DE10148592A1 - Fuel injector - Google Patents

Abstract

A fuel injection valve (1), in particular for injecting fuel directly into the combustion chamber of a mixture-compressing, spark-ignited internal combustion engine, comprises an armature (20) which interacts with a magnet coil (10) and one with the armature (20) via a sleeve (21 ) operatively connected valve needle (3), on which a valve closing body (4) is provided, which forms a sealing seat together with a valve seat surface (6). A preliminary stroke spring (22) is arranged between the sleeve (21) and the armature (20). A stop ring (15) serving as an anchor stop is arranged on the outflow side of the anchor (20). On an end face (33) of the stop ring (15) facing the armature (20) and / or on a corresponding counter surface (38) of the armature (20) and / or on an end face (32) of the sleeve (20) facing the armature (20) 21) and / or a corresponding counter surface (39) of the armature (20), at least one recess (31; 37) is formed, which reduces an effective stop surface of the end face (32; 33).

Description

State of the art

The invention is based on a fuel injector according to the genus of the main claim.

From DE 198 49 210 A1 is already a Fuel injection valve for fuel injection systems from Internal combustion engines known, which is a solenoid, a through the solenoid in one stroke direction against one Return spring loaded armature and one with a Valve closing body related valve needle having. The anchor is between one with the valve pin connected, the movement of the armature in the stroke direction limiting first stop and one with the valve needle connected, the movement of the anchor against the Second stop movable to limit the stroke direction. There is one between the second stop and the anchor Damping spring arranged in the form of a plate spring.

A disadvantage of that known from DE 198 49 210 A1 On the one hand, fuel injection valve is that the manufacturing and assembly effort by at least one additional component is increased. On the other hand, it can be done, for example insert the diaphragm spring at an angle or through the Manufacturing occurring manufacturing tolerances to offsets or to tilt the anchor during the operation of the Fuel injector come. The consequences are strong Scattering in the anchor free path or in the amount of Vorhubspalts. Signs of wear that are uncompensated remain, then lead to malfunctions in the operation of the Fuel injector.

Advantages of the invention

The fuel injector according to the invention with the has characteristic features of the main claim in contrast, the advantage that through a targeted Reduction of the face of a sleeve and one Stop ring in the area of the anchor influence on the signs of wear occurring on these end faces can be taken, in particular Signs of wear on other components of the Fuel injector can be compensated so that the stroke of the valve needle remains constant.

By the measures listed in the subclaims advantageous developments of the main claim specified fuel injector possible.

It is particularly advantageous that the components in simpler Way provided with radial or annular recesses can be, making the area of the end faces arbitrary is changeable.

The number, size and arrangement of the radial recesses is arbitrary.

The recesses are produced, for example, by Milling possible in a simple and inexpensive way.

The simple form and is particularly advantageous Production of the annular recesses, which for example by turning in the same operation the manufacture of the components is possible.

drawing

Embodiments of the invention are in the drawing shown in simplified form and in the following Description explained in more detail. Show it:

Fig. 1 shows a schematic section through an embodiment of the invention designed according to the fuel injection valve,

Fig. 2 shows a schematic section in the region II in Fig. 1 of the invention designed according to the fuel injection valve in a slightly varied structure,

Fig. 3A is a schematic representation of the designated in Fig. 2 with the sleeve 21 embodied according to the invention the fuel injection valve,

Fig. 3B is a schematic plan view of the embodiment shown in Fig. 3A sleeve,

FIG. 4A is a schematic representation of a first embodiment of the stop ring designated in Fig. 2 with 15 of the invention designed according to the fuel injection valve,

FIG. 4B is a schematic plan view of the stop ring shown in Fig. 4A,

FIG. 5A shows a schematic illustration of a second exemplary embodiment of the stop ring designated by 15 in FIG. 2 of the fuel injector designed according to the invention, and

Fig. 5B is a schematic plan view of the stop ring shown in Fig. 5A.

Description of the embodiments

Before preferred exemplary embodiments of a fuel injection valve 1 according to the invention are described in more detail with reference to FIGS. 2 to 5, the fuel injection valve 1 with respect to its essential components will first be briefly explained with reference to FIG .

The fuel injection valve 1 is in the form of a fuel injection valve for fuel injection systems of mixture-compressing, spark-ignition internal combustion engines. The fuel injection valve 1 is particularly suitable for injecting fuel directly into a combustion chamber (not shown) of an internal combustion engine.

The fuel injection valve 1 consists of a nozzle body 2 , in which a valve needle 3 is arranged. The valve needle 3 is operatively connected to a valve closing body 4 , which cooperates with a valve seat surface 6 arranged on a valve seat body 5 to form a sealing seat. In the exemplary embodiment, the fuel injection valve 1 is an inward opening fuel injection valve 1 , which has a spray opening 7 . The nozzle body 2 is sealed by a seal 8 against the outer pole 9 of a solenoid 10 . The magnet coil 10 is encapsulated in a coil housing 11 and wound on a coil carrier 12 which bears against an inner pole 13 of the magnet coil 10 . The inner pole 13 and the outer pole 9 are separated from one another by a gap 26 and are supported on a connecting component 29 . The magnet coil 10 is excited via a line 19 by an electrical current that can be supplied via an electrical plug contact 17 . The plug contact 17 is surrounded by a plastic sheath 18 , which can be molded onto the inner pole 13 .

The valve needle 3 is guided in a valve needle guide 14 , which is disc-shaped. A paired stop ring 15 is used for stroke adjustment and as a lower anchor stop. An anchor 20 is located on the other side of the stop ring 15 . This is non-positively connected to the valve needle 3 via a sleeve 21 . A restoring spring 23 is supported on the sleeve 21 , which in the present design of the fuel injector 1 is preloaded by a sleeve 24 . Between the armature 20 and the sleeve 21 , a pre-stroke spring 22 is arranged, which has a lower spring constant than the return spring 23 and, in conjunction with a pre-stroke gap 34, enables the armature 20 to be pre-accelerated via an armature free travel before the valve needle 3 is tightened.

Preferably, both the sleeve 21 and the stop ring 15 is a surface structure, which is designed for example in the form of different types of recesses 31, whereby the armature 20 facing the outlet-side end face 32 of the sleeve 21 and an armature 20 facing the inlet-side end face 33 of the stop ring 15 so are formable in its area that an error caused by the operation of the fuel injector 1, wear on the end faces 32 and 33 is controllable to wear to be compensated in other components of the fuel injection valve 1, and therefore do not result in changes in stroke of the valve needle. 3 Malfunctions during continuous operation, which are caused, for example, by an excessively large static and / or dynamic flow rate due to an excessively large stroke of the valve needle 3 , can thereby be avoided. The recesses 31 can alternatively or additionally also be realized on the counter surface 38 or the counter surface 39 of the armature 20 .

The measures according to the invention are shown in detail in FIGS. 2 to 5 and explained in more detail in the description below.

In the valve needle guide 14 , in the armature 20 and on the valve seat body 5 , fuel channels 30 a to 30 c run. The fuel is supplied via a central fuel supply 16 and filtered by a filter element 25 . The fuel injector 1 is sealed by a seal 28 against a fuel distribution line, not shown.

In the idle state of the fuel injection valve 1 , the armature 20 is acted upon by the return spring 23 against the stroke direction via the sleeve 21 on the valve needle 3 in such a way that the valve closing body 4 on the valve seat 6 is held in sealing contact. The armature 20 lies on the stop ring 15 . When the magnet coil 10 is excited, it builds up a magnetic field which first moves the armature 20 against the spring force of the preliminary stroke spring 22 and then against the force of the return spring 23 in the stroke direction. The stroke of the armature 20 is divided into a preliminary stroke, which serves to close a preliminary stroke gap 34 , and an opening stroke, which is predetermined by a working gap 27 which is in the rest position between the inner pole 13 and the armature 20 . After passing through the forward stroke, the armature 20 takes the sleeve 21 , which is welded to the valve needle 3 , and thus also the valve needle 3 in the stroke direction. The valve closing body 4 , which is operatively connected to the valve needle 3 , lifts off the valve seat surface 6 , as a result of which the fuel is sprayed off.

If the coil current is switched off, the armature 20 drops from the inner pole 13 after the magnetic field has been sufficiently reduced by the pressure of the return spring 23 on the sleeve 21 , as a result of which the valve needle 3 moves counter to the stroke direction. As a result, the valve closing body 4 rests on the valve seat surface 6 and the fuel injection valve 1 is closed. The armature 20 is placed on the stop ring 15 .

FIG. 2 shows an excerpted sectional view of the section designated II in FIG. 1 from the fuel injection valve 1 designed according to the invention. Matching components are provided with matching reference numerals in all figures.

As already mentioned with reference to FIG. 1, the lower armature stop is formed by the stop ring 15 inserted into a recess 35 in the fuel injection valve 1 . The stop ring 15 has recesses 31 which, in the present exemplary embodiment, are introduced into the stop ring 15 in the radial direction and thereby form a crenellated surface structure. The area of the end face 33 of the stop ring 15 facing the armature 20 is thereby reduced compared to a full-surface stop ring 15 . Signs of wear on the end face 33 , which are induced by the armature 20 striking the stop ring 15 when the fuel injector 1 closes, reduce the stroke.

Likewise, the sleeve 21 , which is shown in FIG. 2 for the sake of clarity without the pre-lifting spring 22 , has radially extending recesses 31 on its end face 32 facing the armature 20 , which also form a crenellated surface structure. This also reduces the area of the end face 32 which can come into contact with the armature 20 . The signs of wear that occur when the fuel injector 1 is opened, when the armature 20 strikes the sleeve 21 after the forward stroke, also have a stroke-reducing effect.

The signs of wear of both components therefore work in the same direction, namely reducing the stroke and thus reducing the switching time. However, since signs of wear also occur on other components of fuel injector 1 , in particular in the sealing seat and on inner pole 13 , which both increase the stroke, they can compensate for one another.

The changes in stroke are compensated in particular for the fact that signs of wear, which occur in the sealing seat and at the upper armature stop at the inner pole 13 and inadmissibly increase the stroke of the valve needle 3 , by the controllable signs of wear at the lower armature stop on the stop ring 15 and on the sleeve 21 after the preliminary stroke has been completed be weighed, since these reduce the stroke of the valve needle 3 . By specifically targeting the surface design of the end faces 32 and 33 to compensate for these signs of wear, the entirety of the signs of wear no longer have a stroke-changing effect.

It is considerably easier to modify the components of the stop ring 15 and the sleeve 21 so that a fixed wear effect can occur than to compensate for the wear in the sealing seat due to complicated reshaping of the valve seat body 5 or the valve seat surface 6 . The wear resistance of the armature stop surface on the inner pole 13 , against which the armature 20 strikes after passing through the opening stroke, is also difficult to influence due to hydraulic conditions.

FIG. 3A shows a schematic illustration of the sleeve, designated 21 in FIG. 2, of the fuel injector designed according to the invention.

As already explained with reference to FIG. 2, the sleeve 21 has recesses 31 on its downstream side 32 facing the armature 20 . In the present exemplary embodiment, four recesses 31 are provided. The holding function of the sleeve 21 for the preliminary stroke spring 22 is not impaired by the recesses 31 , since this is clamped between the armature 20 and a collar 36 .

FIG. 3B shows a schematic top view of the sleeve 21 shown in FIG. 3A. The recesses 31 are made at equal angular intervals of approximately 90 ° in the end face 32 of the sleeve 21 , which creates a crenellated surface structure. The surface of the end face 32 is reduced by the amount of the area lowered in the recesses 31 . For the targeted control of the signs of wear, more or fewer recesses 31 with a larger or smaller angular extent can be provided at larger or smaller distances from one another.

FIG. 4A shows a schematic illustration of a first exemplary embodiment of the stop ring designated by 15 in FIG. 2 of the fuel injection valve 1 designed according to the invention.

Like the sleeve 21 already described, the first exemplary embodiment of a stop ring 15 according to the invention shown in FIG. 4A has a plurality of recesses 31 which reduce the area of the stop ring 15 . In the first exemplary embodiment, twelve recesses 31 are provided which, as can be seen from the schematic top view according to FIG. 4B on the stop ring 15 shown in FIG. 4A, are likewise arranged at constant angular intervals of approximately 30 °.

For the targeted control of the signs of wear, more or fewer recesses 31 with a larger or smaller angular extent can also be provided at larger or smaller distances from one another.

Fig. 5A and 5B show a schematic diagram and a schematic plan view of a second embodiment of the stop ring designated in Fig. 2 with 15 of the invention designed according to the fuel injection valve 1.

In contrast to the first exemplary embodiment shown in FIGS. 4A and 4B, the stop ring 15 here does not have a plurality of radial recesses 31 but an annular recess 37 which is formed on a radially outer region of the stop ring 15 . The mode of operation of the annular recess 37 is equivalent to that of the radial recesses 31 , since the area of the end face 33 facing the armature 20 is also reduced.

To influence the signs of wear, the annular recess 37 can be made wider or narrower in the radial direction.

The second embodiment stands out in particular due to its simple manufacture, for example by turning or milling.

The annular recess 37 can also be transferred to the sleeve 21 , where it can also be attached in a radially outer region.

The invention is not restricted to the exemplary embodiments shown and can also be used for other forms of anchors 20 , for example for submersible and flat anchors, as well as any construction of fuel injection valves 1 .

Claims (9)

1. Fuel injection valve ( 1 ), in particular for injecting fuel directly into the combustion chamber of a mixture-compressing, spark-ignited internal combustion engine, with an armature ( 20 ) which interacts with a solenoid coil ( 10 ) and one with the armature ( 20 ) via a sleeve ( 21 ) operatively connected valve needle ( 3 ) on which a valve closing body ( 4 ) is provided, which forms a sealing seat together with a valve seat surface ( 6 ), and a pre-lift spring ( 22 ) arranged between the sleeve ( 21 ) and the armature ( 20 ) ) and a stop ring ( 15 ) serving as an anchor stop, which is arranged on the downstream side of the anchor ( 20 ), characterized in that on an end face ( 33 ) of the stop ring ( 15 ) facing the anchor ( 20 ) and / or on a corresponding counter surface ( 38 ) of the armature ( 20 ) and / or on an end face ( 32 ) of the sleeve ( 21 ) facing the armature ( 20 ) and / or a corresponding counter surface ( 39 ) of the armature s ( 20 ) at least one recess ( 31 ; 37 ) is formed, which reduces an effective stop surface of the end faces ( 32 ; 33 ). 2. Fuel injection valve according to claim 1, characterized in that a plurality of recesses ( 31 ) are provided. 3. Fuel injection valve according to claim 2, characterized in that the recesses ( 31 ) are introduced in the radial direction in the end faces ( 32 ; 33 ). 4. Fuel injection valve according to one of claims 1 to 3, characterized in that the radial recesses ( 31 ) are introduced at equal angular intervals in the end faces ( 32 ; 33 ). 5. Fuel injection valve according to one of claims 1 to 4, characterized in that the radial recesses ( 31 ) take up the same angular ranges. 6. Fuel injection valve according to claim 1, characterized in that the recesses ( 37 ) are annular. 7. Fuel injection valve according to claim 6, characterized in that the annular recesses ( 37 ) are formed in a radially outer region of the end faces ( 32 ; 33 ). 8. Fuel injection valve according to claim 6 or 7, characterized in that the annular recesses ( 37 ) are made by turning. 9. Fuel injection valve according to one of claims 1 to 8, characterized in that the recesses ( 31 ; 37 ) are made by milling.