the solenoid valve. For electrical control of the solenoid valve, two additional contacts, connected to the contact pins of the solenoid coil, extend through the injector cap to the outside. The injector cap serves as electrical insulation for the contacts and as a protective cap against mechanical deformation of the contact pins.

[0004] Furthermore, patent specification EP 2 299 101 B1 discloses Fig. 3a A control unit, which is screwed to the injector body via a magnetic clamping nut. This unit comprises a magnetic core with an embedded magnetic coil, a magnetic sleeve, and a drain nozzle. The control unit is actuated via an electrical connection consisting of two flat connectors and two contact pins, each connected to the other via a plug connector. The magnetic coil in the magnetic core comprises two contact pins, each of which, together with a plug connector fixed to the end of the contact pins and the flat connectors, forms the electrical connection. The contact pins are guided in the mounting plate by a support plate. Sealing elements located on the mounting plate above the support plate seal the fuel-carrying area in the control unit, thus preventing fuel leakage along the electrical connection.

[0005] In Fig. Figure 4 of the aforementioned publication depicts a control unit for a solenoid valve, comprising a housing consisting of a magnetic sleeve and a drain nozzle. A magnetic core is arranged within the housing, supported against a shoulder of the magnetic sleeve, and the magnetic core accommodates a magnetic coil with contact pins. Each contact pin is encased in an insulating sleeve, the insulating sleeves being located in two bores formed in the drain nozzle. In the area of ​​the bores in the drain nozzle, between the access bores and the magnetic core, a sealing element is arranged on the outer surface of the insulating sleeve, on each sheath of the contact pins, which prevents fuel leakage along the path of the electrical connection. Alternatively, the insulating sleeve itself can be made of a hydraulically sealing material and pressed into the bore in such a way as to create a comparable sealing effect.

[0006] DE 102 51 225 A1 further discloses an injection valve with a piezo actuator whose contact pins are insulated by means of a sleeve, as does DE 10 2006 029 966 A1. DE 197 08 104 A1 and DE 102 40 880 A1 also disclose solenoid valves for fuel injectors whose contact pins are surrounded by a sealing ring.

[0007] The object of the present invention is therefore to improve a solenoid valve in such a way as to optimize the sealing of the electrical contacts. Furthermore, the wear on a sealing element and a solenoid coil pin is also to be reduced. To achieve this object, a solenoid valve with the features of claim 1 is proposed. Advantageous embodiments of the invention are specified in dependent claims 2-8. Disclosure of the invention

[0008] According to the invention, the sealing element is pressed between the flat connector and the support ring to increase the sealing effect of the sealing element and to prevent axial movement of the sealing element along the magnet coil pin, wherein the support ring has at least one section that tapers towards an end face abutting the sealing element. In other words, the sealing element is positioned between the flat connector and the support ring such that the sealing element rests securely against the flat connector and has no clearance from the flat connector.

[0009] Pressing the sealing element between the flat connector and the support ring reduces axial vibrations of the sealing element during solenoid valve operation. Furthermore, misalignment of the sealing element is reliably prevented, thus reducing wear on the solenoid pin and the sealing element, particularly axial scoring in the sealing element caused by misalignment and axial vibrations, through which the medium to be sealed can escape. In addition, due to isotropic pressure transmission of the sealing element, the contact pressure on the surfaces to be sealed is increased, thereby enhancing the sealing effect of the sealing element. The actual sealing effect is achieved exclusively through radial compression between the retaining plate and the solenoid pin. The purpose of the support ring according to the invention is to position the sealing element on the flat connector so that the sealing element cannot develop damaging misalignment due to pressure pulses during operation.

[0010] However, it should be noted that the pressed-in sealing element undergoes expansion, particularly at higher temperatures. To prevent damage to the sealing element due to excessive internal stresses, the support ring has at least one section that tapers towards an end face adjacent to the sealing element. In other words, a central section of the cross-sectional area has the greatest width because the cross-section decreases towards at least one end face due to the converging outer edges of the support ring. This tapering of the support ring creates sections in the area of ​​at least one end face that allow for expansion of the sealing element, thus ensuring the reduction of internal stresses.

[0011] Preferably, the at least one section of the support ring that tapers towards an end face has a flattened or rounded tip to prevent damage to the sealing element. The tip should advantageously be designed to provide a sufficiently large contact area with the sealing element. The smaller this contact area, the more room the sealing element has for expansion. Therefore, the size of the contact area depends, among other things, on the operating conditions and the expansion capacity of the sealing element. A rounded tip of the section of the support ring that tapers towards an end face also offers the advantage that there are no sharp corners that could cause damage when the sealing element expands.

[0012] Furthermore, it is preferred that one cross-sectional area of ​​the support ring is axially symmetrical and has two sections tapering towards the two end faces. Such a design of the support ring has the advantage of allowing it to be oriented independently of its position within the solenoid valve. This makes the assembly of the solenoid valve with respect to the support ring particularly simple.

[0013] According to a first preferred embodiment, the cross-sectional area of ​​the support ring has an octagonal shape. Advantageously, the octagonal shape is honeycomb-like. It is conceivable to round off the sharp corners of the support ring, at least the four sharp corners on the two end faces, in order to prevent damage to the sealing element.

[0014] According to a second preferred embodiment, the cross-sectional area of ​​the support ring has an oval shape. However, a circular cross-sectional area is also conceivable, preferably with a flattened region at the contact point with the sealing element. Due to the symmetry, the end face of the support ring facing away from the sealing element is also flattened. Furthermore, a flattening of the support ring on the outer circumferential surface and on the inner circumferential surface bearing against the magnet coil pin is also possible.

[0015] It is further proposed that the support ring be made of a polymer material. The choice of the specific polymer material depends on the operating conditions of the solenoid valve.

[0016] The invention includes the technical teaching that the support ring can be manufactured using injection molding. This proposes a manufacturing technique that ensures near-net-shape production of the support rings, thus eliminating the need for post-processing. Furthermore, this allows for the production of a high quantity of support rings.

[0017] According to a further improvement of the invention, it is proposed that the sealing element be an O-ring. O-rings are particularly suitable for this type of sealing problem.

[0018] Further measures improving the invention are described in more detail below, together with a description of preferred embodiments of the invention, with reference to figures. Examples of implementation

[0019] They show: Fig. 1 a partial longitudinal section through the solenoid valve according to the invention, comprising a support ring according to a first embodiment, and Fig. 2 a partial longitudinal section through the solenoid valve according to the invention, comprising a support ring according to a second embodiment.

[0020] After Fig. Figure 1 of the inventive solenoid valve for controlling a fuel injector comprises a housing including a drain nozzle (1), an injector cap (2), and a magnetic sleeve (3). A magnetic core (4) with an embedded magnetic coil (5) is arranged in the housing. Furthermore, a bore (6) for receiving a flat connector (7) is formed in the injector cap (2). The flat connector (7) surrounds a magnetic coil pin (8) for controlling the magnetic coil (5), the magnetic coil pin (8) being directly fixed in the magnetic coil (5). A sealing element (9) in the form of an O-ring is arranged axially below the flat connector (7), which bears against a support ring (10) located axially below it.

[0021] The sealing element (9) is pressed between the flat connector (7) and the support ring (10), thereby increasing the sealing effect of the sealing element (9) and preventing axial movement of the sealing element (9) along the magnet coil pin (8). The support ring (10) has a section (11a) that tapers towards an end face abutting the sealing element (9). Since the cross-sectional area of ​​the support ring (10) is axially symmetrical, an identical section 11b, also tapering towards the end face opposite the sealing element (9), is formed on the same end face. Both sections 11a and 11b of the support ring (10), tapering towards the end faces, have a flattened tip to prevent damage to the sealing element (9). The cross-sectional area of ​​the support ring (10) is octagonal.

[0022] In Fig.Figure 2 shows a further embodiment of the solenoid valve according to the invention. In particular, the support ring (10) in this embodiment has an oval cross-sectional area. The two sections 11a, 11b of the support ring (10), which taper towards the end faces, thus have a rounded tip, thereby preventing damage to the sealing element (9).

[0023] The exemplary embodiments are not to be understood as limiting the invention. Rather, numerous modifications are possible within the scope of the present disclosure, which, for example, can be deduced by a person skilled in the art with regard to solving the problem by combining or modifying individual features in conjunction with those described in the general description and embodiments as well as the claims and contained in the drawings, and which, through combinable features, lead to a new subject matter.

[0024] For example, it is possible to design the cross-sectional area of ​​the support ring 10 differently, provided that the possibility of expansion of the sealing element 9 and the increased sealing effect due to the pressing in of the sealing element 9 are maintained.

[0025] It should also be noted that "comprehensive" does not exclude any other elements and "a" or "an" does not exclude a plurality. Furthermore, it should be noted that features described with reference to one of the above embodiments can also be used in combination with other features of other embodiments described above. Reference numerals in the claims are not to be considered as a limitation.

Claims

[1] Solenoid valve for controlling a fuel injector with a housing, wherein the housing comprises a drain nozzle (1), an injector cap (2) and a magnetic sleeve (3) in which a magnetic core (4) with an embedded magnetic coil (5) is arranged, wherein at least one bore (6) is formed in the injector cap (2) in which a flat connector (7) is arranged, which encloses a magnetic coil pin (8) for controlling the magnetic coil (5), wherein the magnetic coil pin (8) is fixed directly in the magnetic coil (5) and a sealing element (9) is arranged axially below the flat connector (7), which bears against an axially below support ring (10), characterized by, that the sealing element (9) is pressed in between the flat connector (7) and the support ring (10) to increase the sealing effect of the sealing element (9) and to prevent axial movement of the sealing element (9) along the magnet coil pin (8), wherein the support ring (10) has at least one section (11) tapering towards an end face abutting the sealing element (9). [2] Solenoid valve according to claim 1, characterized by , that the at least one tapered section (11) of the support ring (10) has a flattened or rounded tip to avoid damage to the sealing element (9). [3] Solenoid valve according to claim 1, characterized by , that a cross-sectional area of ​​the support ring (10) is axially symmetric and has two sections (11a, 11b) that taper towards the two end faces. [4] Solenoid valve according to claim 3, characterized by, that the cross-sectional area of ​​the support ring (10) has an octagonal shape. [5] Solenoid valve according to claim 3, characterized by , that the cross-sectional area of ​​the support ring (10) has an oval shape. [6] Solenoid valve according to claim 1, characterized by , that the support ring (10) is made of a polymer material. [7] Solenoid valve according to claim 6, characterized by , that the support ring (10) can be manufactured using the injection molding process. [8] Solenoid valve according to claim 1, characterized by , that the sealing element (9) is an O-ring.

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