EP1960657A1

EP1960657A1 - Deformation-optimized armature guide for solenoid valves

Info

Publication number: EP1960657A1
Application number: EP06807272A
Authority: EP
Inventors: Andreas Rettich; Stefan Haug; Markus Rueckle; Stephan Amelang
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2005-12-07
Filing date: 2006-10-16
Publication date: 2008-08-27
Also published as: WO2007065752A1; US20080290196A1; CN101321945A; DE102005058302A1

Abstract

The invention relates to a fuel injector (1) having a solenoid valve (17) for actuating an armature assembly (10) which is configured in one piece or a plurality of pieces. A closing element (8) is actuated via this in order to relieve the pressure in a control space (4). The armature assembly (10) is guided in an armature guide (13) which is fastened in the injector body (2) by means of a valve clamping screw (21). In its fixing region (28) in the injector body (2), the armature guide (13) has at least one circumferential recess (33).

Description

description

title

Deformation-optimized armature guide for solenoid valves state of the art

DE 196 50 865 A1 describes a solenoid valve for controlling the fuel pressure in a control chamber of an injection valve, for example a common rail injection system. A stroke movement of a valve piston, with which an injection opening of the injection valve is opened or closed, is controlled via the fuel pressure in the control chamber. The solenoid valve comprises an electromagnet, a movable armature and a valve member which is moved with the armature and acted upon in the closing direction by a valve closing spring and which cooperates with the valve seat of the solenoid valve and thus controls the fuel outflow from the control chamber.

In known solenoid valves, the armature vibration and / or bouncing of the valve member that occurs during operation has a disadvantageous effect. By swinging the anchor plate hitting the valve seat takes an undefined position. In subsequent injections with the same activation, the solenoid valve opens differently and thus the start of injection and the injection quantity are scattered. According to DE 196 50 865 A1 and DE 197 08 104 A1, the armature of the solenoid valve is designed as a two-part armature assembly so as to reduce the moving mass of the armature and valve member unit and thus the kinetic energy causing the bouncing. The two-part armature comprises an armature bolt and an armature plate which is displaceably received on the armature bolt against the force of a return spring in the closing direction of the valve member under the action of its inertial mass and which is secured to the armature bolt by means of a locking washer and a locking sleeve surrounding it. The locking sleeve and locking washer are enclosed by the magnetic core, which results in an increased space requirement and which leads to a larger diameter in the magnetic core. Because of the larger diameter in the magnetic core, the magnetic flux is limited. The exact setting of the maximum path length, which is available to the anchor plate on the anchor bolt as a sliding path, has proven to be problematic. The maximum path length referred to as the stroke, which is made up of the anchor stroke and the overstroke, is generally measured with a standard disc. A classified shim is then inserted to set the desired stroke. The magnet group is then screwed to the injector body and then the stroke is measured in the screwed or clamped state. At most, tolerances in the micrometer range can be tolerated for the application in order to ensure reproduced injector behavior. To ensure that the narrow tolerance limits are actually adhered to, it is often necessary to dismantle the complete magnet group. The process may have to be repeated several times until acceptable tolerances are achieved, but this leads to high costs in production.

In order to avoid disassembly of the complete magnet group for exact setting of the stroke, a pre-assembly of an armature assembly is described in DE 102 32 718 A1. Here, the armature assembly comprises an armature bolt, an armature plate and a valve tensioning screw, designed as a fitting screw, with an armature bolt guide section. A pre-assembly that takes place outside the injector body allows a common setting of the tolerance of armature stroke and overstroke by means of a conical or cylindrical dowel pin that connects the armature plate with the armature bolt. It turns out to be disadvantageous that the number of elements to be assembled increases. To set a specified stroke, close tolerances must be observed for the dowel pin, anchor bolt and anchor plate to be connected, as well as the locating holes of the dowel pin. Simulation tests and measurements have shown that when the valve tension screw is screwed on and thus when the armature guide is fixed in the injector housing of a fuel injector, the armature guide is deformed. This deformation can cause the lubricating film to be pushed through during operation, so that the friction, in particular between the anchor bolt and the anchor guide, increases considerably. This friction in turn leads to a strongly scattering closing behavior of the anchor bolt, which in turn leads to different valve opening times.

DISCLOSURE OF THE INVENTION The object of the solution proposed according to the invention is to reduce the deformation of an armature guide when it is fixed within the injector body of a fuel injector. For this purpose, it is proposed according to the invention to make a recess in the component representing the armature guide, into which the elastic deformation of this component in the injector body is displaced when it is fixed by, for example, a valve clamping screw. Due to the displacement of the elastic deformation of the component constituting the anchor guide, its radial constriction is reduced, which hinders the movement of the anchor bolt of a one or more-part anchor assembly in the component representing the anchor guide. A radial constriction of the component constituting the armature guide increases the friction between the armature bolt of an armature assembly formed in one or more parts in such a way that the lifting movement of the armature bolt is impermissibly impeded.

The solution proposed according to the invention enables the radial constriction of the component representing the anchor guide to be reduced, so that the lubricating film formed between the anchor bolt and the inside of the component representing the anchor guide is also retained and material contact between the material of the anchor bolt and the Material of the component representing the anchor guide can be avoided.

drawing

The invention is described in more detail below with reference to the drawing.

1 shows a solenoid valve for a fuel injector with a multi-part design

Armature assembly,

Figure 2 in an enlarged, exaggerated representation, the deformation of the component representing the armature guide by a valve tension screw and

Figure 3 shows the anchor guide in an enlarged view.

Exemplary embodiment FIG. 1 shows a section through a solenoid valve of a fuel injector with an armature assembly which is constructed in several parts and has an armature bolt and an armature plate accommodated thereon. The fuel injector shown in Figure 1 comprises an injector body 2, in which an injection valve member 3 is movably guided. The injection valve member 3 is acted upon on one end face by the pressure prevailing in a control chamber 4. The control chamber 4 is filled via an inlet throttle 5. A closing element 8 serves to relieve the pressure in the control chamber 4 and closes a relief channel 6 with the outlet throttle 7 accommodated therein. The closing element 8, which is spherical in FIG. 1, is accommodated in a closing element guide body 9. The closing element guide body 9 is received on an anchor bolt 11 of a multi-part anchor 10. On the underside of the anchor bolt 11 there is a stop 12 configured in the form of a disk. The anchor bolt 11 is enclosed by an anchor guide 13. An anchor plate 15 is also received on the anchor bolt 11. The anchor plate 15 is enclosed by an anchor spring 18 which acts on the anchor plate 15 on its underside and also surrounds the anchor guide 13. In the upper part of the fuel injector 1 there is a solenoid valve 17 which has an electromagnet 16. The magnetic core of the electromagnet 16 has a bore C with a first diameter, into which the upper end of the armature bolt 11 projects. At the upper end of the anchor bolt 11 there is a locking washer B, which is enclosed by a locking sleeve A. Due to the selected arrangement, the dimension C, ie the diameter of the bore formed in the magnetic core, must be selected such that the locking sleeve A and the locking washer B are to be accommodated in it.

The armature assembly 10, which comprises the armature bolt 11 and the armature plate 15 guided thereon, is preloaded by means of a valve spring 20. The armature guide 13 is adjusted via the valve clamping screw 21 to an adjusting disk 22, which in turn is supported on a valve piece 23.

FIG. 2 shows the deformation of the armature guide of the shim as well as the end face of the valve piece in an exaggerated representation. It can be seen from the illustration in FIG. 2 that when the valve clamping screw 21 is tightened with a predetermined torque, it deforms a disk-shaped fixing area 28 at the lower end of the armature guide 13 in such a way that a deformation 25 occurs. Due to the deformation 25, a radial constriction 24 is established between the outer surface of the anchor bolt 11 and the inside of the anchor guide 13. In addition to the deformation of the valve clamping screw 21 and the deformation 25 of the fixing area 28 of the armature guide 13, the adjusting washer 22, on which the fixing area 28 of the armature guide 13 is supported, assumes a deformed state 26. Finally, the upper end face of the valve piece 23 is also shown as exaggerated in FIG Applying a predefined tightening torque to the valve clamping screw 21 as shown in FIG. 2, deformed. For reasons of symmetry, only one half of the armature guide 13 is shown, just as in FIG. 2 only one half of the valve clamping screw 21 and one half of the valve piece 23 are shown.

Figure 3 shows an anchor guide in an enlarged view.

3 shows that the anchor guide 13 has a first end face 30 on which the anchor plate 15 is supported as shown in FIG. 1. The anchor guide 13 further comprises the fixing area 28 shown in FIG. 2 in its deformed state, which is set by the valve clamping screw 21 on the adjusting disk 22, which is preferably a classified adjusting ring. The fixing area 28 of the anchor guide 13 according to FIG. 3 comprised an upper side 34 and a lower side 35. A circumferential recess 33 is made in the lower side 35, which e.g. can be groove-shaped and serves as relief. On the inner circumferential surface of the anchor guide 23 there is a guide surface 37 for the anchor bolt 11. The outer surface of the anchor bolt 11 and the inner circumferential surface of the anchor guide 13, i.e. the guide surface 37 for the anchor bolt 11 are made with a high surface quality. A lubricating film is formed between the anchor bolt 11 (not shown in FIG. 3) and the guide surface 34, which reduces the friction between the anchor bolt 11 and the guide surface 37 of the anchor guide 13 when the electromagnet 16 shown in FIG. 1 is actuated.

If the armature guide 13 shown in FIG. 3 is placed on the adjusting disk 22, which is also shown in FIG. 2, by acting on the valve clamping screw 21 as shown in FIG. 2, the fixing region 28 deforms due to the clamping force. The disc-shaped fixing area 28 can, however, be compressed due to the circumferential recess 33, formed in the underside 35 of the fixing region 28, so that the circumferential recess 33 does not hinder the elastic deformation of the fixing region 28 when it is acted upon by the torque of the valve clamping screw 21, but rather that displaced material during clamping. While the stretching of the upper side 34 of the fixing area 28 is not critical with regard to a radial constriction 24 of the anchor guide 13, the circumferential recess 33 on the underside 35 of the fixing area 28 favors a flow of the material of the anchor guide 13, so that material is displaced by compression can take place on the underside 35 of the fixing area 28 and the upsetting during the tightening of the fixing area 28 by tightening the valve clamping screw 21 does not lead to the radial constriction 24 shown in FIG. Thus, the between the anchor bolt 11 and the guide surface 37 of the anchor guide tion 13 forming lubricant film are preserved, which is represented in fuel injectors, for example, by the fuel. In the case of self-igniting internal combustion engines, the lubricant is therefore diesel oil. Accordingly, a material displacement occurring on the underside 35 of the fixing area 28 when the valve clamping screw 21 is tightened is intercepted by the circumferential recess 33. As a result, the guide surface 37 facing the anchor bolt 11 on the inside of the component which represents the anchor guide 13 is not or only insignificantly deformed. The material used for the material of the anchor bolt 11 and the anchor guide 13 surrounding it is predominantly lOOCrό. The valve clamping screw 21, which acts on the fixing area 28 of the armature guide 13 with a defined tightening torque, lies on the upper side 34 of the protruding surface in the fixing area 28 in FIG. 3. With the anchor guide 13 shown in FIG. 3, a radial constriction of 0.0212 μm can be achieved with a valve clamping screw force of approximately 18 kN. Instead of a circumferential recess 33, a plurality of circumferential recesses 33 running concentrically to one another can also be made on the underside 35 of the fixing region 28 of the anchor guide 13. The anchor guide 13 shown in FIG. 3 has a recess 33 on the underside 35 of the fixing region 28, which serves as a relief groove. Alternatively, the circumferential recess 33 can also be introduced on the top side 34 of the fixing region 28, but this is not shown in the drawing.

Claims

1. Fuel injector (1) with a solenoid valve (17), to which a single-part or multi-part armature assembly (10) is assigned, via which a closing element (8) for depressurizing a control chamber (4) is actuated and the armature assembly (10) in a

Anchor guide (13) is guided, which is fastened in the injector body (2) by means of a valve clamping screw (21), characterized in that the anchor guide (13) has at least one circumferential recess (33) in its fixing area (28) in the injector body (2) .

2. Fuel injector (1) according to claim 1, characterized in that the fixing area (28) is disc-shaped and either on its top (34) or on its bottom (35) comprises at least one circumferential recess (33).

3. Fuel injector (1) according to claim 1, characterized in that the at least one circumferential recess (33) is designed as a relief groove.

4. Fuel injector (1) according to claim 1, characterized in that the at least one circumferential recess (33) with respect to an outer diameter d _{a of} the fixing area (28) and an inner diameter U _{1 of} the armature guide (13) extends in an intermediate diameter range .

5. Fuel injector (1) according to claim 4, characterized in that the at least one circumferential recess (33) runs on a diameter - '-.

6. Fuel injector (1) according to claim 1, characterized in that the armature guide (13) has a guide surface (37) which ends in a chamfer (32) in the region of a second end face (31).

7. Fuel injector (1) according to claim 1, characterized in that the armature guide (13) in the state clamped by the valve clamping screw (21) has a radial constriction (24) of less than 0.03 μm.

8. Fuel injector (1) according to claim 7, characterized in that the radial constriction (24) is 0.02 μm.

9. Fuel injector (1) according to claim 2, characterized in that the fixing area (28) is provided on its upper side (34) with a bearing surface.